jhofley, Author at Michigan Gardener

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After 27 years, nearly 200 issues published, and millions of copies printed, we have decided it is time to end the publication of our Print Magazine and E-Newsletter.

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.

Plant Focus: Crocus

September 1, 2020 • Leave a Comment

For a gardener, there are few sights as welcome as the first crocus of the year, peeking its flowers through the freshly melted snow of late winter. Crocus is a very hardy perennial and one of the few plants that can bloom as early as February or March. By being hidden deep in the soil, crocus corms are naturally insulated from severe temperature changes, ice and wind. Flowering is initiated by just a few consecutive days of temperatures above freezing. Once the first few inches of soil can thaw, flowers emerge and will last for several weeks despite more wintry weather. Crocus flowers can protect themselves by closing up in the evening and also whenever they experience severe weather.

**‘Yellow Mammoth’ (Photo: Dutch Gardens)**

Crocus have long been popular with gardeners for several reasons. Their durable flowers are available in many colors including yellow, white, purple, blue, and pink. One plant will usually return year after year and develop offspring that can produce additional flowers in beautiful drifts. The two-inch flowers are made up of 6 oval petals that surround 3 prominent yellow to orange stamens. Crocus grow from one-inch corms rather than actual “bulbs.” Both are just compressed stems: bulbs consisting of fleshy scales and corms being more solid. Gladiolus is another example of a corm.

**‘Whitewell Purple’ (Photo: John Scheepers, Inc.)**

Crocus are native to the rocky slopes of the Mediterranean countries and southwest Asia. They adapt to cold winters, full or partial sun, and well-drained soil. Most Michigan gardeners have the first two, but well-drained soil may have to be created if clay is prevalent. Drainage can be improved by adding aged pine bark or compost to your soil. Since crocus corms are planted 3 to 4 inches deep, only about 4 inches of soil below them needs to be well-cultivated. Corms should be at least 3 inches apart. However, this is the type of bulb that looks great planted in more natural and random masses.

Most crocus have only one serious threat to their perennial existence. Hungry bunnies seem especially tempted by the leaves, flowers and corms of several species. Corms can be protected by several methods. Gravel worked into the soil above the corms will make digging them up difficult. Liquid or powder deterrents can be used to treat corms before planting. Keep in mind that freshly planted bulbs and corms are most likely to create curiosity amongst browsers. Once established, they are rarely disturbed. If all else fails, you can plant in below-grade, wire mesh cages that are impenetrable. To protect leaves and flowers, apply a granular deterrent or a spray.

**‘Ruby Giant’ (Photo: John Scheepers, Inc.)**

There are many varieties of spring-blooming crocus but most of the hardy ones fall into four species. Crocus ancyrensis is golden bunch crocus. The selection ‘Golden Bunch’ produces up to five deep orange-yellow flowers in a “bunch” per corm. Of the four species, this is one of the earliest to bloom; late February is not unusual if Mother Nature is cooperating. This is also one of the more vulnerable to attack from the bunnies.

**‘Jeanne d’Arc’ (Photo: John Scheepers, Inc.)**

Crocus chrysanthus is available in several varieties, all of which are referred to as snow crocus or golden crocus. ‘Cream Beauty’ is a strong grower that is primarily white with a white center. ‘Ladykiller’ is also white but with purple on the outside of the petals. ‘Advance’ is yellow inside but the outside is unique because the petals alternate creamy yellow and purple. Corms produce 1 to 4 flowers each in late February or early March. Like C. ancyrensis above, rabbits admire this species.

Crocus tommasinianus is a wonderful choice for several reasons. This species is the most pest-resistant crocus available. If you have lost crocus to rabbits or squirrels, this may be the choice for you. C. tommasinianus is also the most prolific grower. It will quickly naturalize to form masses of flowers. The most readily available variety is ‘Barr’s Purple.’ Its deep violet petals fade to a bright white center that is highlighted by bright orange stamens. It blooms almost as early as the above two species, usually in early March.

The most popular species is Crocus vernus or Dutch crocus. Unlike the previous species, one large flower with large gold stamens is produced from each corm. It is available in several colors ranging from white to stripes to purples. ‘Jeanne d’Arc’ is a bright white with large flowers. ‘Pickwick’ has large white flowers with dark lavender stripes inside and out. ‘Remembrance’ and ‘Flower Record’ are deep lavender and pale lavender respectively. Dutch crocus usually bloom from March to early April.

Fall is a perfect season for planting. Cooler weather means less heat stress for both plants and people. Plants are naturally becoming dormant and are far less susceptible to drying out and experiencing transplant shock. Fall is also the only season for planting spring-blooming bulbs and corms. Once the ground freezes, the opportunity is lost and you’ll regret not having these heralds of spring glowing in your early season garden. Crocus are relatively inexpensive and are available almost anywhere bulbs are sold. With minimal effort this fall, you can enhance your existing landscape and welcome spring with the bright blossoms of crocus.

