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Choosing reliable and choice shrubs

September 5, 2023 • Leave a Comment

These handy lists will help you select excellent shrubs and place them in the right spots

Shrubs play a major role in landscaping, as we create a hedge here and cover the ground there, there, develop a backdrop in one spot and a pivotal year-round focal point in another. As I design, each shrubby player begins as a set of desirable characteristics, sans name. My rough sketch might have a note like this next to a prominent circle: “Eight feet tall, rounded in outline, winter interest, and color in one or more seasons.” Then, auditions begin and I select possibilities, working from a list of about 200 choice shrubs I’ve come to know how to use. Once the field is narrowed to just 2 or 3 candidates for each role, I consider how those in that smaller group will play as a team and perform in the given environment. In the end I have a line-up in which every plant can shine.

I expect that all my life I will keep trying shrubs I haven’t grown before, so this list will change in time. Certainly there are some that will take the places of my current favorites.

For instance, there’s cinnamon clethra (Clethra acuminata), a tree-like shrub I want to plant and watch in various sites to see for myself if its bark is always so gorgeous as I’ve seen at botanical gardens. Its flowers aren’t nearly so fragrant as those of its little cousin now on my list, but a winter’s worth of pretty bark could trump summer scent.

There are dozens of St. John’s worts (Hypericum) to try too. If it turns out that golden St. John’s wort (H. frondosum) keeps its blue-green character and bigger, brighter yellow flowers even once it’s old, in all kinds of sites, it may replace Kalm’s St. John’s wort on my drawing board.

And there are so many natives still being selected and developed. I hope to try some selections of leadplant (Amorpha canescens), with gray foliage and violet flowers in summer. My bet is that it will be a better groundcover for the Midwest than creeping cotoneaster.

Oh, for a dozen lifetimes so I could try and report on them all—bush whacky!

Big, multi-season beauties

Chinese spicebush (Lindera angustifolia)
10- to 12-foot, upright shrub with fragrant foliage, twigs, and seeds. It opens small yellow flowers in abundance in April. The foliage glows a pretty orange in fall but then fades to parchment and hangs on over winter in zone 5. It can be evergreen in milder zones. So the plant is a natural as a four-season screen. Part shade or full sun.

Choice shrub: Chinese spicebush (Lindera angustifolia) — **Chinese spicebush (*Lindera angustifolia*)**

Chokeberry (Aronia arbutifolia)
6- to 10-foot, upright shrub. Can be a specimen, but over time can sucker to form large colonies, so it’s good for naturalizing. Small white flowers in May. Great fall color, purple to maroon. Showy red fruit forms in late summer and remains into winter or until birds pluck it all. A workhorse, adaptable to various soils and moisture conditions. Sun or half shade.

Koreanspice viburnum (Viburnum carlesii)
Rounded, dense shrub, 8 to 10 feet by 8 to 10 feet, unless you happen upon the half-size variety ‘Compacta.’ White flowers in showy round clusters in late April or early May fill a yard with outstanding spicy scent. Might develop shining red fruit if there are viburnums nearby that are closely related. Fall color sometimes a pleasing maroon.

Choice shrub: Laceleaf red elder (Sambucus racemosa varieties) — **Laceleaf red elder (*Sambucus racemosa* varieties)**

Laceleaf red elder (Sambucus racemosa varieties)
Upright woodland native with white flowers in flat-topped clusters in early summer, followed by red berries. 10 feet tall. Look for the half-size dwarf and gold laceleaf forms.

Leatherleaf viburnum (Viburnum x rhytidophylloides)
Upright, 12 to 15 feet. Tree-like, especially in shade where foliage is most dense at the top of the plant. White lace-cap flowers in May, berries in June and July that age from red to black. Coarse foliage that’s dusky purple in fall. Fast to grow, very tolerant of shade and semi-evergreen to evergreen, so it’s very useful as a screen.

Choice shrub: Panicle hydrangea (Hydrangea paniculata) — **Panicle hydrangea (*Hydrangea paniculata*)**

Panicle hydrangea (Hydrangea paniculata)
Large white flowers in conical clusters in July or August age to pink and persist through winter. Many varieties. 8 to 10 feet tall and twice as wide, but about half that if cut back to the ground every year or two. Blooms on new wood so is reliably showy even where winters are harsh or it’s pruned hard. Sun to part shade. Very tolerant of shade but develops fewer blooms.

Onondaga viburnum (Viburnum sargentii ‘Onondaga’)
8-foot upright shrub, like a small tree. Foliage emerges maroon, changes to glossy green with a rose tinge for summer and glows red to purple in fall. Flowers in lacy, flat-topped clusters in May are deep pink in bud, white in full bloom, then salmon with age. Full sun to part shade.

Seven-son flower (Heptacodium miconioides)
Upright shrub, tree-like, fast growing to 15 to 20 feet. Showy, extremely fragrant white flowers in September become attractive pink seed pods in October. Peeling bark is ivory, white, and parchment—very attractive in winter. Full sun to part shade.

Spring witch hazel (Hamamelis mollis and H. vernalis hybrids)
10 feet tall and wide, with dramatic horizontal branching and most foliage held high. Use it like a small, broad-topped tree in almost any light situation. Best in the half shade. In full sun the plant’s lines are less dramatic and foliage may scorch in summer. In the shade flowering will be less heavy. Yellow to orange or red, sweetly fragrant flowers in February and March. Butter yellow, apricot, or glowing orange fall color. Many good varieties. One special favorite is ‘Jelena,’ with red-orange flowers and orange fall color.

Choice shrub: Variegated redtwig dogwood (Cornus alba 'Elegantissima') — **Variegated redtwig dogwood (*Cornus alba* ‘Elegantissima’)**

Variegated redtwig dogwood (Cornus alba ‘Elegantissima’)
White-edged leaves, red twigs in winter, 8 feet tall and 12 feet wide, but half that size if old wood is cut out each spring to stimulate more bright colored new wood, or the whole plant is cut to the ground every couple of years in spring. Flowers white on year-old and older wood, then bears blue berries in midsummer that are eaten by birds. I love this redtwig best but there are many other great varieties, some with gold-edged leaves or twigs more orange, scarlet, or maroon. Part shade. With plenty of moisture, it grows well in full sun.

Big, with one main show

Bottlebrush buckeye (Aesculus parvifolia)
Big, bold foliage on a suckering shrub that holds up hundreds of ivory candles each June or early July. Fall color is yellow at best and in winter the shrub is nearly see-through. I love it because the hummingbirds love it—and for its fresh, showy bloom after all the spring shrubs have finished. I expect it to be 8 to 10 feet tall and wide (and accept that we’ll have to remove suckers beyond its allotted space) but know it can be twice that if it really likes the site. Sun or part shade.

Choice shrub: Bottlebrush buckeye (Aesculus parvifolia) — **Bottlebrush buckeye (*Aesculus parvifolia*)**

Fragrant honeysuckle (Lonicera fragrantissima)
6 to 10 feet tall and round. A wallflower in terms of leaf and form—even a bit shabby in winter for its thin, arching, and somewhat disordered branches. Still, unmatched for very early spring fragrance. Give it a spot in the background or hedge. Full sun to part shade.

Quince (Chaenomeles speciosa)
Densely branched, glossy-leaf shrub makes an outstanding, unmatchable show of scarlet, rose, or salmon in May followed closely by red-purple of the emerging foliage. 8 by 8 feet, dense, deep green, suckering and thorny, it’s an impenetrable hedge or stand-alone thicket. I wish more properties had room and more gardeners the tolerance to grow it. Orioles and hummingbirds love its flowers and small birds its shelter. Full sun; don’t be taken in by the claim that it tolerates shade, which it does only at the cost of its primary asset: the bloom. Newer thornless varieties are available.

Choice shrub: Snowmound spirea (Spiraea x vanhouttei) — **Snowmound spirea (*Spiraea* x vanhouttei)**

Snowmound spirea (Spiraea x vanhouttei)
White lacy flowers in dense clusters along the arching stems in May and June. A shrubby mound so densely twiggy it’s a screen even when leafless in winter. Blue-green foliage is sometimes a nice peach in fall. Larger but more graceful than Japanese snowmound. Birds love its shelter so much it never needs fertilization for all the droppings that fall there. Fast growing to 8 feet tall and wide. Full sun but very tolerant of shade.

Choice shrub: Summersweet (Clethra alnifolia) — **Summersweet (*Clethra alnifolia*)**

Summersweet (Clethra alnifolia)
5 to 8 feet tall and not quite as wide. White or pink-tinged flowers on finger-length wands in July. Some varieties are shorter, later to bloom or have more pink in the flower bud. The best feature of the plant is the spicy sweet scent. Foliage is clean green in summer and sometimes copper in fall. Attractive to hummingbirds. I cut summersweet back to the ground every 2 or 3 years to keep it small; since it blooms on new wood that never stops the flower show.

Ural false spirea (Sorbaria sorbifolia)
Ferny-leafed shrub covered in feathery white plumes in July which repeat in August. Attractive to butterflies. 10 feet tall and as wide as you allow it to sucker. Blooms on new wood so can be cut to the ground each spring, in which case it is 5 to 6 feet tall. Variety ‘Sem’ is half size, even when left un-cut. Nice coppery color as the foliage emerges early in spring, and sometimes peachy in fall.

Satisfactorily small and multi-talented

Barberry (Berberis thunbergii)
Dense, reliable shrub for full sun. Greatest return from varieties with red, gold, and variegated foliage. 6 feet tall and wide. Density and nasty thorns make it an excellent mounded, no-prune hedge. If you must have a rectangular hedge, plant an upright form such as ‘Sunjoy Gold Pillar’ and skip the pruning with its painful clean-up. Dwarf, mounded 18-inch by 36-inch forms are delightful (‘Gold Nugget,’ ‘Crimson Pygmy’). Insignificant flowers, may have red berries in winter.

Choice shrub: Beautyberry (Callicarpa dichotoma) — **Beautyberry (*Callicarpa dichotoma*)**

Beautyberry (Callicarpa dichotoma)
A wide mound of nearly horizontal stems, 3 to 4 feet tall. Tiny flowers in July become clusters of purple fruit lining the branches. A showstopper in October when the leaves go golden and the fruit is the most purple. Full sun or part shade. Blooms on new wood and can be treated as a perennial, cut to the ground each year.

Blue mist spirea (Caryopteris x clandonensis)
5-foot round mound of gray stems with gray-green foliage and lacy blue flowers in August. All parts of the plant are sweetly fragrant. Blooms on new wood so can be cut to the ground each spring (and branches may die back in zone 5 anyway). Cutback and dieback shrubs usually reach only 3 to 4 feet. Gold-leaf variety ‘Worcester Gold’ and related C. divaricata ‘Snow Fairy’ with white-edged leaves show off their flowers to even greater advantage. Full sun. Don’t believe claims of shade tolerance—only in sun does it develop good bloom and scent.

Creeping cotoneaster (Cotoneaster adpressus)
12- to 18-inch horizontally branching shrub with pink or white flowers in June, then red berries that can be very showy in fall and persist into winter before being eaten by birds. Great for covering ground since it spreads by rooting where branches make good contact with soil. Full sun.

Choice shrub: Dwarf spirea (Spiraea x bumalda) — **Dwarf spirea (*Spiraea* x bumalda)**

Dwarf spirea (Spiraea x bumalda)
2 to 3 feet tall and wide. Branches honey brown and so dense that the plant is a significant presence even when leafless in winter. Pink, rose, or white flowers in June and July will repeat in August if the shrub is sheared to deadhead it. Blooms on new wood and can be grown as a perennial, by cutting it to the ground each spring (the first bloom will be delayed into July). Some varieties have colorful foliage in summer (‘Gold Mound,’ ‘Lime Mound,’ etc.) and some have seasonally changing color (‘Gold Flame’ begins orange in spring, is gold in summer and orange once again in fall). Best in full sun but tolerant of part shade.

Kalm’s St. John’s wort (Hypericum kalmianum)
2- to 3-foot round, dense, with blue-green leaves. Makes a good foil for spring-blooming perennials and then picks up the garden with bright yellow, furry-centered flowers over many weeks beginning in July. Full sun.

Slender deutzia (Deutzia gracilis)
Dense, twiggy plant that manages to bloom almost as well in shade as sun. 4 to 6 feet tall and almost as wide, dwarf ‘Nikko’ is half that height and broader than tall. Gray twigs can be a pretty structure in winter in combination with evergreen perennials. White dangling flowers all along the branches in May.

Virginia sweetspire (Itea virginica)
Arching stems, 4 to 5 feet tall (half height in dwarf forms such as ‘Little Henry’). Part sun. Native along moist streambanks in sun and shade where it suckers to form groundcovering colonies. Blooms white in June but grow it where you will see its most valuable asset: the very late, glowing red-purple fall color.

Evergreens

Bird’s nest spruce (Picea abies ‘Nidiformis’)
Irregularly mounded, dense, and eventually 4 feet tall and twice as wide. It may develop a depression in top center. If it must be kept smaller than its potential, prune every year or two beginning as soon as it reaches maximum allowable size. Full sun to part shade.

Choice shrub: Bird’s nest spruce (Picea abies 'Nidiformis' — **Bird’s nest spruce (*Picea abies* ‘Nidiformis’)**

Blue star juniper (Juniperus squamata ‘Blue Star’)
Its blue foliage is bright in summer, steely in winter. Slow to grow and compact, might eventually be 2 feet tall and half again as wide. Has rather brittle branches so don’t plant it where feet may stray or snow might be stacked in winter. Full sun.

Dwarf white pine (Pinus strobus ‘Nana’)
Mounded or wide, irregularly spreading, light green plant with long, soft needles. Luminous in winter. May reach 6 feet tall and 10 feet wide but can be kept smaller if pruned every year or two beginning as soon as it reaches the desired height and width. Full sun to part shade, and amazingly tolerant of shade although much more open and slow growing there.

Goldthread falsecypress (Chamaecyparis pisifera ‘Filifera Aurea’)
Mound of feathery, gold-tipped foliage forms a broad pyramid 10 to 15 feet tall. Dwarf varieties include ‘Golden Mop,’ ‘Vintage Gold,’ and ‘Lemon Thread.’

Hinoki falsecypress (Chamaecyparis obtusa ‘Nana’)
Very dense, slow-growing dwarf with irregular fans and ridges, very dark green foliage and brighter green new growth. It has the look of a dark green, coral outcrop. 2 feet tall and half again as wide. Full sun to part shade.

Choice shrub: Sargent hemlock (Tsuga canadensis 'Sargentii') — **Sargent hemlock (*Tsuga canadensis* ‘Sargentii’)**

Sargent hemlock (Tsuga canadensis ‘Sargentii’)
The king of feathery evergreens, it makes a graceful mound 8 feet tall and 2 or 3 times as wide, or a small weeping tree. Part shade or sun.

