Archive for the shrubs tag

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

Can rabbit manure be used as mulch around plants?

March 11, 2021 • Leave a Comment

We have a pet house rabbit that is litter trained. Can the manure and litter (made from recycled newsprint) be used as mulch in a perennial bed or around trees and shrubs?

This sounds like a gold mine since rabbits are vegetarians. But it comes with significant cautions. Rabbit manure is higher in nitrogen than even chicken manure. It also contains phosphorus. Nitrogen is great for leaf production. The phosphorus is good for fruit and flower production. So consider exactly what you will be enhancing with its application. Average N-P-K (nitrogen-phosphorus-potassium) analysis of composted rabbit manure is 2-1-0.8, which is relatively low compared to other commercial products. In order for the manure to be useful, it must be hot composted, preferably for a year, to reduce the probability of transmitting any pathogens lurking in the litter. A hot compost pile should measure at least 150 degrees in temperature.

Composting the litter changes the material into a form plants can better use. It also allows odors to dissipate. After the year-long composting, it should be applied to the soil in late fall and worked in. Preferably, it should not be used as mulch and never uncomposted, as the high level of nitrogen can actually burn and damage plants, even with the newsprint base. Since it has to be worked into the soil to be effective, you might find this easier with your perennial bed in fall than disturbing the roots of trees and shrubs.

What are some suggestions for deer-resistant plants?

December 15, 2018 • Leave a Comment

My subdivision has been taken over by deer. As I plan next year’s garden, please suggest some perennial flowers or shrubs that deer will not eat.

If deer are hungry enough, they eat just about anything. This answer will include deer-resistant or rarely-damaged varieties and resources to check out more. You might first consider deterring deer from entering your garden. One suggestion is a motion-sensitive sprinkler, called the ScareCrow, which is available at many garden centers. It sprays a shocking blast of water about twenty feet, scaring away deer. Move it periodically or the deer “learn” the pattern, but it is harmless and waters your plants. Be sure to turn it off if you have guests! Also, deer do not like prickly items, many fragrant plants, and footing areas that make noise or feel unstable.

Here are some plants that deer tend to avoid. Bulbs: allium, daffodil and autumn crocus. Herbs: dill, purple coneflower, lavender, sage, tansy, thyme. Shrubs: boxwood (Buxus sempervirens), American holly (Ilex opaca), and Japanese pieris (Pieris japonica). Trees: paper birch (Betula papyrifera) and Colorado blue spruce (Picea pungens). Perennials: yarrow, columbine, bergenia, bleeding heart, oriental poppy, Russian sage, coneflower (Rudbeckia), lambs’ ears (Stachys byzantina), and yucca. Groundcovers: sweet woodruff, dead nettle (Lamium maculatum), plumbago (Ceratostigma plumbaginoides), and pachysandra.

Deer-Resistant Plants for Homeowners is a 2008 publication by Michigan State University, Bulletin E-3042. Contact your county extension office for a copy (www.msue.msu.edu). Also try the book Deerproofing Your Yard & Garden by Rhonda Massingham Hart (Storey Publishing).

Flowering Shrubs: Colorful Characters

April 3, 2018 • 2 Comments

by Keith Alexander

“April showers bring May flowers”—we’ve all praised the coming of spring with this cheerful rhyme. After the cold, dreary days of winter, it’s here… Spring! This is a great time to plant shrubs so they can begin to establish themselves before the long, hot days ahead. It is best to plant flowering shrubs before they leaf out in the spring. That said, with the proper care and watering, they can be planted at any time. I have put together a list of some of my favorite shrubs. By no means exhaustive, this list is a great starting point for some colorful ideas.

‘William Penn’ Barberry
This dwarf, dense, semi-evergreen plant (Berberis x gladwynensis ‘William Penn’) will grow 4 feet tall and 4 feet wide over 5 or 6 years. In May, tiny, bright yellow flowers will cover the waxy bronze-green foliage that looks much like holly. In the fall, these 1- to 2-inch narrow leaves turn a beautiful bronze color and remain on until spring. In a mild winter, this zone 5/6 plant will bounce right back to bright green. If the winter was a tough one, sometimes the branches that were above the snow may die back to the snowline or the center of the plant. Though this barberry is sometimes hard to find in garden centers, it’s worth looking for. Remember to plant it in a sunny location out of the west winter wind. This plant will do well in almost any well-drained location.