**‘Blue Pearl’ (Photo: Van Bourgondien)**

Crocus CRO-kus
Plant type: Corm (commonly referred to as a “bulb”)
Plant size: 3-5 inches tall
Habit: Clump-forming
Flower colors: Purple, violet, reddish- purple, lilac, yellow, cream, white
Flower size: 2 inches wide
Bloom period: Late winter to early spring
Light: Full to partial sun
Soil: Well-drained
Uses: Plant in natural drifts in the perennial border, lawn or rock garden
Remarks: The corms develop offspring that can produce additional flowers to create a naturalized look

George Papadelis is the owner of Telly’s Greenhouse in Troy and Shelby Township, MI.

RELATED: Colchicum and Fall Crocus

ELSEWHERE: More on Crocus at Chicago Botanic Garden

State of Michigan seeks help finding disease-resistant survivor elms

August 3, 2020 • Leave a Comment

A century ago, elegant, vase-shaped American elms shaded neighborhoods with their lacy, arched canopies. Today, many of those trees are dead, skeletal husks—a legacy of the destructive Dutch elm disease. The fungal disease, spread by bark beetles, slowly wiped out most American elms after being introduced in the early 1900s.

However, the American elm’s story isn’t over. Midwest forest health experts are working to stage a comeback, and they need your help. Have you noticed any large, healthy American elms in your area or when out hiking in the forest? Those “survivor elms” might be tolerant of Dutch elm disease. If you are in Michigan’s colder climate zones (zone 5 and colder), you especially are encouraged to report these trees. Currently, there are no Upper Peninsula reports and very few northern lower Michigan reports. It’s important that these zones are represented, because it helps provide a clearer picture of where disease-resistant elms may be.

Several Midwest state natural resource agencies and the U.S. Forest Service are working together to identify such locations. They plan to collect branch samples for propagation (the process of growing new trees from a variety of sources), with the goal of developing a seed orchard suitable for future reforestation efforts in northern areas.

Eligible elms must be:

An American elm (not an imported species).
At least 24 inches in diameter.
Disease-free.
Naturally grown, not planted or treated with fungicide
Within 1 mile of Dutch elm disease (indicated by nearby dying/dead elms).

If you come across one of these trees, record its location and diameter at 4.5 feet from the ground. Submit the observation to the survivor elm website.

Ask MG: Why are my elm leaves are turning yellow and wilting?

How do I establish moss on a shady path?

July 23, 2020 • Leave a Comment

We have a shady, worn path on the north side of our house. If I installed stepping stones there, how can I get moss to grow between the stones?

Moss has a unique beauty and has become the focus of a new form of gardening. Since it generally loves acidic, compacted, deeply shaded and poorly drained sites, moss is wonderful for locations that would otherwise be a gardening nightmare.

Four types are typically used in moss gardens: fern (or sheet) moss, the most versatile and fastest-spreading groundcover; rockcap, used for walls, boulders and pond edging; haircap, which prefers partial sun and well-drained soil; and cushion, which prefers sandy soil, tolerates partial sun and is excellent for rock gardens.

In your situation, to get moss to take hold, the first thing you need to do is make sure the growing requirements are met. Think about where you would find it in a natural setting: normally in a shady, relatively cool and damp location, like the woods, shady areas next to a stream, or under a tree where it is shaded, damp and cool.

Do a soil test first. The soil needs to be poor in nutrients and slightly acidic—the pH should be between 5.0 and 6.0; lower is okay, with 6.5 the maximum but not ideal. The soil can be amended to the desired pH with liquid sulfur or aluminum sulfate, or mix in coffee grounds or peat moss. Using Roundup to clear an area of weeds will also help create favorable moss-growing conditions. Moss plants need a firm soil bed rather than loose, fluffy soil, so if the area has been cultivated recently it should be tamped down lightly. Remove any debris, plants, or leaves (moss doesn’t like compost).

Once you have taken care of the soil, you are ready to “plant.” With some patience you can grow your own moss. You will need some moss to start. See if you can find some growing in your yard (or a neighbor’s or friend’s) in conditions similar to where you will apply it. Take a good size strip of healthy moss (remove as much dirt as possible) and crumble it in a blender. Add 2 cups of buttermilk and 2 cups of water. Blend at the lowest speed until it is completely mixed and the consistency of a thin milkshake (add water if necessary). Spread this mixture on the soil. You might need to make more than one batch.

It is imperative to keep the area slightly damp at all times! Keep an eye on it and mist regularly with water, especially the first 3 weeks. It usually takes about a month to get established but it also can take up to a year. The easiest way to ensure success would be to install misters and a timer if the area is not naturally moist or damp. You can use the same mixture (but slightly thicker) to grow moss on rocks, flowerpots, etc. Use a paintbrush to apply the mix and mist regularly to keep it moist.