Ward’s yew (Taxus x media ‘Wardii’)
Dark green, dense, wide-spreading beauty in sun or shade. Red “berries” in winter add interest. 4 to 8 feet tall and 10 feet wide or wider. Can be kept smaller, even sheared into geometric forms, but is best used if grown for or pruned for its graceful natural form with feathered edges. For hedges and sheared shapes, use the more regularly-shaped, upright ‘Hicks’ or rounded ‘Densiformis’ yews.

Article by Janet Macunovich and photos by Steven Nikkila, www.gardenatoz.com.

RELATED: See “Website Extra: Janet’s Guide to Shrubs” for additional useful lists for shrubs in this article, such as:

Shade
April/May/early June bloom
Bloom in late June or later
Fragrance
Fall color
Birds and butterflies
Winter interest
Screen or hedge
Colorful fruit
Colorful foliage in summer
Long lived without pruning
Hardiest

ELSEWHERE: A homeowner’s guide to nutrition and fertilization of landscape trees and shrubs

Springtime: Reassurgence in the garden

March 16, 2023 • Leave a Comment

Will I ever in my lifetime feel sure at spring? After decades of observation, I still find myself on pins and needles wondering about certain plants and events in the springtime. Shouldn’t this one be back up by now? Weren’t there more of that one last year—did I take some out or what happened? What I did last fall—has it helped or hurt?

One part of me wants to figure it out and stop this worrying and wondering. Another thrills at the suspense, grows on the nervous tension, and learns a bit each year. Here I’ll tell you about some of the recurring questions I’ve put to rest. If you are like me—in need of reassurance at this resurgent season—these things, at least, you can be sure of…

Assurance #1: The bees will be there—on time, every time

A garden’s bloom season may begin on a different calendar date each year, as winter wraps up early or late. Yet on the day the first flower opens in your garden, bees will be there to sip its nectar. I was awed by the bees’ appearance the first time I saw my earliest crocus (C. minimus) on its first day. Since then, having seen it happen many times, the awe has mellowed but never left me.

I am assured bees will find the first flower, or that aphids will appear on the first succulent spirea shoots, and locust plant bugs will emerge as their host plants break bud. Each insect species has honed its timing through thousands of generations, so that they dance to the same tune as the plants they depend upon.

In both plant and insect, internal meters begin to run at the freeze that ends one season, accumulating time toward the wake-up bell for the next. On each day that temperatures rise above 40, for however many hours they hover there, insect eggs and larvae move forward in their development and plant cells chip away at chemicals that built up during fall as insurance against any resumption of growth before a safe time. In a related heat-registry, overwintering adult insects reckon safe emergence time. We humans have observed and recorded this timing in total degrees and hours, and converted it to “degree days.” At agricultural university Extension offices where such information is vital, we start our own meters at fall’s end to mark these units of time and say, for example, “Ah ha, 220 degree days have accumulated. Usually that happens about May 7 but this year it’s early…at any rate, it’s now time to look for honey locust plant bugs appearing from their wintering state.”

It’s an exquisite timing, particular to every region and microclimate. Degree days stack up more quickly one block uphill from me in Jack’s yard, which sheds its cold air downslope to pool in mine. So his crocus may open sooner than mine, and so too will the bees wintering in niches in his yard.

Do the first crocuses call the bees? Do the first bees tease the earliest flowers into opening? No, they've simply both tuned their springtime wake-up alarms to the same degree day. — **Do the first crocuses call the bees? Do the first bees tease the earliest flowers into opening? No, they’ve simply both tuned their springtime wake-up alarms to the same degree day.**

Assurance #2: Bugs will get ahead of you

So is it any wonder that even when we promise a favorite plant we’ll watch out for it next year, its predators find its new growth before we do? Insects and animals that rely on a plant are out there 24/7, awaiting or directly linked to their particular prey. As weekend warriors, we can’t beat that.

We can stay even by keeping sight of two facts, however. One, for most plant eaters, emergence coincides with their own plant’s new growth. Two, baby bugs are easier to kill than older, tougher individuals. Someone who told you they controlled aphids on a viburnum by, “just dousing it with the rinse water after I washed dishes,” was not telling tales even though this tactic may have failed in your yard. Apply soap (over-the-counter insecticidal soap spray or water plus dish soap) when the viburnum is just budding out and the day-old skins of its aphids will dry and split. Spray it on week-old aphids and those hardened veterans may break out loofah sponges and begin a chorus of Singin’ in the Rain.

Don’t let this news get you down. Most plants can manage despite the chewing, sucking or scraping of their usual predators. If they look worn or tattered as a result but have lost less than 20 percent of their leaf surface, they’ve suffered only cosmetic damage. That can be ignored or grown over. Meanwhile, insects such as ladybugs and lacewings that eat other insects are also engaged in the degree day dance. They’ll emerge in time to capitalize on their own prey’s development.

I do very little in the way of bug killing, but quite a bit of bug encouraging. That is, I avoid insecticide and allow insect-sheltering debris to overwinter in order to have the continued presence of species we recognize as beneficial insects. Out in a garden where hundreds or even thousands of insect species live, there are 8 or 9 species of beneficials for every 1 or 2 plant-damaging insect species. These good guys do little or no damage to plants—for instance, they may dine on pollen—but many attack, parasitize or eat other insects.

In addition, I keep my plants healthy by putting them where they can grow most vigorously. Such plants are better equipped to produce the distasteful, deterrent and downright deadly chemicals their species have devised to thwart their predators.

Butterfly bush is a tough customer if it's grown where it belongs: in a sunny, sandy, well-drained and even dry spot. Cut it all you want whenever you want—you won't kill it. However, it's likely to be dying before you even cut it back in spring if it was planted where the drainage is poor. — Butterfly bush is a tough customer if it’s grown where it belongs: in a sunny, sandy, well-drained and even dry spot. Cut it all you want whenever you want—you won’t kill it. However, it’s likely to be dying before you even cut it back in spring if it was planted where the drainage is poor.

Assurance #3: Dead wood will fool the unsuspecting eye

As plants’ internally-concocted potions can dissuade insects and grazers, so can guilt turn people off from gardening. Don’t let it happen to you.

Lots of gardeners are more concerned about the damage they themselves have done, than what insects may do. “I pruned my butterfly bush at the wrong time and killed it,” is a common cry in this crowd. Let this spring mark the end of that lament, if it’s been voiced in your yard.

I can assure you that you cannot kill a butterfly bush (Buddleia davidii) by cutting it back in early spring, even to stubs an inch above ground, even removing all its wood that was beginning to bud out.

You can, however, cut a dead or dying butterfly bush and then blame yourself. If you’re in zone 5 or a warmer (higher number) zone and the bush was healthy last fall, it will be able to grow from one-inch stubs to 4 or 5 feet tall, and quickly, too.

If the bush is not healthy—particularly if it’s being grown in soil that’s overly moist or poorly drained—its crown and roots are susceptible to rot, which takes hold during winter and consumes the live tissue as spring ensues.

Another factor to consider is that some varieties of butterfly bush are not as hardy as others. In my experience, ‘Dark Knight’ is not to be trusted, whereas ‘Nanho Blue’ can probably handle even zone 4 cold if it’s given a well-drained, sandy site.

Roses prick gardeners with guilt too. I’ve watched for decades as roses are pruned at various times and stages of development, looking for proof that we “should not prune them too early.” In one instance, I checked in throughout the season on a public garden of several hundred roses pruned by a single horticulturist over a three-week period that included the “too early” days before forsythia bloom, and saw no ill effect.

As with butterfly bush, a rose may be dead or dying by pruning time. When we learn to look at the base of stems and crown of a shrub for signs of life such as moist, green cambium under the bark and white cores in branches, we will recognize deadwood when we cut it and be free of self reproach.

Assurance #4: Slow starters will start when you give up

Something else gardeners have a tough time accepting is the lateness of plants like hardy hibiscus (Hibiscus moscheutos), butterfly weed (Asclepias tuberosa), balloon flower (Platycodon), perennial ageratum (Conoclinium coelestinum), and groundcover plumbago (Ceratostigma plumbaginoides). These plants, big contributors to late summer bloom, all take their sweet time to emerge, avoiding the cold weather their new growth cannot tolerate by remaining dormant many degree days later than other plants.

So it’s a sure thing in spring that we will give up on one or another of these, give in to the urge to buy more plants, plant something “to replace” what we assume has failed, and soon after have two plants duking it out over the same space.

In fact, degree days may not be the only determinant of a slow starter’s emergence from winter rest. It could be that honest despair is a tonic to them, for they almost always pop up the day after a gardener has given up all hope, pouring his or her sense of loss down on that ground.

Ironically, this error can lead to a better garden. If you chance to buy the right type of plant and set it to grow where you believe the balloon flower or other supposed failure lies, you may produce a fine double-up. That is, if you plant an early riser that tends to nap through summer (early blooming bulbs, for instance), or a tap-rooted, spring-blooming species where a shallow-rooted character tallies (oriental poppy with hibiscus, for example), or a shallow-root spring bloomer with a deep-root sleepyhead (Sedum spurium with balloon flower), the two may go on happily for years together.

**Balloon flower is late to emerge, but worth the wait.**

Hardy hibiscus (H. moscheutos and its hybrids) often sleeps in until late May. It doesn't mind another plant's foliage occupying its air space in April and May, and its shallow roots can straddle deep-rooted spring bulbs such as daffodil and quamash (Camassia). — Hardy hibiscus (*H. moscheutos* and its hybrids) often sleeps in until late May. It doesn’t mind another plant’s foliage occupying its air space in April and May, and its shallow roots can straddle deep-rooted spring bulbs such as daffodil and quamash (*Camassia*).

Assurance #5: You’ll estimate wrong about the mulch you need

Another thing that goes on for years is ordering too much or too little mulch. We might get it right at first guess, then think, “But didn’t I use that much last year, even before adding the two new beds?” Or we might announce our intention to another member of the household who undermines our confidence by asking, “That much? Are you sure you need that much?”

Since too much or too little is more rule than exception, cover your bases. When you have the mulch delivered, don’t let it be dumped right in front of the garage door. Not unless you want to hear long-suffering sighs from family members for weeks, along the lines, “I wishI could put my car in the garage!“

Likewise, in a move to ward off an unwelcome impact on your days that can follow the spreading of too little mulch, always begin mulching in beds that you see every day. Leave the farthest beds for last. Then, if the mulch runs out before all bare soil is covered, the exposed ground will not glare at you every day for the week or two that inevitably separates mulching opportunities one and two.

When the mulch truck arrives, temper your optimism about how long it will take to spread. Don't dump the pile where it will block your garage door. — **When the mulch truck arrives, temper your optimism about how long it will take to spread. Don’t dump the pile where it will block your garage door.**

Assurance #6: The weather will conspire against you

One reason mulch follow-up rarely follows right on the heel of a mulch shortfall is the uncooperative nature of weather. If you chance to be gifted with a clear, cool day on the weekend or the day off work you chose for mulching, the next two picks you make will turn out to be filled with rain or sleet. Unless you garden in the Desert Southwest where weather reports are unnecessary because every day is sunny and dry, buy some rain gear. If you use it only once, you will still be glad. There’s a lot to be gained simply from telling the tale of working in the rain. Be sure to take a picture of you behind the wheelbarrow in the rain suit.

Another way that weather will do you in, but one in which you will probably be a co-conspirator, is in killing dahlias, elephant ears and caladiums. Although these roots you harvested last fall stored best through winter at 50 degrees, they won’t grow well now in soil that cool.

It’s a mistake to plant them outdoors before crabgrass season—about June 1 in my neighborhood—when the soil reaches 60 degrees. Once the tuber or corm you plant softens in the ground preparatory to sprouting, it’s susceptible to fungal attack in cold soil. Once the shoot begins to grow, the plant’s even more likely to be injured or infected. Such a plant may die, or limp into summer as a weakling.

If you’re itching to do something with those dahlia tubers or corms of elephant ear or caladium, divide any clumps now. Cut away any rotted sections. To be viable, a dahlia division must have a bit of last year’s stem included.

Then put just an inch of moist potting mix into a pot that’s eight inches deep or deeper, set the root in and add just enough potting mix to cover it. Put the pot in a warm place—no light needed—and check on it every few days. Your aim should be to keep it barely moist and to note when the shoot begins to grow. Once you see that, add more moist potting soil an inch at a time. Let the shoot show itself, cover it under an inch of potting mix, let it poke its tip up again and blanket it once more, until it reaches the top of the pot. Then put the pot into full sun. This process keeps you occupied for the last few weeks of unsettled weather and keeps the plant warm while it develops a stout shoot.

I hope you kept your dahlia, canna, caladiums and other clumps of tender perennials intact over winter. Divide them only when it's time to replant. Undivided clumps (dahlia, at left) store better with less chance of rot, just as a bruise-free potato or whole onion stores best. The canna (right) was cut before storage and has rotted sections. — I hope you kept your dahlia, canna, caladiums and other clumps of tender perennials intact over winter. Divide them only when it’s time to replant. Undivided clumps (dahlia, at left) store better with less chance of rot, just as a bruise-free potato or whole onion stores best. The canna (right) was cut before storage and has rotted sections.

When you divide, cut away any damaged section. This canna is more tolerant of cool soil than some tender perennial roots. Yet, why set it out early when the plant's best role is as a late summer filler? — When you divide, cut away any damaged section. This canna is more tolerant of cool soil than some tender perennial roots. Yet, why set it out early when the plant’s best role is as a late summer filler?

Elephant ears (Colocasia) don't grow well and may be stunted all summer if planted into cool soil. Delay outdoor planting of those that love warmth (caladium, dahlia, elephant ear, etc.) until the ground reaches 60 degrees, in June. — Elephant ears (*Colocasia*) don’t grow well and may be stunted all summer if planted into cool soil. Delay outdoor planting of those that love warmth (caladium, dahlia, elephant ear, etc.) until the ground reaches 60 degrees, in June.

Assurance #7: Blue and pink hydrangeas will disappoint you

Hydrangea failure is another weather-plus-gardener problem. Mophead hydrangeas (H. macrophylla) are not reliably bud hardy in continental zone 5. That means their roots and sometimes their stems survive winter but the buds often do not.

The problem there is that this species spends the latter half of summer preparing a bud that will be in shape to finish its growth and bloom the following July. If those buds, located at the tips of branches, die or are cut off, the plant begins over again but flowering-branch development is a lengthy process. It is very unlikely the shrub will be able to produce a blooming shoot between now and when fall ends its season.