‘Dark Knight’ Bluebeard
This summer-flowering shrub (Caryopteris x clandonensis ’Dark Knight’) enjoys a sunny location in almost any type of soil. Rich green foliage gives way to beautiful purple/blue flowers that begin in June and continue for almost a month. A compact bluebeard, it only grows to 2 or 3 feet tall. It is best to cut this deciduous shrub to the ground each spring for maximum beauty, form and flower. It is resistant to most pests and disease.

Variegated Rock Cotoneaster
This slow, diminutive garden plant (Cotoneaster horizontalis `Variegatus’) is a graceful addition to any landscape, particularly a small space or rock garden. Its tiny, 1/4-inch white and green leaves turn burgundy before dropping each fall. A delicate coating of tiny pink blooms turn into shiny red fruits in late summer. Grows in a partial shade to sun location. This colorful character grows to 24 inches in 5 to 6 years.

‘Miss Kim’ Dwarf Korean Lilac
This compact-growing lilac (Syringa patula ‘Miss Kim’) gets only 3 or 4 feet tall. A reliable lavender bloomer each May, this fragrant lilac needs a well-drained sunny location for best performance. Sometimes found as a dwarf tree or top-grafted form, this lilac makes an excellent accent feature. It has beautiful medium-sized leaves that turn to a burgundy tint in the fall.

‘Sensation’ Lilac
One of the most outstanding lilacs available, this French hybrid form (Syringa vulgaris ‘Sensation’) boasts showy purple/red florets edged in white each spring. An upright grower, following the tradition of most other French lilacs, it can grow up to 10 or 12 feet tall. This fragrant lilac should be used in a sunny location where it has room to grow.

‘Abbotswood’ Potentilla
The group of plants that include potentilla is a large one, and this can make choosing the right potentilla a difficult task. ‘Abbotswood’ (Potentilla fruticosa ’Abbotswood’) is one of the best white-flowering forms of potentilla. It grows 2 to 3 feet high, with delicate blue-green leaves. A generous covering of white blooms decorate this dense shrub each spring. If the plant is pruned after it blooms in spring, a second crop of blooms will be your reward. This hardy shrub looks for a sunny location in any type of soil or exposure.

‘Gold Star’ Potentilla
Of the yellow potentillas, this one (Potentilla fruticosa ’Gold Star’) has a lower habit and larger, showy yellow blooms than most. Its growth should stay under 24 inches. Yellow flowers 2 inches wide will cover the plant throughout the summer if the spent blooms are pruned off. Once again, a sunny location is best for this and all other potentillas.

‘Red Ace’ Potentilla
Growing in a dense mound to 30 inches, this summer bloomer (Potentilla fruticosa ’Red Ace’) is coated with unique flame red, 1-inch flowers that are pale yellow on the undersides of the petals. This re-bloomer will change flower color from flame red to yellow based the intensity of the heat and moisture conditions surrounding this zone 3 hardy grower.

‘Royal Purple’ Smoke Bush
This large shrub (Cotinus coggygria ’Royal Purple’) grows to 15 feet tall. Its intense purple leaves are nearly 4 inches across. A delicate frosting of yellow blooms covers this plant during early summer, giving way to pink/purple seed heads. These long-lasting airy clusters cover the tree for weeks, giving the impression of a cloud of smoke. Plant this fast grower in a sunny location that allows for room to spread. Best planted in well-drained soil out of direct winter winds.

‘Alpina’ Japanese Spirea
A very dense mounding shrub (Spiraea japonica ‘Alpina’), this zone 4 summer bloomer makes a great accent plant in today’s modern, low maintenance landscape. Delicate pink clusters of bloom will cover this plant all summer long. Although there are many different spireas to choose from, this one rates high as one of the best dwarf, green-leafed forms. Almost any sunny location will be great for this 18-inch tall plant.