Sometimes winter kills the buds. You can tell right now if that happened. Consider yourself fortunate and the plant placed well if the bud at the tip of the branch is alive. You’ll know that’s the case if it’s plump and moist. Such a bud probably just pushed its protective scales aside to begin to grow again. If it’s dried out, dead or gone, don’t expect any bloom. Your placement of the plant is to blame. You can try shifting it to a spot in your garden where a warmer, more humid microclimate prevails in winter.

You see, even if a blue or pink hydrangea’s buds made it through winter, they’re not out of the woods yet. Weather steps to the fore. Often, as surviving buds open in spring, they’re killed by late frost. If that happens, loop back two paragraphs and read “If those buds…” because the weather’s kicked the plant back to that start-over point.

How is this dismal news reassuring? It is because it can save a gardener months of suspense that end in disappointment. Look now and be reassured by the condition of the tip buds whether there’s any chance for bloom. If there is, keep a cloth sheet on hand and cover the shrub to trap some ground warmth on frosty spring nights. If you’re attentive it may yet keep its tips and bloom.

**The tip bud on a mophead hydrangea branch. It survived winter and is beginning to grow in spring, but has one last hurdle to clear: late spring frosts.**

Final reassurance: Revelation will come

Whether it’s an “ah-ha” based on something you read in a magazine, a connection you make because your nose knows something about soil temperature that cannot be expressed in words, or the sounds you hear from birds reach a place in your conscious where natural cues rank themselves in mysterious but meaningful groups, you will learn and have fun this spring. I’m sure of it.

Article by Janet Macunovich and photos by Steven Nikkila, www.gardenatoz.com.

Springtime bulb problems that you can solve in the fall

September 7, 2022 • Leave a Comment

Bulbs come up too early

If you want to avoid this problem, plant bulbs deep and don’t plant right next to a sunny south wall.

Bulb foliage may emerge during an extended winter thaw, or come up far enough during an early spring heat wave that we worry it will freeze when normal temperatures return. Relax. That plant may lose leaf tips to the cold, but it’s no big loss. A fully grown tulip or daffodil leaf may be 12 inches long. If it loses an inch at the tip—that part which sits above the zone protected by radiant heat from the soil—the remaining 11 inches is enough to fuel the plant’s growth and bloom.

A hard freeze can hurt if it comes after your bulbs’ flower buds emerge. If a hard freeze is forecast, you can cover bulbs with floating row cover cloth or newspaper to trap ground heat, or run sprinklers during the coldest hours to protect the plants via heat released by cooling water.

Some bulb species are prone to early growth (Dutch iris is an example). If you see a bulb act this way in your garden every year, don’t plant that species or variety anymore. Also, some places are more likely than others to heat up early. Beds along south-facing brick walls are at risk, as are sandy beds that slope south. Recognize these places and don’t grow bulbs there. Finally, some practices contribute to early rising. The most common is too-shallow planting.

Bloom one year, never again

Avoid this by planting your bulbs in full sun this fall. Where it’s already a problem, make site changes to let in more light or move the bulbs.

Most often, failure to bloom means a site is too shady. To flower, most spring bulbs need at least six hours of sun while their leaves are green. Given that, embryonic flower buds form in the bulb this summer to bloom next spring. New bulbs coming from a sunny bulb production field may have enough stored energy to bloom their first spring even in shade. From then on, it’s all downhill.

Shallow planting and summer moisture can also contribute. This is especially true of bulbs that have a tunic (a paper-like covering), such as tulips, daffodils, crocus, and gladiolas. Tunicate bulbs require hot, dry summers. When these bulbs are too cool or moist during summer, they may not form flowers.

The stems flop over before the plants bloom

These daffodils flopped when temperatures dropped suddenly one April day from the 70s to the teens. Within days, they were standing tall and blooming cheerily again. If, however, your bulbs flop even in good weather, the advice below is what you need.

In answer to this problem, select sunny spots for your bulbs, keep those beds well watered this fall and again next spring as the bulbs emerge, and use only slow-release fertilizers.

For example, daffodils might have stems that are not strong enough to support the weight of the flower. They either lean over from the base or bend right in the middle of the stem. On the double-flowered varieties, the weight of the bloom may cause the stem to break.

Weak stems are often the result of planting where there is too much shade. For example, daffodils need at least eight hours of sunlight to perform well. When the area is too shady, they often stretch to reach the sun, causing their stems to elongate and become weak.

As far as nutrition is concerned, “balanced” fertilizer is another possible culprit. Daffodils need a slow-release nitrogen in smaller quantities. Too much nitrogen will cause the bulbs to produce lots of weak, green leaves at the expense of blooms. The addition of more potash (potassium) will help produce stronger bulbs, which develop stronger leaves and stems.

Sufficient moisture is critical to daffodils—in the fall to help generate good roots before the ground freezes and again in the spring when the flowers are actively growing. Daffodil stems are hollow and when there is enough moisture, the stem is filled with water, which helps to support itself and the flower. If it’s dry and the stem is hollow, it is more likely to buckle under the weight of the flower.

Leaves emerge fine but quickly discolor and die

Let it be a lesson this fall: If drainage is not perfect, don’t plant bulbs there.

In these cases, the plant also fails to bloom. Bulb rot is often the cause, and poor drainage is the most common contributor to rot. Dig out the suspect bulbs. If the bulbs or roots are discolored and have soft or foul-smelling areas, dispose of them in a hot compost or by burning. Improve the drainage in that area, raise the bed, or switch to plants more tolerant of wet soil. For instance, quamash (Camassia) is generally more tolerant of moisture than tulips.

Failure to exit gracefully

Plan in the fall for a better ending to next spring’s show.

Gardeners love bulbs’ spring show but often hate the clutter factor—the leaves’ prolonged fade. Yet foliage can be clipped away earlier than you may think, if a plant is already full enough. If all you ask is that a plant replace itself each year, not increase its clump size, cut back tulip and daffodil foliage as early as June 1—about two months after the plants emerge from winter rest. If such plants don’t bloom as well the next year, stall that year’s cut by two weeks or replace them with a variety that can put up with our impatient ways.

However, it is simplest to let bulb foliage die back naturally. You can allow this yet reduce the visual distraction by pairing bulbs with late-emerging perennials such as hardy hibiscus (Hibiscus moscheutos) or blue mist flower (Conoclinium coelestinum), or self-sowing annuals such as balsam (Impatiens balsamina) or spider flower (Cleome).

Beneath this kousa dogwood are hundreds of squill (Scilla siberica) that color the lawn blue in April and then are mowed down when lawn clipping begins. Here in late April the squill leaves still show like coarser blades of grass. Even easier, for both gardener and tree: Smother the lawn and then plant the late-emerging, August-blooming groundcover hardy plumbago there (Ceratostigma plumbaginoides) to cover the squills' exit. — Beneath this kousa dogwood are hundreds of squill (*Scilla siberica*) that color the lawn blue in April and then are mowed down when lawn clipping begins. Here in late April the squill leaves still show like coarser blades of grass. Even easier, for both gardener and tree: Smother the lawn and then plant the late-emerging, August-blooming groundcover hardy plumbago there (*Ceratostigma plumbaginoides*) to cover the squills’ exit.

Article by Janet Macunovich and photos by Steven Nikkila, www.gardenatoz.com.

ELSEWHERE: Naturalizing spring flowering bulbs

Janet’s Journal: Garden design common questions—and answers

April 27, 2022 • Leave a Comment

A unique garden design is a common goal. We all ask the same questions and then go our own ways with the answers. Here are the questions I hear most often, with no-frill answers that you can personalize.

classic-classy-garden-design — Classy, classic, and easy are three things to aim for in planning your landscape. The lowest-care parts of a landscape are beds filled with shrubs and groundcover. Here, *Spirea* ‘Gold Flame,’ dwarf summersweet (*Clethra alnifolia* ‘Hummingbird’) and vinca.

What can I plant for the most color and lowest maintenance?

Plant what will thrive in that spot. Avoid what will merely survive. Say no to what will only “tolerate” those conditions. Only when it thrives can a plant be all it can be and take care of itself.

Make the most of experts by taking a list of your site specifics (see the sidebar “Matching plant and site”) to your local garden center and asking for plant possibilities. Then sit down with books or at your computer, search for images and descriptions of those plants, and decide which you will like best. And, where possible, make sure to purchase the plants from the experts who helped you.

Choose only a few, because less is more when it comes to visual impact and low maintenance. Focus on the shrubs and low groundcovers, since plantings heavy on those two elements are the simplest to maintain. Do not make your choices based on flower color but on foliage—flowers last only weeks but gold, gray, maroon, white-edged, or blue-green leaves are there all season, even all year. After foliage, go for naturally crisp plant shapes and non-floral color such as bark or berries.

carpet-juniper-zebra-iris-blanket-flower — Carpet juniper, zebra iris (*I. pallida* ‘Argentea Variegata’) and blanket flower (*Gaillardia*) are all well-suited to full sun and sandy soil. Space is also an important part of this combination, and is a feature sorely missing from many landscapes.

Matching plant and site

To make a great match, fill in the blanks or circle the appropriate terms to describe your site. Choose or keep only those plants that fit every category.

Sun: A plant there will cast a crisp shadow for ____ hours each day. More than 6 hours = full sun. Less than 4 = shade.

Soil: The soil is _________ (terms from below that apply)

Sticky (clay)
Gritty (sand)
Dark (rich)
Pale (lean)
Well-drained (18-inch deep hole filled with water empties within 24 hours)
Moist, even days after a rain
Dries out quickly
Loose, airy

Irrigation: Is _________ (terms from below that apply)

Readily available/automatic system
By hand the first year, then rain-only

Exposure: ____ (yes/no) the plant may have a greater than average chance of having to deal with frost, strong wind, exhaust gases, pool splash, pet/child contact or destructive animal(s) including _________.

Resources that list plants by site or provide detailed site info:

Landscape Plants for Eastern North America, Harrison Flint
Native Trees, Shrubs & Vines for Urban & Rural America, Gary Hightshoe
Manual of Woody Landscape Plants, Michael Dirr
Perennials and Their Garden Habitats, Richard Hansen & Friedrich Stahl
Perennial Reference Guide, Karleen Shafer & Nicole Lloyd

What are some fast-growing trees? We need shade!

Take care in what you ask for. There are good, fast trees (see the sidebar “Shade trees that grow quickly”) but even the best tend to be very large when fully grown, have weaker wood, and host more insects than trees that grow more slowly. Shading a table with an umbrella or covering a sitting area with a pergola or pavilion can give you shade while you wait for a slower species.

If you do plant for speed, give the tree lots of room. Think twice about using such a plant to shade areas where twig shedding and insect fall-out would reduce the tree’s worth. Where space is limited, planned obsolescence is a good strategy—plant one fast tree with a slower tree nearby, letting the speedy one serve for just 10 or 15 years while the other bulks up.

lacebark-elm-ulmus-parvifolia — LEFT: Lacebark elm (*Ulmus parvifolia*) is an excellent choice when fast growth is a priority. This tree at Dow Gardens in Midland, Michigan is just 20 years old and over 30 feet tall. RIGHT: Lacebark elm not only provides shade, its bark adds interest in the landscape.

Shade trees that grow quickly

Catalpa
Ginkgo (fast in youth) – Fruitless/male varieties such as ‘Autumn Gold’
Katsura (Cercidiphyllum japonicum)
Lacebark elm (Ulmus parvifolia)
Poplar (Populus hybrids) – Male, disease-resistant cultivars such as ‘Eugenei’ and ‘Assiniboine’
Red-silver maple hybrids (Acer x freemanii) such as ‘Autumn Blaze’
River birch (Betula nigra)
Thornless honeylocust (Gleditsia triacanthos var. inermis)

How can I make my doorway look (better, more inviting, classier, more colorful, etc.)?

Spaciousness is what’s inviting, refreshing, most complementary of architecture around an entry, enduring—and most often missing in modern landscapes. So plan for equal amounts space and plants at an entry. Give every plant or group of like plants room so that even at maturity it will not touch its neighbors. You can “color” the space between plants with mulch or a very low groundcover.

Choose only what will thrive on the site and strive for calm combinations. A pleasing trio is plenty (see the sidebar “Making great combinations in the landscape”). To place a combination, look at your door as if you are a guest just pulling into the driveway or starting up the walk. Fill that person’s whole view with just one group of plants. If the walkway is long with nooks that are only revealed as a person walks toward the door, or your yard is large enough that you can turn your head to see another view that does not include the door, plant a second combination.

Within the landscape, repeat or give a nod to something in the architecture of the entry. For instance, if the door is painted an accent color, echo that in foliage or pottery. If there is a distinctive shape in windowpane, gable or trim, carry that out into a bench, trellis or sculpted plant.

dwarf-blue-spruce-picea-pungens-kosteri — If the door is painted blue, or the architecture features copper gone to verdigris, a dwarf blue spruce (such as this *Picea pungens* ‘Kosteri’ which the author prunes annually to keep it from growing too large for its place in this landscape) is a good choice in a combination of plants for that entry landscape.

Making great combinations in the landscape

pigsqueak-bergenia-cordifolia-sweet-woodruff-galium-odoratum — Combine plants that will thrive on the site and which have some complementary features so that your landscape will have interest even when there is no bloom. Coarse, evergreen pigsqueak (*Bergenia cordifolia*) punctuates a mass of sweet woodruff (*Galium odoratum*), a low-care, six-inch groundcover for part shade.

Combine for natural shape, foliage color and texture. For example, fine-textured carpet juniper ‘Mother Lode,’ fine-mounded barberry, and coarse-textured, vase-shaped smoke bush. For more subtlety, downplay the contrast between elements—make it a ‘Gold Nugget’ barberry with ‘Mother Lode’ juniper and the green-leaf American smoke tree. For more drama, increase the contrast by using ‘Crimson Pygmy’ barberry or purple-leaf smoke tree.

Evaluate the seasons of special interest provided by a combination and begin additional groups with an eye toward filling seasonal gaps. The juniper-barberry-smoke tree combination provides winter interest, particularly vivid spring foliage effects, and July bloom. So a second group might include a June-blooming tree lilac, ornamental grass that turns red in fall and an attractive, winter-hardy planter that can showcase a summer-blooming annual.

What can I plant that grows quick, for privacy?

Fences grow faster than hedges. Where traditional fencing is not allowed or doesn’t fit the overall picture, use individual sections of fencing or near-solid trellis, strategically placing them between the viewer in your landscape and intrusive elements outside your yard.

Stick with classic hedge material for screening. Those in that category are dense, look good even if sheared, and are dependable across a variety of growing conditions so that they maintain a uniform appearance even when stretched across a property. Privet, boxwood, yew, spirea, burning bush, arrowwood viburnum, barberry, hornbeam, and arborvitae are classics.

Do not crowd a hedge as you plant. Leave room between plants so that roots and new branches can develop in those spaces, or you will probably experience mid-hedge plant losses, uneven growth, and pest problems throughout the life of the hedge.

hedge-collection-morton-arboretum — At hedge collections, such as this one at the Morton Arboretum in Lisle, Illinois, we can see many different trees and shrubs clipped as hedges. There is also a lesson to be learned by noticing which species the planners deemed reliable enough to hedge behind the entire collection, through sun and shade: burning bush.

What can I plant to soften the corner of the house?

Be clear in your definition of “soften” when you ask a designer this question. If you mean to interrupt lines that seem too straight or unnatural when seen as part of a landscape, choose a plant with a naturally rounded or irregular form and place it where just part of that plant will overlap a segment of the offending line. Don’t crowd the building and don’t repeat or cover the entire line.

So if it is the vertical line of the house wall you wish to soften, you might position a small, round-topped crabapple such as Sargent, so that one side of its mature canopy will cover part of the wall’s edge. Place the tree so that a person in your primary viewing location will see the trunk as well away from the house—not lined up with that vertical wall edge. If the horizontal line where your house meets the ground is the part of the corner you want to moderate, plant a low, coarse groundcover such as perennial forget-me-not (Brunnera macrophylla) along one portion of that line but do not repeat the entire line with the groundcover.

Sometimes when a person says they wish to soften a corner, they mean to lead the eye less abruptly from an overly large house to the ground. That usually requires a horizontal space apparently as wide as the house wall is tall. This can be accomplished with a deep, wide bed extending from the house out into the yard, or with an island in the lawn. In either space, use plants of graduated size to create a skyline beginning at the height of the eaves and descending to the ground.

sargent-crabapple-malus-sargentii — Sargent crabapple (*Malus sargentii*) is a small tree with a naturally wide, low crown (here, pruned to sharpen that natural form) and tiny, abundant fruit that hangs on through winter. It’s a long-interest, low-care element that a smart designer finds by giving features such as shape and berry color more weight than bloom.

What should I plant in the space between the house and the front walk?

Usually, less is best in these spaces which were created by builders, not gardeners. Fill such a space with a mass of low groundcover or with long-interest perennials (see the sidebar “Long-interest, front-walk perennials”). Avoid filling it with shrubs, most of which will outgrow that space unless continually pruned—that means more work and less natural beauty.

If the area is large, punctuate the groundcover with something like a sculpture, a neat clump-forming perennial, a group of boulders, a sinuous and rocky dry stream bed, a lamp, or birdbath. Place the interruption(s) with care so they fit the feel of the overall landscape. A center placement or a line of equally-spaced, matching items works in a formal setting. One off-center item or three similar but unequal items placed to describe an unequal triangle will work better where informality and asymmetry are the rule.

Avoid confusing plantings in this area with “something for the front of that wall.” Do this by keeping your main viewer’s location in mind—if you are in the street, on the public walk, or looking in from the foot of the driveway, anything between you and the house will appear to be in front of the house. Plantings outside the front walk or in the lawn can fill that visual space more gracefully and without the increased work required to maintain plants in small spaces.

shrubs-in-narrow-space-between-house-and-walkway — **It’s not necessary to plant shrubs in that narrow space between house and walkway. What’s planted *outside* such a walkway can adorn the house just as well.**

flame-grass-miscanthus-sinensis-purpurescens-autumn-joy-sedum-carpet-juniper-hicks-yew — To the viewer from the road looking toward the house, plants in that bed outside the walkway fill the space “in front of” the building. Flame grass (*Miscanthus sinensis* ‘Purpurescens’), ‘Autumn Joy’ sedum, and carpet juniper in front of Hicks yew.

autumn-joy-sedum-blooming — **‘Autumn Joy’ sedum has a neat appearance before blooming in August. It continues to look neat and colorful through fall and even into winter. That qualifies it as a good front-line perennial.**

Long-interest, front-walk perennials

For high-profile places, mass perennials that look neat when not in bloom, have an attractive winter presence, and require minimal care. Examples:

Bigroot perennial geranium (G. macrorrhizum)
Blue oat grass (Helictotrichon sempervirens)
Coral bells and foamy bells (Heuchera and Heucherella varieties)
Lenten rose (Helleborus x orientalis)
Tall stonecrop (Sedum including ‘Autumn Joy’)

How can I hide the (utility box, air conditioning unit, trash cans, well head, etc.)?

Distract the viewer by providing something nice to look at along a different line, then incorporate the unfortunate element within plants or features that frame the more desirable feature. For instance, where a utility box begs attention, you might place a substantial birdbath or decorative scarecrow in the foreground to the left or right of the utility box, then plant a mass of low, dense shrubbery such as dwarf spirea or deutzia to embrace or surround your chosen whimsy. Let that frame swallow the utility box or cross between it and the viewer, obscuring it.

Alternatively, embrace and multiply the ugly feature. Where there is a wellhead that catches your eye, plan to cover it with a fiberglass boulder, but put that rock in a bed that has several clusters of equally or more impressive native stone. Be careful to avoid drawing the bed to center on the wellhead.

As another example of hiding something in plain view: If a square of concrete marks a septic tank cover and irritates your aesthetic sensibilities, give that concrete a crowd to blend into. Add flagstone or concrete stepping stones in a pleasing pattern across the lawn.

purple-weeping-beech-fagus-sylvatica-purpurea-pendula-picea-abies-nidiformis-autumn-joy — Hide a distracting feature such as a wellhead by placing something more attractive to one side (purple weeping beech, *Fagus sylvatica* ‘Purpurea Pendula’), then massing bird’s nest spruce (*Picea abies* ‘Nidiformis’) and ‘Autumn Joy’ sedum as a frame for the tree that just happens to conceal the wellhead.

What can I plant along the edge of the deck/patio?

Gardens are least expensive and simplest to tend when they are close at hand, so if you want a flower garden, put it here. However, don’t plant it right along the edge of a deck or patio if you cannot see that area from your lounge chair. Narrow borders hidden from everyday view along the foot of a raised deck or patio should be filled with groundcover or simply mulched to reduce weeding and edging chores, and a separate garden placed far enough from the edge to be easily seen and enjoyed.

Use tall features carefully around a sitting area since large, dense objects can block breezes and light, creating an oppressive or claustrophobic atmosphere. Position shrubs or a trellis to block unsightly views but do not mass them or use species so massive that they must be kept sheared.

clematis-viticella-boxwood-liriope-oakleaf-hydrangea — A good place for a garden is close at hand, so areas next to a patio are great garden spots. Clematis on a trellis (*Clematis viticella*), boxwood, and variegated lily turf (*Liriope*), oakleaf hydrangea (*H. quercifolia*), and hostas.

Where can I get the cheapest plants?

Cheap plants are not what you need! Look for the right plants in an affordable size at a garden center that produces healthy plants. Make a list of the plants you’ve decided to use—include the scientific name and variety—and take that to a local garden center.

Small, healthy plants grow more quickly than anyone expects. If you planned combinations for pleasing contrast and then tighten the spacing between plants of the same kind to leave a bit more space between groups than between plants of one kind, even small plants have immediate, pleasing impact.

Don’t rush as you landscape. It’s a long-term investment, so take one question and develop one lasting solution at a time.

Article by Janet Macunovich and photos by Steven Nikkila, www.gardenatoz.com.

Your plants survived winter—only to be snuffed by spring?

March 21, 2022 • Leave a Comment

How to help your plants make it through the frosty weeks of April

by Janet Macunovich
Photographs by Steven Nikkila

Plants are most susceptible to cold after they begin to wake up in spring. Buds, bark and roots that were hardened to the point of being able to weather minus 20 degrees in January become irreversibly soft by late March or early April. Then they may be seriously damaged at 25 degrees and killed outright at 10 degrees. Sudden, large drops in temperature hurt them most, and that’s what April frosts usually are—frigid packets of air that drop from clear skies after a balmy, slightly breezy day goes still at sunset.

A magnolia hardens its tissues in late fall and winters its flowers under fuzzy bud caps capable of withstanding minus 15 degrees. Yet once the sap begins to flow in the tree and the bud caps split open, the flowers may be damaged by frost. It’s not practical for home gardeners to protect trees from frost, but this article has tips on how to help other plants past this most treacherous of times.

**Frost damaged some petals on this saucer magnolia (*Magnolia x soulangiana*). The damage won’t hurt the tree, but it can spoil its show.**

Consequences of spring freezes may take days or even weeks to develop and are often lumped in with “winter kill.” We may even fail to recognize them as cold damage because they appear long after we’ve forgotten the frost. Then we see leaf drop, bud blast, aborted flowers, splitting bark, scorched foliage, freeze-dried twigs, stunted growth, susceptibility to disease, and failure to flower or flourish.

We often spend hours in late fall putting special plants to bed with wilt-stop coatings, burlap screens, elaborate mulch blankets and one last watering before the ground freezes. Those measures may have made a difference—that marginally hardy rosemary may have survived in its protected alcove and the rhododendrons and boxwoods stayed moist enough to bring their leaves into April unscathed. Yet what’s alive right now may be relegated to the compost pile and labeled “not hardy” if we let down our guard during this last leg of the journey.

Here are ideas to help your plants pass without harm through these next few, most risky weeks.

**Oakleaf hydrangea (*H. quercifolia*) is another plant that must carry its tip buds from one summer right into the next in order to bloom.**

Once that densely coated bud cover opens, I try to protect the emerging hydrangea shoot from freezes. If that bud dies, I’ll certainly see the plant’s pretty foliage this year but probably won’t see any bloom.

Moist soil makes a warm night.

You can fight frost with water, but you’ll have to aim the hose at the plants’ roots, not up at the leaves and stems.

An inclination to sprinkle at-risk foliage is understandable if you have seen nursery stock or an orchard protected from spring frost in rather dramatic fashion, by sprinklers that run all night to coat the plants with ice and all morning to ease the ice’s passage. However, this technique is one that warrants a “don’t try this at home” caption. That’s because it’s the creation of ice, not its simple presence, that works the magic. Plants benefit from the heat given off by each new drop of water as it enters an icy state. Standard oscillating and rotating sprinklers can’t deliver the amount of water or relentless coverage needed to foster continual ice formation.

What you can do with water is to stoke the radiator below each plant. Keep an eye on the three-day forecast so you can tend your plants the day before a frost is due. Soak the soil—avoid splashing the branches and foliage. Moist soil absorbs more heat from the air by day and radiates it longer and more steadily into the night than dry soil. That’s one reason that frost is always more likely over sandy ground than clay.

Don’t over-do. If your garden is very well-drained, you may be able to water with abandon but if there’s any chance the soil will become waterlogged, quit. Soggy roots are more trouble to a plant than frosted tips.

Everything’s warmer under a tent.

Everyone knows that heat rises but many are surprised to know just how much warmth can radiate from the soil. Soil temperature in the Midwest in late winter and early spring may be in the 20s or perhaps 30 degrees from ground level to two feet deep. Below that the ground remains at about 50 degrees. If the soil is loose and airy, that heat rises steadily through and out of the soil. It can preserve plants and plant parts close to the ground during a frost.

Cover a plant with something that seals its connection with this radiator. Within that tent the air may be 5 degrees warmer than in the open.

Fiber makes a great frost blanket.

Don’t use plastic to cover plants, or if you do, place props to hold it well up off the leaves and twigs so it can trap ground-warmed air around all parts of the plant. Since plastic is such a poor insulator, any bit of plant touching the plastic is essentially in contact with the frosty air and likely to freeze as if unprotected.

The better choice for frost protection is cloth, replete with tiny air pockets. You can use old linens and blankets if they’re light enough to cover without crushing delicate foliage. To use heavier materials, first place props to bear the weight.

Lightweight fabrics developed specifically for plant protection are called floating row cover, frost blanket, frost cloth, plant cover, and spun-bond polypropylene—all with various brand names. These products are light enough in most cases to be supported by the plant itself and come in sections or rolls wide enough to cover a shrub or a whole bed of flowers or vegetables. Permeable to light and water, they can be left in place even on cold days without smothering the plant they’re protecting. They are made in a range of weights from about one-half to several ounces per square yard. In general, the heavier the cloth the more light it blocks, but the more heat it can hold—the lightest promise just 2 or 3 degrees of frost protection while the heaviest claim eight.

Floating row cover protects newly planted bear’s breeches (*Acanthus mollis*) during a frost. Lenten roses (*Helleborus x orientalis*) in the foreground require no protection from this frost because they’ve developed in place and are in sync with normal weather. The newcomer has just come from a greenhouse and is beyond the stage of growth it would be if it had grown on-site.

**Frost protection should be removed once danger of frost has passed, to avoid overheating covered plants.**

It’s a cloche call.

The traditional cloche is simply a large glass jar that can be inverted over a plant. More recently, sections of glass or plastic clipped together to make tents over individual plants or rows have been included under this term.

Plastic tunnels covering rows of plants are sometimes called cloches, too. They’re made by bending heavy wire into big U shapes, sticking them upside down into the ground, and then covering them with plastic from a roll. Glass is better than plastic in terms of the light, warmth and humidity it affords a plant, but shatterproof plastic is safer for garden use. Plastic cloches can provide protection from hail as well as frost.

Plastic milk jugs and soft drink bottles can be pressed into service as cloches. Cut off the bottom of the jug or bottle and press it firmly into place as you cover the plant so its cut edges sit securely in the soil. If days are warm, remove the bottle cap to vent excess heat.

A modern twist on the traditional cloche are season extenders like the Wall O’ Water. A plant is encircled by this cylinder of compartmented plastic—basically a double sheet of heavy plastic seamed to form pockets that can be filled with water. The water absorbs radiant energy by day and at night releases it to the plant in its embrace.

If you have special small plants and an abundance of two-liter soft drink bottles, you can make your own wall of water. Cut the bottom off one bottle and circle that container with six intact bottles. Use duct tape to hold the group together. Slip the center bottle over a plant. Remove that bottle cap if days are warm, to prevent heat build-up. Fill the surrounding bottles with water.

Gracious sakes, come in outta that wind.

Our mothers, grandmas and aunties were right—one can catch one’s death in a wind. Cold that wouldn’t otherwise harm a plant can kill if drying winds accompany it. Wind is even more damaging to plants during early spring cold spells than it is during the depths of winter. So keep that burlap screen or snow fencing in its place several feet to the windward side of your broadleaf evergreens.

One reason spring wind is so devastating is that air temperatures during the day are warm enough that a holly, rhododendron, boxwood, pieris or grapeholly leaf can sustain photosynthesis. Those leaves lose water through their pores during that process. Yet a cold snap can freeze the top inch of soil where these plants have many fine roots. The next day, the plant sits in the sun losing water through its leaves but the water the roots need to replace it is locked in ice. When water runs short, the losers are the aerial parts furthest out—tips and emerging buds—as well as leaf edges that have “softened” as they quit the devices that added up to seasonal hardiness. We often don’t see the damage until May, but the scorched tips and leaf margins we see at that time began in that April freeze.