Limemound Dwarf Spirea
This brightly-colored, mounding plant (Spirea x bumalda Limemound) makes a dramatic accent plant for any landscape. A good choice for massing, this 24-inch tall plant has delicate pink blooms on and off all summer long. The most dramatic color comes from its orange and lemon-yellow leaves in spring that turn to lime-green throughout the summer. It finishes out the season with beautiful auburn-red foliage in the fall. Hardy to zone 3, this sun-loving plant will tolerate almost any type of location.

‘Sunburst’ St. John’s Wort
This upright hardy shrub (Hypericum frondosum ’Sunburst’) makes a great border, accent, or hedge plant. Its dense habit, and dense blue-green 1/2-inch leaves make an excellent background for the profuse yellow blooms that cover the plant throughout the summer. A zone 4 rating makes this one a hardy choice for almost any sunny location.

Koreanspice Viburnum
A medium grower to 6 feet, this viburnum (Viburnum carlesii) is one of the most fragrant available. Leathery green, 3-inch leaves are soon followed by 4- to 5-inch snowballs of pink/white fragrant blooms each spring. Following the blooms, small red fruits hold on until they turn black in the fall. These black berries are highly desired by the most discriminating of our feathered friends. This classic plant will do well in partial shade or full sun, and is hardy in almost any location.

Click to download a chart describing all the attributes of the flowering shrubs featured in this article. — Click on the image to download a chart describing all the attributes of the flowering shrubs featured in this article.

‘Pink Dawn’ Viburnum
Large, dark green foliage covers this upright grower (Viburnum x bodnantense ‘Pink Dawn’) to 8 or 10 feet. Very unique rose-colored blooms may open as early as February if the weather is mild. Its blooms are fragrant and hardy. Small, dark blue fruits will form in late spring. These small unobtrusive fruits make great attractions for the birds.

‘Shasta’ Viburnum
‘Shasta’ (Viburnum plicatum f. tomentosum ‘Shasta’) is an improvement on the traditional Japanese snowball viburnum. It has a compact habit that grows only to 6 or 8 feet. Showy white blooms coat the horizontal arching limbs, creating a dramatic effect in May. Its large, 5-inch leathery green leaves turn to a reddish purple color in the fall. The red fruits turn to black before the birds begin to feed. ‘Shasta’ makes a great border or screening plant in almost any type of location from medium shade to full sun.

Janet’s Journal: Usual Plants, Unusually Grown

April 27, 2016 • 4 Comments

Part 2 of 2

Shrubs grown as perennials and perennials grown as shrubs

This shrub, golden elderberry (Sambucus nigra ‘Aurea’), is cut back to leave just one or two feet of its two main trunks every spring. The result is a compact, golden “perennial.” — This shrub, golden elderberry (*Sambucus nigra ‘Aurea’*), is cut back to leave just one or two feet of its two main trunks every spring. The result is a compact, golden “perennial.”

Shrubs as perennials

Dwarf spireas can be treated like herbaceous perennials. Cut back to the ground early each April, they still bloom that summer, although a bit later than otherwise. Cut hard in this way, they are also often denser, a bit shorter, and the foliage color may be more intense.

If we grow a shrub for its foliage (barberry, privet, smoke tree and others), or we like the flowers and they are produced on wood that grew just this year (rose of Sharon, beautyberry, potentilla and others), why not cut it back to stubs every April 1, treating it like the herbaceous perennials we leave standing for winter interest? That’s what we can do with all of those on this list. Some of them you already grow this way (butterfly bush, blue mist spirea, Russian sage), and don’t even give much thought to the fact that they’re shrubs. The others on the list are just as amenable to this treatment.

What can you expect will be different about a shrub treated as a perennial? Cut back to nubs every spring, a shrub may be only 2 to 4 feet tall at its height every year—shorter than otherwise, but tall enough for most gardens. Flowering isn’t usually affected except that it may come later in the season than on un-cut shrubs of the same type—not a problem if you added these plants to your garden specifically to continue the floral show after spring and early summer perennials finish their show. The foliage on first-year branches is often larger and more intensely colored than normal, which is a plus. Also, the new wood itself is often more intensely colored than older branches, so shrubs we like for their stem color in winter are even more attractive when treated this way.