If you wonder whether you should protect plants from wind, look around your neighborhood for trees that stand alone, away from the protection of a grove or any buildings. Are those trees symmetrical or distorted? Distortion on one side can indicate severity and direction of the prevailing winds that dry and kill in late spring.

Cover those feet.

Mulch is a another strategy that’s important to understory species with shallow roots, such as rhododendron, holly, Japanese maple and magnolia. A study in Wisconsin put a number on the value of mulch. That is, when air temperature falls to 1 degree, the soil there drops to 16 degrees if it has a three-inch mulch blanket, but can stay at about 22 degrees given six inches of cover.

If you begin to rake off special plants’ extra mulch on warm spring days, don’t be too quick to cart it away. A friend has recently recommended sawdust as a material that can be easily peeled back yet replaced in a hurry. I intend to keep some on hand to rectify the silliness of Japanese wax bell (Kirengeshoma palmata), which is forever leaping up too soon and being cut down by frost.

What gardeners do best: Improvise.

I don’t have many things that I keep on hand especially for frost protection. Like most gardeners, I improvise. Upended plastic garbage pails, five gallon buckets, milk crates, old draperies and cardboard boxes are all in my April bag of tricks. I’ve also grinned over the use of beach umbrellas in one friend’s garden and discussed with another how we might use a hunter’s open-bottom ground blind to protect shrubs and even small trees.

Thank heaven for plants that just take what Nature hands them and keep on chugging. These Red and Yellow Emperor tulips have reckoned with snow and frosts for 20 years, even freezing solid in a late April snow.

Here they are just one day after appearing in the previous, snowy scene. So long as I don’t walk on them while they’re frozen—an abuse resented by all plants from lawn grass to wisteria vines—they come back with gusto.

Dream of ideal plants and places.

Every spring I vow to eliminate all plants that cause me extra work. Every summer at least a few of them convince me anew that they’re worth the effort. Thank goodness for the existence of perfect plants—species that can handle whatever “normal” happens to be each spring. I’m grateful, too, for ideal places, such as that wind-protected spot about ten feet southeast of my neighbor’s six-foot hedge. It is ground that happens to slope to the southeast so it sheds cold air downhill and catches warming sun early in the year. It’s sandy, well-drained soil there, so it conducts ground warmth well and doesn’t add oxygen deprivation to a root’s winter woes. I can’t ask for more protection.

But I can ask why the spot’s not bigger. I’d like to put my whole garden into it.

Article by Janet Macunovich and photos by Steven Nikkila, www.gardenatoz.com.

Proper planning ensures reliable spring bulbs

September 2, 2021 • Leave a Comment

Each year I plan, purchase and plant thousands of bulbs. Here’s what I’ve learned to do in fall to insure the best show of spring bulbs.

**In early April, all eyes will be on this blooming cornelian cherry tree (*Cornus mas*), or gazing at the yard art. Plan the bulb planting scheme in the fall to highlight those attractions.**

Think “grocery produce section” when selecting bulbs

When you choose bulbs in person at the local garden center, you have a significant advantage: you have direct control over quality. Make the most of it. Pretend you’re at a grocery store choosing vegetables, because that’s what bulbs are—root crops.

You would think twice about buying a mushy potato, rubbery carrot or shriveled onion. Be just as choosy with bulbs. Select for firmness and even color. Check for soft spots that may be on their way to rotting, and reject bare-root ephemerals like foxtail lily (Eremurus) if they have broken roots. Take the largest of any bunch.

Keep the same mindset if you must store bulbs before planting. If the bulb has a tunic (a papery skin as on a tulip, daffodil, crocus, etc.) or a horny surface (such as snowdrops and spring-blooming anemone), store it cool and dry like you would store onions or garlic. If it does not have a protective covering, like a true lily or a bare foxtail lily root, keep it as you would carrots—cool and humid in a refrigerator crisper drawer or root cellar. If it’s wrapped, make sure that condensation doesn’t collect and puddle inside to incite rot on the surface of the bulb or root.

About price: Bargain basement bulbs are usually disappointing. If you buy the cheapest, you’re almost certain to receive bulbs half the size of premium items. They may be dry and wasted from improper storage. Given years of ideal conditions, such bulbs may produce a decent display. Next spring, however, they’ll present flowers few and small.

Beware of low-priced collections too. Whether of mixed varieties of one species or a “spring collection” of different species, they rarely live up to their promise. The catalog may illustrate a mix of six types of daffodil or tulip yet ship just 5 of the fancier types to each 45 of a pale, small-flowered type. The mixed-species collections often contain only a few of each big, showy species (hyacinths, daffodils, tulips) but many of each minor bulb (squill, winter aconite, glory-of-the-snow, etc.). They sometimes include downright weedy species such as star of Bethlehem (Ornithogalum umbellatum).

Far too often, the tiny, early bulbs are overlooked when we plan and plant in fall. Yet masses of any of this collection can be planted to naturalize most anywhere in a landscape. Flowers, from left: White *Puschkinia* with its baby blue stripe accompanies early daffodil ‘Jack Snipe,’ fading away as lamium covers that ground. Blue squill (*Scilla sibirica*) plus the blue and white forms of woodland anemone (*Anemone blanda*) are great partners with the evergreen perennial lenten rose (*Helleborus* x orientalis) under a kousa dogwood. Blue ‘Harmony’ and standard purple iris (*Iris reticulata*) can mix it up with yellow crocus (*Crocus chrysanthus*) among clumps of blue fescue or perennial fountain grass.

Include early-, mid- and late-blooming types

You can enjoy spring bulb bloom from early March until early June. Most crocuses come early in that line-up, followed by Dutch hyacinth and daffodils in April, and tulips from late April into May. Alliums, foxtail lily and others carry the show into June. Within each group, however, there are early-, mid-, and late-blooming species and varieties. Take the time in fall to plan a mix that will give you spring color every week that’s important to you. (See the sidebar “Parade of bloomin’ bulbs” for a starting line-up.)

Short on space? You can plant two, three or even four kinds of bulbs in one area if you choose for separate seasons and give all players elbow room. For instance, I have planted squill, early species tulip (Tulipa kaufmanniana), checker lily (Fritillaria meleagris), and drumstick allium (Allium sphaerocephalon) in one spot. I excavated that bulb area about 10 inches deep and placed the tulips, then added a few inches of soil and set the checker lilies and drumstick alliums. Finally I added another inch of soil, scattered the squill and covered it all with the rest of the soil.

There’s no right or wrong in bulbs or any other aspect of gardening, just different ways for each gardener and garden. A catalog may recommend 188 Grecian windflowers (*Anemone blanda*) per square yard, and you certainly can plant that many for immediate impact. Yet you can also place just a few near your favorite garden sculpture and watch them multiply over the years.

Plant them where you’ll see them

Before you plant, stand in the windows you use most in late winter and early spring. Look at your garden from there and from the driveway where you enter and exit. Plant spring bulbs where you will be able to see them from these vantage points or you’re wasting your time and money.

Bulb color goes a long way—if you can see it. So it’s a smart move to plant daffodils where you will see them each day as you leave and come home again. Never forget as you make your choices, however, that most spring bulbs need full sun to bloom well. Note the difference here in the amount of bloom between the daffodils in the wooden barrels and those in the beds. Those in the barrels were sun-grown in pots and moved into the planters for temporary show. Those in the beds have grown there for years, shaded most of each day.

Plant them deep

The rule of thumb for bulb depth is to set a bulb with soil over its nose 2 to 3 times as deep as the bulb is tall. That means to plant a tulip, daffodil, lily or large allium, you need a hole 8 or 9 inches deep. That will accept the three-inch bulb plus at least six inches of soil above it. Most people plant shallow and pay for it in frost damage, toppling flowers and blooms that come one year then never again.

I plant even deeper than recommended. I put large bulbs in holes at least 11 inches deep. If the drainage is good, they don’t mind at all, and need dividing less often. Plus, I won’t harm them as I garden because they’re all below the reach of my nine-inch spade blade.

Doubtful? Experiment with just a few bulbs planted deeper this fall. Note what you planted deep, where, so you can gauge the results next spring. I still do, since I’m not sure I’ve pushed it to the limit, in terms of depth. One fall, after planting a dozen tulips a foot deep, I forgot all about them and later dumped a wheelbarrow of soil there and topped that with a leftover bale of straw. The next spring, the tulips grew from a foot down, through the piled soil, plus 14 inches of baled straw to bloom cheerily above the heap.

That just goes to show that there’s no absolute right or wrong when it comes to using bulbs or any other aspect of gardening. Take that to heart as you plan and plant bulbs this fall. Have fun, and enjoy the surprises spring will bring.

Parade of bloomin’ bulbs

Here’s a list of which bulbs are likely to bloom when, with what. To use it, remember it’s only a guide—winter and spring weather can slow one bulb and speed another—and adjust for length of growing season. It’s geared to use in northern zone 5, where the growing season starts later than it does in a more southern zone 5 but earlier than on the Lake Superior shore zone 5. So change mid-March to early March if you’re in zone 6, or to late February for a zone 7 North Carolina winter home.

Very early (by mid-March): Snowdrops (Galanthus), early crocus (Crocus sieberi, C. minimus, C. tommasinianus), danford and netted iris (Iris danfordiae, I. reticulata).

Early (late March to mid-April): Grecian windflower and wood anemone (Anemone blanda, A. nemerosa), squill (Scilla sibirica), Puschkinia libanotica, Dutch crocus, Dutch hyacinth, early- and mid-season daffodils, firespray- and tarda tulips (Tulipa praestans, T. dasystemon), glory-of-the-snow (Chionodoxa).

Mid-season (late April and early May): Late daffodils, early tulips (Triumph, Foster, multi-flora, and Greigii tulips followed by lily-flowered and fringed types), western trout lily (Erythronium ‘Pagoda’), checker lily (Fritillaria meleagris), summer snowflake (Leucojum‘ Gravetye’), grape hyacinth (Muscari).

Late (mid- to late May): Late and parrot tulips, species tulip (Tulipa wilsoniana), quamash (Camassia), large-flowered alliums, sego lily (Calochortus), perennial glads (Gladiolus byzantinus), bluebells (Hyacinthoides campanulata).

Very late (end of May and into June): Sicilian honey lily (Nectaroscordum siculum), foxtail lily (Eremerus), drumstick and blue allium (Allium sphaerocephalon, A. caeruleum), California hyacinth (Triteleia laxa, Brodiaea).

Article by Janet Macunovich and photos by Steven Nikkila, www.gardenatoz.com.

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Create your own allergy-free garden

April 5, 2021 • Leave a Comment

Select the right plants to reduce allergies in the garden

Do you enjoy seeing plants like this beautybush (*Kolkwitzia amabilis*), watching the butterflies and hummingbirds that sip its nectar, or smelling its sweet fragrance? Or do you or someone you know have allergies that force you to keep distance and windows between you and the garden? Here’s some help, in the form of hypo-allergenic plants, materials and techniques.

Does garden work make you sick? Literally? Or is there someone else in your life who can’t breathe freely in the presence of plants and other garden materials? If so, give yourself or that other a break. Change your plant choices, planting arrangements and work habits now to reduce your garden’s allergy irritation quotient.

A sizable portion of the U.S. population suffers from allergies. Many of the afflicted are children, but adults are learning, to their surprise, that these conditions can develop even late in life. To some of these sufferers, their allergies are only low-level nuisances. Others face more serious symptoms. Every one pays some cost and makes compromises to get by.

Spot allergy offenders before they’re under your nose

The word pollen comes from the Latin for “dust.” When it’s airborne, pollen can be a potent allergen. However, not all plants produce pollen and not all pollen floats in air. People with hay fever are wise to look for pollen-free flowers and heavy-pollen plants.

Pollen-free flowers are not common. Pollen is essential for seed formation, so in the natural course of things, every plant species produces these yellow, orange, or other-colored grains on stamens—the “male” portion of a flower. The important thing here is that in some species such as holly, mulberry, kiwi and ginkgo, some individuals in the group make flowers without stamens. These “females” are the seed-bearers of their species, and they are ladies a person with allergies can appreciate. (See sidebar with female and male plant lists: “Battle of the sexes.”)

Wind-pollinated means trouble

The worst kind of pollen is from wind-pollinated plants—”anemophilous” species. Such grains float so they’re easily inhaled, plus the species that produce them tend to go overboard when it comes to amount. Less troublesome is sticky and heavy pollen, produced by plants that rely on insects and birds to carry it around. These heavy pollen “entomophilous” plants also make less pollen than wind-pollinated species. They don’t need clouds of the stuff when they can rely on hungry pollinators to race directly from one flower to the next.

There are several ways to distinguish between wind-pollinated and heavy pollen plants. One is to check lists such as the sidebar in this article: “Most common culprits in pollen allergies.” Another is the shake test. A third involves learning to recognize what bugs and birds find attractive.

The shake test is simple. Shake plants to see where pollen clouds form. Ask someone who does not have pollen allergies to walk your yard every week or two from early April through late June—the months when pollen counts from trees and shrubs are highest—and rattle your plants. Where this raises puffs or clouds of “dust,” you should doubt that plant. Is it one you are allergic to, or a close relative? Is it one many people are allergic to? You might want to replace such a plant with something more innocuous.

Trees, grasses and weeds most to blame for allergies

When doing shake tests, don’t focus on plants with obvious bloom. The plants most often responsible for pollen allergies—certain trees, grasses and wind-pollinated weed species—have flowers so inconspicuous or so different from typical florist flowers that we may think they have no bloom at all. Where birches or pines overhang a patio and coat it with pollen, people who live there often fail to connect plant to powder. Gardeners who bump branches while clipping juniper bushes in spring are often shocked by the puffs of yellow pollen this stirs.

Not all airborne pollen is problematic, and some is much worse than others. Knowing which to look into is a big first step.

The third way to recognize airborne and heavy pollen involves looking at pollinators, flower sizes and form. If you see that many bees or other flying insects visit a particular kind of flower, chances are good that the only way that plant’s pollen moves is on the legs and body of a carrier. Even before you see insects, if you keep in mind that they follow visual clues in looking for food you’ll start to recognize the plants they service—those with big blooms or many small blooms in showy, large clusters.

Some people are allergic to bee stings, and might want to focus on bird- and butterfly-pollinated plants. These generally have flowers shaped like or equipped with deep, narrow funnels where nectar collects as the blooms ripen.