Shrubs grown as perennials:

Barberry* (Berberis thunbergii varieties)
Beautyberry# (Callicarpa japonica). Purple berries in fall are the attraction.
Blue mist spirea or bluebeard#* (Caryopteris x clandonensis)
Butterfly bush# (Buddleia davidii)
Chaste tree# (Vitex negundo)
Dwarf spirea#* (Spiraea x bumalda)
Elderberry* (Sambucus varieties with gold or bicolor leaf)
Golden vicary privet* (Ligustrum x vicaryii)
Panicle hydrangea# (H. paniculata) and snowball hydrangea# (H. arborescens). Please don’t confuse these with other types of hydrangea such as the blue-, pink-flowered or oak leaf types which need two-year-old wood to bloom.
Potentilla# (P. fruticosa)
Redtwig and yellowtwig dogwood (Cornus alba, C. sericea). Winter stem color is the primary show.
Rose of Sharon# (Hibiscus syriacus)
Smoke tree* (Cotinus coggygria)

* shrub grown for its foliage
# shrub grown for its flowers (on new wood)

Perennials as shrubs

Some herbaceous perennials are so large and sturdy that they can overwhelm the rest of a garden. Instead of shrubs, they can be used as hedges, specimens, or even foundation plants. The only catch is that they will vacate their spots once a year, either from fall when they die back until early summer when they’ve once again reached the desired height, or if their stems are sturdy enough to stand over winter, we lose them only from early spring when we cut them back until early summer.

One additional feature I require of perennials used this way is that they be long-lived and clump-forming. I want to be able to depend on them to be in the exact same place for a number of years, as I would a shrub.

Perennials grown as shrubs…

Boltonia (B. asteroides). 3 to 4 feet tall. White or pink flowers appear almost as a surprise every September.
Cup plant (Silphium perfoliatum). 6 feet or more. Produces small sunflowers in July.
False indigo (Baptisia australis). 3 to 4 feet tall. Contributes wands of blue flowers every June and can look like a black iron sculpture over winter.
Goatsbeard (Aruncus dioicus). 4 to 5 feet tall.
Ornamental grasses, particularly maiden grass (Miscanthus varieties) and feather reed grass (Calamagrostis acutiflora). Heights range from 2 to 8 feet. Fall and winter aspects can be stunning.
Peony. 3 feet. Hardly bears listing, since it’s almost a usual thing to grow it as a hedge.
Perennial sunflower (Helianthus x multiflorus). Cheery single or double sunflowers several inches across, every August. 3 to 5 feet tall.
Purple bush clover (Lespedeza thunbergii). 5 feet tall, with great showers of pink flowers every September.
Russian sage (Perovskia atriplicifolia). 3 to 4 feet tall.
Sedum ‘Autumn Joy’. 18 to 24 inches. Like peony, it hardly bears listing since it’s been in foundation plantings for decades.

Vines as shrubs, trees or groundcover

Climbing hydrangea (H. anomala petiolaris) is a very large vine but can be kept pruned to forms that range from shrubby to tree-form espalier. — Climbing hydrangea (*H. anomala petiolaris*) is a very large vine but can be kept pruned to forms that range from shrubby to tree-form espalier.

We think of vines when we need to cover a trellis or other vertical surface, but many vines are also happy to cover the ground. English ivy may come to mind right away, but keep an open mind to Hall’s honeysuckle (Lonicera japonica ‘Halliana’) and clematis that can be cut back in spring but still bloom that year (late-blooming species such as C. texensis and C. viticella and fall-blooming clematis C. maximowicziana, C. paniculata or C. terniflora).

If I want a vine to cover the ground and provide flower, too, there are some plants I have to strike off my list. Climbing hydrangea (H. anomala petiolaris), wisteria and trumpet vine (Campsis radicans) will clamber happily on the ground but won’t bloom there. Their flowers come after the plant has established a strong vertical framework with permanent (woody) horizontal side branches.

Some vines can also be convinced with regular pruning to stay in a relatively tight shape like a mounded shrub. With staking, they can even be a small tree. Evergreen euonymus (E. fortunei varieties such as ‘Ivory Jade,’ ‘Emerald Gaiety’ and ‘Sunspot’) is so amenable to use as a shrub that many people don’t even know how beautifully it climbs when given a chance.