Spotting and reducing non-plant allergens

Although fewer people are allergic to molds and fungal spores than to pollen, these can trigger allergic reactions too. They rise up by the millions every time you rake leaves, turn the compost or disturb a mulch layer.

So hire a helper to rake leaves, or wear a mask when you do that chore. Work on a cool, still day after a rain, when the air is less likely to carry allergens. Let your city or township compost your leaf litter and other yard waste—don’t pile it and mix it in your own yard.

Eliminate or reduce your use of organic mulch such as bark. Switch to gravel mulch, which allows spores, mold particles, and dust to fall down into the spaces between stones. That’s better than having it rest at the surface where it can take off in the breeze that also caresses your window.

Organic matter tends to build up in stone mulch over time, so its ability to absorb troublesome particles decreases over time. Sprinklers splashing on its surface can raise the settled particles, too, so consider trickle irrigation or weeper hoses.

Also, weed seeds settle into that organic build-up, and can be difficult to eradicate without the use of herbicides that you probably should avoid. So plan to replace stone regularly.

If periodic removal and replacement of gravel is beyond your budget, try a triple thickness of newspaper as mulch, held in place with a thin layer of Turface or another of the gravel-like soil conditioners. When such products become gummed up with organics, they can be covered with a new layer of paper and clean Turface. The original layer will mix gradually, harmlessly into the soil.

Replace troublemakers with low-allergen plants and materials

When you remove troublemaking pollen producers, replace them with species that produce less pollen and are pollinated by insects or birds. Double-flowered varieties are often good choices, since what’s been lost in developing those extra petals on a double rose of Sharon (Hibiscus syriacus) or snowball viburnum (V. opulus ‘Roseum’) are the pollen-producing stamens.

Be sure to learn the mature size of each new plant you consider, and place your additions where they can grow without pruning. Pruning is a branch-rustling, mold-raising chore that allergy sufferers should bypass.

Design more dramatically, and build in filters

Two more things to aim for as you place new plants are high contrast and massed effect, so that you can enjoy your landscape even from afar or through glass. Try clumps of red foliage plants near yellow, big-leaf plants in front of lacy leaf or needled species, distinctly shorter items at the feet of taller individuals, and combinations of varieties with distinctive, no-prune shapes.

Focusing on the distance may help you free up the foreground too. Take vines and shrubs away from your windows where they have a greater potential to contaminate your air.

Whenever you can, place windbreaks between yourself and problem plants upwind in your neighborhood that you can’t eliminate. This calls for using binoculars or imposing a little on neighbors as you do more shake tests to identify the plants that may be causing you trouble. The potential pay-off makes it worthwhile. You don’t have to account for the whole neighborhood—tree pollen can carry a long way but most falls within about 50 feet of the source.

Hedges and fences can serve as windbreaks, slowing wind speed on their lee side for at least ten times their own height. Place a windbreak so that it is at least five feet upwind of any place where you plan to sit or work, because the space just downwind of a hedge receives fall-out as the wind slows and is forced to drop its load of particulate matter and pollen.

A mixed hedge of flowering shrubs such as weigela can replace pollen-heavy yews or junipers if winter privacy is not an issue. Place each shrub so it has room to grow to its full size, to eliminate pruning and all its mold-raising potential.

Reduce your work to reduce your exposure

Do all you can to reduce your yard work. Throw a garden party twice a year and invite sympathetic friends to help. Have all the materials lined up and ready, and bring your hired help in that same day.

Mowing spells allergy trouble, so hire that chore out, and replace lawn where you can with no-mow groundcovers. Have the lawn aerated and treated annually with slow-release fertilizer in the cool, still days of late fall so that turf will be fuller and healthier, less likely to harbor weeds such as ragweed.

Choose plants that are well suited for your site, and not susceptible to pests so that they will be healthy without application of fertilizers, herbicides and pesticides. All of these products are potential trouble for people who have already developed sensitivity to pollen, mold or dust.

Work smart when you spend time in the garden

Finally, decrease your risk by working on cool, windless days, and after every air-cleansing rain. Avoid warm, dry, windy days when pollen counts are highest.

While you’re out, cover your arms, legs and neck. Wear a mask if you mow or rake. When you finish working, undress in the garage and leave work clothes and shoes outdoors—one gram of soil may contain thousands of pollen grains. Shower after working, so you won’t transfer pollen grains, mold or spores into your clean clothes or bed. We can love our plants without sleeping with them!

Most common culprits in pollen allergies

Of 250,000 flowering plant species, only about 100 species have pollen that causes us trouble. Pollen allergy, also called hay fever, rose fever or allergic rhinitis, is most often caused by tree, grass and certain weed pollen. Here are some chief irritants, with the worst in bold.

Trees: alder, ash, aspen, birch, box elder, cottonwood (the pollen, not the fluff from female trees!), elm, hickory, juniper, linden, locust, maple, oak, poplar, sycamore, tamarisk, willow.
Grasses: Bermuda grass, bluegrass (Kentucky bluegrass), Johnson, orchard, redtop, sweet vernal, and Timothy grass.
Weeds: artemisias (including sweet Annie), clover (Melilotus species), cocklebur, curly dock (Rumex species), pigweed, plantain, ragweed.

Goldenrod (*Solidago*) has an undeserved bad reputation. The heavy, sticky pollen goldenrods produce is rarely the cause of hay fever, and then only for a gardener who has developed a sensitivity over many years’ exposure and who accidentally wipes a pollen-bearing glove across her nose.

LEFT: One pollen-producing male cone on a pine may release millions of pollen grains each year. Other conifers and wind-pollinated plants are also prolific—it’s been estimated that if all of Sweden’s conifers dropped their pollen evenly across that country, each square meter would be coated with 300 million pollen grains. Yet pine, fir and spruce are not high on the list of allergy-inducing plants. RIGHT: Like many plants that spur allergic reactions, ragweed doesn’t look like it’s blooming even when it’s in full flower, as here. Yet jar a stalk and just watch the pollen come out in a cloud!

Don’t count on numbers to gauge allergic impact
It’s not the number of pollen grains that causes trouble but their type and an individual person’s response to that type. A similar number of pollen grains—several million—may fall from one male pine cone or one dangling birch catkin, but fewer people react to pine pollen than to birch. An oak’s tassel-like flower may produce at only half the birch’s rate, and a grass plume releases just 1/20th of the pollen, but those grains have a major impact on the person whose body reacts to oak or grass.

Allergic to one, allergic to a group
When we react to pollen it’s actually a response to particular proteins on the surface of that pollen grain. A body allergic to a particular pollen protein often reacts to that protein in other, unrelated substances. For instance, birch pollen is a very common cause of hay fever. People allergic to birch often have food allergies involving hazelnut, almond, walnut and apple.

Recognizing wind-, insect- and bird-pollinated flowers

**If you see bees on a flower like this aster, it is almost certainly an insect-pollinated species. Bees are too busy to take time to smell the flowers!**

**Hummingbird- and butterfly-pollinated flowers tend to be tubular and require a hovering approach, like this cooking sage (*Salvia officinalis*).**

**The tiny flowers that open on these ornamental grass plumes will dangle in the breeze, all the better to spread their pollen.**

Wind-pollinated flowers give themselves away with their inconspicuousness and dangle. Most lack petals, which would interfere with the wind reaching the pollen grains. Most dangle from the plant’s top or upper branches, the better to be caught by a breeze.

Insect-pollinated plants tend to have visually attractive blooms—brightly colored, large or clustered. Pollinators such as bees, flies and butterflies home in on the ripe flower’s color and form. Wide petals or clustered flowers afford the insects a landing pad. Examples: apple (crabapple and other fruit trees), aster, daisy (and many of its relatives), mint (and many of its relatives), rose (and its family), tulip, and yarrow.

Hummingbird- and moth-pollinated flowers are tubular or have narrow nectar-collecting spurs at the bases of their petals. Many require a hovering approach. Bees can’t squeeze into the flower, their tongues won’t reach to the depth of the nectary, or they can’t hover long enough to sip their fill. Examples: beautybush (Kolkwitzia amabilis), butterfly bush (Buddleia), columbine, coral bells (Heuchera), fuchsia, hibiscus, horse chestnut (Aesculus), impatiens, lantana, salvia, trumpet vine, and weigela.

Battle of the sexes

Ginkgo trees, too, have contributed to increased pollen counts in U.S. cities. Seeking to avoid any contact with the rank odor of the female’s fruit, we’re growing and using male ginkgos almost exclusively. In some countries where ginkgo fruit is an important crop, a buyer may have the choice of dozens of named female varieties. In the U.S., if the ginkgo tree you’re considering has a variety name on its garden center tag, it’s almost certainly a pollen-producing male.

Some perfectly good shade tree species, such as Kentucky coffee tree (*Gymnocladus dioicus*) are now adding to the woes of hay fever sufferers in urban areas because we’ve chosen to propagate and plant only male, pollen-producing varieties. Why overload the pollen count this way? So we won’t have to pick up the female trees’ litter—these seed pods, above.

Plants with separate sexes
Examine the plants below while they’re in bloom and you’ll find that the flowers on some never form pollen. A gardener with allergies might choose* those “female” forms and shun the pollen-making males.

Ash tree
Asparagus
Bayberry (Myrica pennsylvanica)
Black gum tree (Nyssa sylvatica)
Box elder
Cork tree (Phellodendron amurensis)
Fig trees (Ficus)
Fringetree (Chionanthus virginicus)
Ginkgo (Ginkgo biloba)
Goatsbeard, perennials (Aruncus species)
Juniper shrubs and trees (Juniperus species)
Kiwi vine (Actinidia kolomikta)
Mulberry trees
Persimmon tree (Diospyros virginiana)
Pistache tree (Pistacia chinensis)
Populus species (cottonwood, poplar, quaking aspen, etc.)
Red maple, silver maple
Sumac shrubs and trees (Rhus species)
Thalictrum species, perennials (meadow rue)
Willow trees and shrubs
Yew shrubs and trees

* Look for a sex-indicative variety name on garden center labels, or the presence of seeds or fruits (telltale of a female). If these signs are lacking, the only way to know the sex of the plant you are growing or considering buying is to inspect its blossoms for the presence or absence of pollen.

Some female, pollen-less varieties of separate-sex species:

American bittersweet vine ‘Indian Maiden’
Bayberry shrub ‘Myda’
Corkscrew willow (Salix matsudana ‘Tortuosa’)
Evergreen hollies such as “China Girl,’ ‘Blue Princess,’ and ‘Blue Maid’
Junipers: Juniperus chinensis ‘San Jose,’ ‘Sea Green’; J. horizontalis ‘Blue Rug,’ ‘Grey Carpet’; J. sabina ‘Skandia’; J. virginiana ‘Blue Mountain,’ ‘Cupressifolia,’ ‘Emerald Sentinel’
Kentucky coffeetree (Gymnocladus dioicus)
Michigan hollies such as ‘Winterberry’ and ‘Sprite’
Red maple ‘Red Sunset,’ ‘Scarlet Sentinel’
Sumac ‘Gro-low,’ ‘Laciniata,’ ‘Dissecta’
Weeping willow (Salix babylonica), most oft-cultivated form is female
Yew ‘Brownii,’ ‘Densiformis,’ ‘Emerald Spreader,’ ‘Fastigiata,’ ‘Repandens,’ ‘Sentinalis,’ ‘Wardii’ (Note: When grown without male company, these females will bear no fruit.)

Some male varieties sold as pollinators or ‘seedless’ forms:

Ash tree ‘Autumn Purple,’ ‘Marshall’s Seedless’
Bayberry shrub ‘Myriman’
Box elder tree ‘Sensation’
Cork tree ‘His Majesty,’ ‘Macho,’ ‘Shademaster’
Cottonwood ‘Colmar,’ ‘Red Caudina,’ ‘Siouxland’
Evergreen holly** ‘Blue Stallion,’ ‘Blue Prince,’ ‘China Boy,’ etc.
Fringetree (Chionanthus) ‘Floyd’
Ginkgo tree, most named varieties including ‘Autumn Gold,’ ‘Princeton Sentry,’ ‘Shangri-la’
Junipers: Juniperus chinensis ‘Pfitzeriana,’ ‘Pfitzeriana Glauca’; J. horizontalis ‘Bar Harbor,’ ‘Jade River,’ ‘Jade Spreader,’ ‘Plumosa’; J. sabina ‘Broadmoor’; J. virginiana ‘Manhattan Blue’
‘Lombardy’ poplar
Michigan holly** ‘Apollo,’ etc.
Mulberry ‘Chaparral’
Red maple ‘Autumn Blaze,’ ‘Autumn Flame,’ ‘Celebration,’ ‘Karpick,’ ‘Northwood,’ (most males are less red in spring than females)
Silver maple ‘Silver Queen’ (you read that right, the queen’s a “he”)

** These species’ males are not the worst of the lot, as their pollen is heavy, rather than wind-borne.

Article by Janet Macunovich and photos by Steven Nikkila, www.gardenatoz.com.

RELATED: Plants, Pollen and Allergies

Replacement options for a dying ash tree

September 30, 2020 • Leave a Comment

Ginkgos in the fall can be spectacular, the fan-shaped leaves glowing gold. Sometimes the color is a less showy yellow-green, but whatever the fall color, the leaves drop quickly soon after and all at once, a leaf raker’s dream.

Part 2 of 2 – Trees for root spaces greater than 10 feet wide

When an ash tree is the friendly cover above your patio or picnic table, and it is doomed to fall to the plague of emerald ash borer, its loss is a personal one. Here’s some consolation: in that location, with park-like room for roots to spread, many species can be expected to grow well and quickly.

Choose from this list and score one for diversity. By planting one of these excellent but underused species, you’ll help diminish the chance of whole-neighborhood defoliation during some future insect or disease attack.

Trees for root spaces at least 10 feet wide

These trees need larger boulevards and islands, where roots have at least 10 feet to spread in all directions:

Ginkgo (Ginkgo biloba, fruitless male varieties such as ‘Autumn Gold’ and ‘Santa Cruz’) 50 to 80’ tall with a variable spread (‘Santa Cruz’ is very wide, ‘Autumn Gold’ just a bit more than half as wide as tall). Grows 12” or more per year in its youth, slower as it matures. Flowers are inconspicuous. Fall color can be a superb gold. Female trees are not desirable as the fallen fruit is malodorous. Full sun. Prefers deep, moist, sandy soil but will tolerate almost any situation.

Hackberry (Celtis occidentalis) 40 to 60’ tall and wide, may be larger. Grows 1 to 2’ per year. Grows in almost any soil and moisture condition, in full sun. Makes no show of flower or fall color. Hard-seeded, berry-like fruit loved by birds and small mammals. This is another of many native trees that are just being discovered for use in the landscape. Like the ash, it’s a tree that rarely stars, yet always fills a supporting role. Some selections have been made, such as ‘Prairie Pride’ with especially lustrous leaves and a broad crown or ‘Windy City’ for a fast growth rate and especially wide spread reminiscent of its relative, the American elm.

Hardy rubber tree (Eucommia ulmoides) 40 to 60’ tall and wide. Grows 12 to 18” per year. Lustrous dark green foliage that’s pest free (and so it’s wonderful to sit under!). Inconspicuous bloom. No fall color. Full sun and almost any type and condition of soil. This tree fits the bill for people who want a non-fussy, relatively fast-growing, pest-free shade tree that does not drop fruit or seeds.

Turkish filbert (Corylus colurna) 40 to 50’ tall and about half as wide. Grows 12-18” per year. Nothing worth seeing in its tiny flowers or fall color. Nuts ripen in fall. Dark green foliage is pest free. In full sun and well-drained soil can tolerate almost any other adverse condition, including the droughty soils that cause scorch on maples.

**Yellowwood is a little known native that’s nearly pest free, a true showstopper in bloom or fall color, and excellent for shade on small properties by virtue of its wide spread.**

Yellowwood (Cladrastis kentukea) 30 to 50’ tall. Wider than tall. Grows about 12” per year. Fragrant white flowers in large pendant clusters in June. Smooth gray bark. Full sun and well-drained soil.

Trees that should not have any restriction to their roots

These are trees that belong in back yards, parks and wide open spaces.

**Bald cypress strikes many people as an evergreen, then surprises them in fall by dropping its needles.**

American linden (Tilia americana) 60 to 80’ tall and 2/3 as wide. Grows 12 to 18” per year. Small white flowers in June are fragrant enough to carry across a yard and very attractive to bees—thus this is called “bee tree.” Fall color sometimes yellow. Full sun to half sun. Almost any soil.

LEFT: American linden is a stately, dependable shade tree—pyramidal in its youth, showy in bloom, and comfortably rounded in old age. RIGHT: Bur oak has no showy flowers and its fall color is dull yellow. But it is rich in character with deeply ridged, corky bark—an outline to admire while you lie in its shade.

Bald cypress (Taxodium distichum) 50 to 70’ tall and half as wide. Pyramidal. Grows 1 to 2’ per year. Fern-like foliage emerges yellow green and fades to yellow or orange-brown before dropping in fall. Shaggy red-brown bark and buttressed trunk base are attractive. Full sun. Moist to wet soil.

Black gum is all you could want in a shade tree—high branched, not messy, and great fall color. However, it is not tolerant of compacted, dry or highly alkaline soils, so plant it to replace a back yard tree, not one by the street or sidewalk!

Black gum (Nyssa sylvatica) 30 to 50’ tall and 2/3 as wide. Grows 12” per year. Its bloom is inconspicuous but fall color is stupendous, from yellow orange to deepest scarlet. Small fruits ripen in early fall and are eaten by birds. Full sun or part shade. Deep, moist, well-drained soil. Don’t site it in harsh winds.

Bur oak (Quercus macrocarpa) 70 to 80’ tall and wide. Can be larger. 8 to 12” growth per year. Nothing to note in terms of flower or fall color. Full sun. Most any soil. More tolerant of city conditions than almost any other oak.

Dawn redwood (Metasequoia glyptostroboides) 70 to 100’ tall, 25’ wide. The tree is an impressive pyramidal form. Grows 3’ a year. Inconspicuous flower. Foliage is ferny, very attractive and sometimes red-orange in fall. Bark is shaggy red-brown, easy to like. Full sun. Prefers moist, well-drained soil but is very tolerant of wet soil. Pest problems are very rare.

LEFT: Dawn redwood may keep its lowest branches into old age and sweep the ground, or branches can be pruned to accommodate traffic. The author was not a believer until she saw dawn redwood as a magnificent street tree in Manhattan. RIGHT: Kentucky coffeetree in winter is a stately form indeed.

Kentucky coffeetree (Gymnocladus dioicus) 60 to 75’ tall, not as wide as tall. Can be larger. Grows about 12” per year. Flower is insignificant. Female trees can bear large, hard pods; if this is unacceptable, hold out for the male variety ‘Prairie Titan’ or ‘Stately Manor.’ Fall color may be a good yellow. It can aggravate fastidious rakers since in the fall the leaves, the ribs that connect the leaflets, and the seed pods drop at different times. Full sun. Deep, moist soils are best, but the tree will tolerate almost any city condition. This tree got its name when early American settlers used the seeds as a coffee substitute, but we are now told its seeds are toxic.

Lacebark elm is a dependable, fast-growing, wide-spreading shade tree with gorgeous bark. It has an additional common name, Chinese elm, that causes some people to confuse it with an inferior tree, Siberian elm.

Lacebark elm (Ulmus parvifolia) 40 to 50’ tall and wide. Grows 1 to 2’ per year. Inconspicuous flower. Fall color may be yellow or red-purple. Mottled, peeling bark is a plus in winter. Full sun. Moist, well-drained soil is best but it tolerates many soil conditions.

**Swamp white oaks are faster-growing than most people realize, so we can enjoy them in their youth as well as leave them to our grandchildren.**

Sawtooth oak (Quercus acutissima) 40 to 60’ tall and wide. Grows 2’ per year during its first twenty years. Golden catkin flowers in spring can be attractive. Foliage is very clean, deep green in summer, often a good yellow in fall. Acorns drop early in fall. An impressive, high-branched shade tree. Full sun. Well-drained soil.

**Shingle oaks can frustrate some gardeners by holding onto leaves through winter. Others see the leaves as winter interest. Isn’t diversity grand!**

Shingle oak (Quercus imbricaria) 50 to 60’ tall and wide. Can be larger. Grows 12 to 18” per year. Leaves unfurl red, are lustrous dark green in summer and become yellow to red-brown in fall. Full sun. Moist, well-drained soil.

Swamp white oak (Quercus bicolor) 50 to 60’ tall and wide. Can be larger. Grows about 12″ per year. With age, develops an impressive, stout trunk and deeply furrowed bark. Fall color can range from yellow to maroon. Full sun. Moist to wet soil.

Article by Janet Macunovich and photos by Steven Nikkila, www.gardenatoz.com.

Replacement options for a dying ash tree

September 1, 2020 • 2 Comments

Part 1 of 2 – Ash replacement trees for root spaces less than 10 feet wide

Chinese fringetree is a workhorse that also blooms once a year and supplies fruit for the birds. Remember, the ash trees we’re replacing offered no flower and only brief yellow fall color. Their greatest quality was dependable growth even in tough places.

Emerald ash borer has erased millions of native ash trees from our landscapes and forests. It’s hard to believe that similar devastation happened just decades ago, when millions of American elms fell to Dutch elm disease, or that America has also experienced the loss of certain poplars, black locusts and virtually all of its millions of acres of American chestnuts since 1850.

Perhaps we can stop history from repeating itself. After every previous loss, we planted as America always has—in a big way, in masses. As a result, our urban forest is dominated by just a few species, notably various maples, honeylocusts and littleleaf lindens. To protect ourselves from future widespread loss we have to break that pattern and plant a greater diversity of trees around our homes and on our waysides.

Even before the onset of emerald ash borer, concerned arborists had put a moratorium on ash and maple planting and begun planting less common trees. Tree planting became a matter of mixing species within a city block, rather than planting lines of hundreds of the same species, even the same clone of a species. They are making sure that trees won’t in the future be exposed and lost in blocks of hundreds and thousands, as they are now being lost.

For that next epidemic will occur. In this age where materials are whisked from one side of the world to another, complete plant quarantine and protection from new pests is impossible. You can take the same smart step and plant one of many wonderful tree species that are not in the “big three” when you replace that lost ash.

Choose from the following line-up. It’s a catalog sorted by the amount of root space the tree will have to grow in. After looking into all of them, I have an interest in so many that where my family removed 20 dying ashes from a relative’s property, we’ll probably replant with 20 different species from this list!

Trees for spaces where roots can spread just 5 feet wide

These trees can tolerate the restricted root space of small islands and the narrowest strips between sidewalk and street. Some may need pruning to remove lower branches as they grow, creating clearance for traffic below the main branches.

Chinese fringetree (Chionanthus retusus). 15-25’ tall, may be taller. Slow to grow, less than 12” per year. Often shrubby in habit, to attain tree form must have lower limbs removed as it grows. Hardy within the Detroit Metro area but may not be hardy in the colder parts of zone 5 in suburbs. Bright white confetti flowers in June. Blue-black fruit in fall is relished by birds but borne only on female trees, if a male fringetree is nearby. Fall color may be yellow. Grows in full sun or part shade. Prefers deep, moist soil but is very tolerant of a wide range of soil conditions.

Crabapples such as ‘Sugar Tyme’ are most often listed with ornamental trees, but those between two and three stories tall serve well as shade trees. It may be necessary to remove lower limbs while the tree is young to provide clearance for pedestrians and other traffic.

Crabapples (Malus varieties with known disease resistance such as ‘Adams,’ ‘Prairifire,’ ‘Red Jewel,’ and ‘Sugar Tyme’). 15’ (‘Red Jewel’), 18’ (‘Sugar Tyme’), 20’ (‘Prairifire’), 24’ (‘Adams’), rounded or slightly narrower than tall. Grows about 12” per year. Flowers white (‘Red Jewel’), pale pink (‘Adams’, ‘Sugar Tyme’) or dark red-purple (‘Prairifire’). Fruit small, red and persisting prettily into and even through winter. Birds eat the fruit in late winter. Full sun, well-drained soil.

Hawthorns are game for drier, windier places than many trees and their fruit is a favorite for songbirds. For safety’s sake around your home, choose a thornless variety such as ‘Crusader’ or the nearly-thornless ‘Princeton Sentry.’

Hawthorns (thornless types such as Crataegus phaenopyrum ‘Princeton Sentry,’ Washington hawthorn, and C. crusgalli var. inermis, Crusader hawthorn). 20 to 25’ tall and wide. 12-15” growth per year. White flowers (with unpleasant odor—Crusader) come later than crabapples but help these trees masquerade as crabs. Fall color orange to red or purple. Crusader keeps its small reddish fruit into early winter, ‘Princeton Sentry’ until spring; birds are attracted to both. Full sun and any type of soil so long as it is well-drained.

**Japanese tree lilacs are most often single-trunked, like this young one that will thus be very good one day as a small shade tree.**

Japanese tree lilac (Syringa reticulata). 20 to 30’ tall and not quite as wide. Grows 12 to 18” per year. Creamy white, fragrant flowers open in June, weeks after common lilac. No significant fall color but the polished red brown bark brightens a winter day. Full sun. Well-drained soil.

Kousa dogwood has a reputation as “the dogwood for the sun” but this is misleading. Although more tolerant of full sun than its cousin, the earlier blooming flowering dogwood (*Cornus florida*), it prefers some shade. In the sun, it’s known for developing drooping leaves and failing to attain the much-sought horizontal branching.

Kousa dogwood (Cornus kousa). About 20’ tall and wide, can be larger. Grows about 12” per year. Often sold as a multi-stemmed or very low-branched specimen, but single trunk kousa dogwoods make excellent small shade trees if lower limbs are discouraged or removed. White flowers in June that persist into July. Varieties with pink flowers, larger or later blooms are available. Large rosy fruits favored by birds in late summer. Bark develops polished tricolor effect as the tree ages, very attractive in winter. Fall color may be good maroon. Part shade is best but will tolerate full sun. Moist, well-drained soil.

Redbud. Who would have thought that the romantic woodland tree that blooms in early May as if flocked with thousands of red-violet flowers would be such a winner in parkstrips along roads and driveways. Needs pruning while young to remove lower limbs for pedestrian and vehicular traffic.

Redbud (Cercis canadensis). 20 to 30’ tall and wide. Very fast growth when young, slowing to 12 to 18” per year. Flowers are tiny but numerous, red-violet nubs all along the branches in May. Fall color can be a clear yellow. Bark is near-black with crevices revealing orange beneath. Some people object to the shaggy winter look in a year when many seed pods form. Best in half sun or full sun in moist, well-drained soil but is very tolerant of almost all light and soil conditions except soggy soils.

Serviceberry is a native with international appeal. You can buy named varieties such as ‘Autumn Brilliance,’ ‘Cumulus,’ ‘Prince Charles’ and ‘Snowcloud,’ which have been selected by growers in Europe and the U.S. for traits such as tight upright form, larger flowers, more consistent fall color or resistance to the few leaf diseases that may harry this tree.

Serviceberry (Amelanchier species). 25’ tall, may be taller; 15-20’ wide. Grows 1-2’ per year. Fragrant white flowers in early May. Edible, sweet, blueberry-sized fruit in midsummer loved by birds. Fall color variable each year, yellow to deep red-orange. Smooth gray bark. Best in sun or half-sun in moist, well-drained soil.

Trees for root spaces between 5 and 10 feet wide:

**Amur cork tree assumes such an interesting broad shape and open crown that it invites you to come into its shade.**

Amur cork tree (Phellodendron amurense, fruitless varieties such as ‘Shademaster’ and ‘His Majesty’). 30 to 45’ tall, often broader than tall. Grows 12 to 18” per year. No showy bloom. Brief yellow fall color. Very open crown provides light shade and beauty of line in winter. Handsome corky bark develops in its old age. Full sun. Most soils are okay.

**Golden rain tree provides welcome showy bloom in mid- or even late summer but is not well-known, so it has not been widely planted.**

Golden rain tree (Koelreuteria paniculata). 30 to 40’ tall and wide. Grows 1 to 2’ per year to form a round crown of widely spaced branches for light shade. Flowers are large yellow conical clusters in late June, but bloom time is variable from plant to plant; some don’t flower until August. Seed pods are showy, like yellow-green Chinese lanterns draping the tree in bunches. No fall color. Full sun to part sun. Any well-drained soil. Tolerates high alkaline soils, drought and heat.

Hophornbeam or ironwood (Ostrya virginiana). 25 to 40’ tall and wide. Grows 8 to 12” per year. No significant flower or fall color, just a dependable small shade tree. Full sun to half shade. Well-drained soil.

**Hornbeams have lustrous foliage and sensuous bark. They also tend to hold their foliage long into the winter and so are often planted to serve as tall hedges.**

Hornbeam (Carpinus betulus, European; C. caroliniana, American). 40-60’ tall, 30-40’ wide. 8 to 12” growth per year. American hornbeam or musclewood smaller by half and slower to grow than European. Inconspicuous flower. Fall color late, yellow, variable by year. Smooth steel gray bark more or less fluted like a well-muscled, flexed biceps. Best in full sun and well-drained soil.