A few, such as wisteria, trumpet vine, silver lace vine (Polygonum aubertii), evergreen euonymus and climbing hydrangea, can develop main canes so thick that they can serve as trunks. Strap a sturdy young cane to a strong post, cut off all suckers from the roots and shoots from low on the trunk-to-be, and give it a few years to thicken that cane. Don’t forget, though, that most of these are large plants and so their “crown”—once they’re trained as a tree—will need hard pruning at least once a year to keep it in bounds. Some, such as trumpet vine and wisteria, will also sucker like a wild thing, so it’s wise to site them where they will be surrounded by mowed lawn.

When is the best time to prune trees and shrubs?

May 28, 2011 •

by Steve Turner

I am often asked when is the best time and what should be pruned. The ideal time is when the tree is dormant, which is late fall to early spring. Since the tree is not active, the removal of limbs will be less stressful to the plant. It is also easier to see the structure of the tree without its leaves to better find problem areas like rubbing branches, weak crotches, cracked or broken limbs and competing leader branches. The tree will have more time to seal the wounds before the growing season starts and there will be less sap running from the wounds. Also, insect and disease organisms are not active at this time, so it reduces the risk of infection or pest infestation, which is why birches and American elms should only be pruned in the winter. The worst time to prune trees is late spring and early summer when their leaves are expanding and the tree is putting its energy toward growth.

A common myth is that large, mature trees can tolerate more pruning than small trees. In fact, the opposite is true. Only the outside inch or two of a tree is alive; the rest is made up of dead cells whose main function is to support the tree. That’s why a tree can be hollow but still be perfectly healthy. If you compare the percentage of live cells to dead cells between a small tree and mature tree, the difference is huge. A young tree might be made up of 90 to 100 percent live cells, while an old, mature tree might only have 10 percent or less. As you can imagine, the younger tree has a better chance to adjust to change.

A good rule for mature trees is that less is better. Try to avoid removing large limbs over 6 inches in diameter because it will be difficult for the tree to close the wound before decay sets in. Other options are cabling or thinning these large limbs as opposed to removing them. Good maintenance items for mature trees are removing deadwood and hazard limbs and thinning for weight reduction when necessary.

Young trees up to 8 to 12 inches in diameter need to be pruned properly for structure while they are still young to avoid the need to remove large limbs in the future. When pruning trees, keep in mind that the leaves produce the energy for the plant and that removing too much leaf surface from a tree or limb will starve the plant, causing die back or heavy sucker growth from that part of the tree.

“Topping” trees destroys them. They will never grow back to their natural shape and every branch that grows out of that wound area will be an accident waiting to happen. As the new limbs grow bigger and the rot in the wound increases, the branch will eventually break. A topped tree soon becomes a maintenance headache, with constant storm damage due to the weak branch attachment. If a tree is too large for its location, consider having it removed and replanted with a smaller species rather than topping it.

It is important to know what a tree’s natural shape will be when it matures before you prune it. For example, I see many weeping cherries that are pruned into a ball shape because all of the upright limbs were removed as they grew out of the top. If allowed to continue growing, these limbs would have eventually bent back down, creating the weeping effect that gives the tree its unique look. So it pays to do a little homework and find out what the tree’s natural shape is and help it reach its full potential. Not all ornamental trees need to be pruned into the traditional lollipop shape!

When it comes to shrubs, prune flowering shrubs soon after they are done blooming. Non-flowering shrubs and evergreens can be pruned as necessary to achieve a desired shape. Keep in mind that wider at the bottom is better than narrow — if you allow more sun to reach the bottom of the shrub, the plant won’t thin out as much. Avoid heavy, late summer pruning; too much pruning at this time will encourage new growth that may not harden off in time for winter. For those plants that don’t tolerate shearing well, like red or green twig dogwoods, it is best to prune them back to the ground when they become too large or sparse, and let them start over again by growing new limbs from the base.

Steve Turner, Certified Arborist, is from Arboricultural Services in Fenton, MI.

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