**Katsura foliage is captivating for its rich color in summer, lack of insect and disease damage, and the sound it makes in a wind.**

Katsura (Cercidiphyllum japonicum). 40’ tall, may be taller; variable in width. Blue-green foliage is purple while leafing out, yellow in fall. Grows 1-2’ per year. No significant flower or fruit. Best in rich, moist, well-drained soil in full sun.

**Mountain silverbell tends to be low-branched, so it may need pruning of lower limbs while young to obtain clearance for traffic in its shade.**

Mountain silverbell (Halesia monticola). 60’ tall by about 40’ wide, upright or conical in form. Grows 12-18” per year. White or pale pink bell flowers hang from the branches in May. Fall color is not usually notable. Part sun is best. Moist, well-drained soil.

Article and illustrations by Janet Macunovich and photos by Steven Nikkila, www.gardenatoz.com.

Janet’s Journal: Picking a size: Buy plants big or start them small?

May 2, 2020 • 3 Comments

Once, we felt fortunate to find the type of plant we wanted. Now, what was unusual is common and the problem is deciding which size to buy. How to choose between pots of varying sizes, divisions, cells or even balled and burlapped? Here’s some help.

Here we are at the garden center, wrestling once again with that essential question: When picking a size, is it better to pay more, for immediate satisfaction, by buying the largest specimen? Or is a smaller plant the wiser investment?

The answer is a classic: It depends. But current research is providing objective, specific and sometimes surprising information that may weigh in your decision.

While growing in the field, this river birch had a root mass in balance with its branch spread, 6 feet wide or more. Its garden center root ball may seem large and is certainly heavy, yet it’s not 6 feet but 2-1/2 feet across and contains just 5 to 18 percent of the fine roots the tree had in the field. (Estimate per Gary Watson, Morton Arboretum, in Extension bulletins issued by several Midwest States and in his book *Principles and Practices of Planting Trees and Shrubs*.)

General buying guideline: Roots rule and water pays the bills

No matter what plant you’re buying, choose the package that delivers more roots in a wider formation, and plan to water attentively until the plant resumes growing as well as it did in its production field.

All plant parts begin as soft growth—as leaf, shoot or root tip. 95 percent of that growth is water, which enters the equation as a puddle sinking into the soil, pushing into soft root tips and being drawn up by photosynthesis to the leafy part of the plant. The winner in any growing contest will be the plant with enough roots to serve its whole top, spread to cover a wider surface that “catches” a bigger puddle.

Roots develop only when leaves produce more sugar and starch—energy—than they need to sustain themselves and woody parts nearby. As the root system expands, more water can enter a plant, which can then support more leaves. So leaves and roots grow in balance, equal in mass and in width of spread.

These viburnum shrubs are being grown in the flat pan method, for minimal root loss at transplant time. They’re given a relatively shallow but very wide circle of loose soil in which to grow. At sale time, each is lifted with roots intact, weighing much less than if it had been dug to make a traditionally-configured root ball.

When a plant must be dug from one place to be planted in another, root loss is inevitable. When the plant is grown in a container that prevents roots from spreading as wide as the branches, it can’t make use of natural, wide puddles but becomes reliant on a near-constant flow of water through its small area of ground, via frequent watering or trickle irrigation.

It may be a year or more before a transplant’s leaves manufacture significant spare energy and roots begin to recoup their loss. As long as the roots remain “behind,” the plant will grow fewer new leaves each spring than it should. In such a year, total root growth can’t measure up to potential, either. A few or many years can pass during which the top remains the same size or even shrinks and the roots slowly increase, until balance and normal growth resumes.

If you have your choice in seedling trees, choose the largest root collar diameter—girth at the base of the stem. This measure is regarded by producers of seedlings for reforestation as the best single predictor of the tree’s survival and growth in the field.

Trees: Smaller is often better

When instant gratification is an operative factor, you can’t persuade yourself or anyone else to buy small. But if you think putting a larger tree in the ground is a jump start toward a shaded yard or the glory of a full-sized ornamental tree, think again. Small trees often catch up to larger trees planted at the same time and may keep growing faster for decades.

Tree roots grow out, not down. So to stay balanced in mass and spread with the top, they spread wider than the branches. Even small trees have wide root systems. If a conventional pot or root ball was cut wide enough to encompass all of a substantial tree’s roots, it would be an unmanageable package for grower, garden center employee and you. Thus all trees sold at a garden center are unbalanced with the possible exception of bare root trees, seedlings or “whips,” and those grown in the unfortunately-uncommon flat-pan method.

The larger the top of the tree, the more out of balance its for-sale root ball. So the largest trees take the longest to regain balance and resume growth.

We buy trees rated according to their trunk diameter: “one-inch caliper,” “two-inch caliper,” etc. Studies show there is a direct relationship between this trunk size and root re-establishment time. For every inch in trunk diameter, a properly-sited, well-watered tree will take at least one year and possibly longer to recoup its losses. Smaller trees recover faster than larger trees—one year for a one-inch tree, five years or more for a four-inch tree.

That means a one-inch tree may shake off its shock and resume growing roots at a normal rate even during its transplant year. For most tree species, it’s normal to lengthen each root about 18 inches during a typical, zone 4-5 growing season. With that much new root, the tree is able to produce leaves and extend its branches to full potential the following spring—18 inches or more for fast-growing species like silver maple or river birch, 12 to 18 inches for moderate growers such as red oak and katsura, and 6 to 12 inches for slow-growing American hornbeam or bur oak.

Meanwhile, a four-inch caliper tree will take five years to return to this norm. It may extend its roots and its branches only an inch or two in year one, and continue to creep in growth over the next four years.

Exception: In seedling trees, pick the largest

So where you want one or a few trees, the fastest possible growth, shortest term of critical care and healthiest trees in the long run, buy small rather than large.

However, if your aim is to replant a forest or start your own grove of trees, seedlings or unbranched young trees called “whips” are usually the way to go. In that case, bigger is better. Given a choice of many whips, choose those which are thickest at their stem base. If all have the same size stem base but some are taller, choose the taller.

Pacific Regeneration Technologies, a network of reforestation nurseries in Canada and the U.S., has compared survival and growth rates of smaller and larger seedlings in the field. Although there are many variables that can affect these plantings, PRT’s findings are persuasive—thicker and taller seedlings have higher survival and growth rates. In one study of Douglas fir, the differences in survival and height remained almost unchanged even 21 years after planting.

Shrubs: Hedging changes the bet

Shrubs and trees are the same in many ways, including best planting size. The wider the roots and the closer they are to being balanced with the top, the more quickly that shrub will “take” and the better its long-term prospects.

Shrubs to be used as hedging are exceptions. Smaller shrubs, even seedlings, almost always outgrow larger plants when planted in close rows. A hedge begun with smaller plants is ultimately fuller, healthier and requires less care. Even most important, the hedge grown from seedlings or small shrubs is less likely to suffer middle-of-the-row losses as it ages.

Competition for water is why large-plant hedges fall short in speed and fullness, compared to hedges begun with smaller plants. Larger plants have larger root balls and once planted, each one has proportionately less root-growing space.

When roots are in direct competition with other roots, they grow slowly, if at all. It makes no difference that competing roots are from a related plant and the two sets of roots, if growing vigorously, could graft and become a single system. A line of large plants with root balls tucked one against the next is a line of plants with only half its roots free to grow. At best, those plants can grow at half capacity.

In addition, smaller plants have been sheared fewer times, so they’re less dense and cast less shade on other plants’ bases. A hedge grown from whips becomes and remains full at the bottom. Larger shrubs, pruned repeatedly for fullness before being sold to the hedge planter, thin out at the base and rarely regain density as they grow together.

A hedge that began with crowded roots remains weak. The weakest individuals are in the center, where competition was most fierce, side roots atrophied and each plant’s root mass remained small. Years and even decades later the hedge crowded at planting is most likely to be affected by drought, severe winters or seasons of high insect or disease occurrence. The plant in that hedge most likely to die is one in the middle.

Every perennial is divisible. Making one from many gives each division a faster start and better long-term outlook. The peony division on the right could grow roots freely from only one side when snugged up to its sister shoots. Separated, it can grow to all sides. Within the mother clump, it might have initiated two shoots, and stored energy to make four the next year. Alone, it might form three or four shoots this year and create enough stored energy to break ground with five or six stems next spring.

Perennials: Buy what you can afford, but give them rooting space

Trees, shrubs, vines and bulbs are perennials, as are those plants in the group most commonly called perennial—herbaceous flowering species from anemone to zebra grass. I hope you’ll keep in mind that every perennial is alike in a way that should influence your choice in plant size. That is, they all store energy this year for next year’s growth.

So buy perennials for the roots. Select the biggest, widest root system.

Avoid root-bound plants of any kind. Plants absorb most water and grow new roots primarily from root tips. Since this plant’s roots turned at pot edge and grew down, all of those tips are now crowded at the bottom, a very small area, but now it’s all the plant has from which to draw water. Since roots will drain that spot more quickly than water from surrounding soil can move in, the plant may dry out even if the soil around the root ball is moist. Also, new roots erupting from that tiny spot will each be in close competition with the others. The process of expanding its root system will be slow. (Although it’s a setback to the plant, my best bet is to cut the roots to create new root ends in more areas.)

As far as the roots spread by the fall of one year, that’s as much area as the plant’s top will cover the following year. So do everything you can to encourage roots to spread during their first year.

If you buy perennials of any type for immediate impact, you will probably also plant them close together. That’s fine, if this year’s show is all that counts. However, to make the most of those plants over the long run, understand that crowded roots won’t grow as much this year as they could, so next year’s top growth will be less and plants will be weaker overall. If you must crowd for immediate show, enjoy the display then dig and replant the component parts farther apart.

To cover the most ground for the least money, buy smaller perennials. (But not too small—see the notes about annuals and vegetables, below.) If the plant you want is available only in large pots, buy those and divide them as you plant.

Annuals and vegetables: Pay-off’s in the larger cell

For healthy, lush annuals and vegetables, space them as directed. That is, if the pot tag says “space plants 12 inches apart,” give every one its own square foot. A flat of 48 plants can cover 48 square feet—a 4-foot by 12-foot bed.

Want a more spectacular show, sooner? Do what botanical gardens do—keep the spacing the same but start with bigger plants. The higher cost per square foot pays off in immediate display.

Since most studies are on vegetables, we need to apply that data to annuals—there are enough parallels to make the comparison worthwhile. For instance, vegetables that flower earlier go to market sooner. Those that are healthier bear larger fruit and have fewer pests, so more of the fruit is cosmetically perfect and sells for a higher price. We value early flowering and health in bedding plants, too.

Trials run in Michigan, Kentucky, Missouri, Georgia and Minnesota on tomatoes, broccoli, cabbage, pepper and watermelon planted from various size cells, showed that the largest transplants yielded earlier and/or more. From larger sets the first picking of tomatoes and peppers was up to twice as great. The broccoli crop was 25 percent more, cabbages 16 percent heavier and watermelon harvest 7 percent higher. We flower growers may not be big on math, but we can still see that sometimes it can be worth spending 50 percent more for the chance at doubling the show!

Parting shot: Small plants more foolproof

Still not sure what to do? In such cases, I buy small. It pays off, especially when I’m not sure what the plant can do or where it will grow best.

Big, bushy plants can fool me by looking big and bushy even as they lose ground—who notices ten leaves gone when there were 200 to start?

A plant that comes to me with just ten leaves tells me clearly, week by week, how things are going. If it’s thriving, its leaf count increases and the new foliage matches the old in size and color. If it begins to lose ground, that’s also quickly apparent. If it seems a move is in order to correct the situation, that’s simpler with a small plant too!

Article and illustrations by Janet Macunovich and photos by Steven Nikkila, www.gardenatoz.com.

ALSO… How Much are the trees in your yard worth?

ELSEWHERE: Planting a tree successfully requires the correct planting depth

Digital Editions

Archive for the Janet’s Journal department

These handy lists will help you select excellent shrubs and place them in the right spots

Big, multi-season beauties

Big, with one main show

Satisfactorily small and multi-talented

Evergreens

Assurance #1: The bees will be there—on time, every time

Assurance #2: Bugs will get ahead of you

Assurance #3: Dead wood will fool the unsuspecting eye

Assurance #4: Slow starters will start when you give up

Assurance #5: You’ll estimate wrong about the mulch you need

Assurance #6: The weather will conspire against you

Assurance #7: Blue and pink hydrangeas will disappoint you

Final reassurance: Revelation will come

Bulbs come up too early

Bloom one year, never again

The stems flop over before the plants bloom

Leaves emerge fine but quickly discolor and die

Failure to exit gracefully

What can I plant for the most color and lowest maintenance?

Matching plant and site

What are some fast-growing trees? We need shade!

Shade trees that grow quickly

How can I make my doorway look (better, more inviting, classier, more colorful, etc.)?

Making great combinations in the landscape

What can I plant that grows quick, for privacy?

What can I plant to soften the corner of the house?

What should I plant in the space between the house and the front walk?

Long-interest, front-walk perennials

How can I hide the (utility box, air conditioning unit, trash cans, well head, etc.)?

What can I plant along the edge of the deck/patio?

Where can I get the cheapest plants?

How to help your plants make it through the frosty weeks of April

Moist soil makes a warm night.

Everything’s warmer under a tent.

Fiber makes a great frost blanket.

It’s a cloche call.

Gracious sakes, come in outta that wind.

Cover those feet.

What gardeners do best: Improvise.

Dream of ideal plants and places.

Think “grocery produce section” when selecting bulbs

Include early-, mid- and late-blooming types

Plant them where you’ll see them

Plant them deep

Parade of bloomin’ bulbs

Select the right plants to reduce allergies in the garden

Spot allergy offenders before they’re under your nose

Wind-pollinated means trouble

Trees, grasses and weeds most to blame for allergies

Spotting and reducing non-plant allergens

Replace troublemakers with low-allergen plants and materials

Design more dramatically, and build in filters

Reduce your work to reduce your exposure

Work smart when you spend time in the garden

Most common culprits in pollen allergies

Recognizing wind-, insect- and bird-pollinated flowers

Battle of the sexes

Part 2 of 2 – Trees for root spaces greater than 10 feet wide

Trees for root spaces at least 10 feet wide

Trees that should not have any restriction to their roots

Part 1 of 2 – Ash replacement trees for root spaces less than 10 feet wide

Trees for spaces where roots can spread just 5 feet wide

Trees for root spaces between 5 and 10 feet wide:

General buying guideline: Roots rule and water pays the bills

Trees: Smaller is often better

Exception: In seedling trees, pick the largest

Shrubs: Hedging changes the bet

Perennials: Buy what you can afford, but give them rooting space

Annuals and vegetables: Pay-off’s in the larger cell

Parting shot: Small plants more foolproof