Having the opposite problem? Dealing with moss in your lawn

New stamps celebrate the beauty of American gardens

July 3, 2020 • Leave a Comment

The U.S. Postal Service has released stamps that celebrate the beauty of American gardens. The stamps feature 10 different photographs of botanic, country estate and municipal gardens taken between 1996 and 2014. The gardens include: Biltmore Estate Gardens (North Carolina); Brooklyn Botanic Garden (New York); Chicago Botanic Garden (Illinois); Coastal Maine Botanical Gardens (Maine); Dumbarton Oaks Garden (District of Columbia); The Huntington Botanical Gardens (California); Alfred B. Maclay Gardens State Park (Florida); Norfolk Botanical Garden (Virginia); Stan Hywet Hall & Gardens (Ohio); and Winterthur Garden (Delaware). To learn more, click here.

Website Extra: A country retreat

June 8, 2020 • Leave a Comment

Editor’s Note: The following are bonus photos from a profile of Vivienne and William Young’s garden featured in the June 2020 issue of Michigan Gardener. To read the full story, pick up a copy of Michigan Gardener in stores or see it in our Digital Edition, which you can read for free at MichiganGardener.com.

Found in the barn, this Stroh’s water trough is filled with sedums and a reading gnome—naturally, it is now part of the reading garden.

A beautiful stone arch frames this quaint seating area adjacent to the barn.

An antique stove is covered with pans and drawers full of succulents.

With its green wicker furniture, the gazebo is a relaxing place to pass a lazy afternoon.

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

Why is my blue spruce struggling?

April 25, 2020 • Leave a Comment

About 4 years ago, a company planted 11 blue spruces in my yard. The following year, 4 of them died and the company replaced them. The next year, 3 died and the company replaced them. Last year 2 died. The soil is mostly clay and that side of the yard sometimes stays damp. I also have a lawn sprinkling system which waters them each day when hot. Any ideas on what’s happening? The remaining trees, now 9, don’t look very blue like blue spruce should, and are kind of yellowish.

Colorado blue spruce (Picea pungens) is native to the Southwestern U.S., not Michigan. It prefers rich, well-drained, yet moist soil in full sun. They are overused by landscapers for screening and large vista plantings because they have greater tolerance for less than ideal growing conditions. Unfortunately, your clay soil holds water like a sponge. “Moist soil” does not equate with saturated soil. Since your yard stays damp and you are augmenting it with lawn irrigation, the roots are simply drowning. The chlorotic needles are also an indicator of excess water in soil that does not drain.

The tree roots are in the top two feet of the soil. Sacrifice some turf grass for 2 to 3 inches of organic compost to enrich the tree roots out to the drip line. Redirect your sprinkling system away from the trees, and reduce the frequency of water, if possible. Consider installing a field drain to move water out of the area. Trees and lawns simply have different water needs.

If you lose any more blue spruces, try replacing them with white spruce (Picea glauca), a Michigan native that also has a pyramidal shape and a blue-green cast to the needles. Consider breaking up the monoculture by interspersing lacy Eastern hemlocks (Tsuga canadensis). They will tolerate more moisture. Still want groundcover? Consider a mix of low-maintenance sun and shade perennials. Canadian ginger (Asarum canadense) works well in shade, and woodland geranium (Geranium maculatum) will work well in the sun-shade margin at the turf line, with a bonus of light purple flowers in late spring.

LEARN MORE: The Blue Spruce at The Morton Arboretum

Why are the leaves on my Japanese maple scorched?

April 14, 2020 • Leave a Comment

I have a dwarf Japanese maple that gets a lot of sun. Last summer I noticed many of the leaf edges were brown and curled. That was the first time I’ve noticed it. The maple is planted near the front of the house so I see it every time I come home. My neighbor had the same problem with his two trees as well.

Although Japanese maples (Acer palmatum) can handle full sun, they do need protection from strong afternoon sun, heat, and wind. Otherwise they respond with the leaf scorch you are observing. Since this was the first time you had seen it, review any changes to the ambient shade it might have originally received in afternoons. Consider your watering frequency. Water thoroughly but less frequently. Make sure the soil is enriched with organic compost and that it is well-drained. Clay soil retains water and drains slowly, encouraging roots to rot. Watering every day never gives the soil a chance to dry out. Provide 2 to 2-1/2 inches of mulch over the root zone to stabilize the surface moisture loss between waterings and keep the soil temperature cooler. If there is no ambient tree shade for the potent afternoon sun, be creative and mount a golf umbrella to a stake to give protection to your favorite welcome-home specimen.

Plant Focus: Pasque Flower

March 31, 2020 • 2 Comments

The spring days are growing longer, the birds are quickly emptying the feeders, and the flowers have begun to emerge. Bulbs like crocus and daffodils are in bloom, but in time, only the old, tattered foliage will remain. Some of the woodland wildflowers, like trillium and bluebells, are also in color, but they too will quickly disappear. Unlike so many early bloomers, pasque flower, will perform well in the spring and continue to be showy well into the summer.

Botanically referred to as Pulsatilla vulgaris, pasque flower sends up purple, reddish, pink or white 2-1/2 inch flowers in April and May. These flowers have 6 large petals (actually sepals) and a bright yellow center. After flowering begins, the spring leaves emerge and are equally showy. These leaves glisten with silky hairs that are exceptionally ornamental.

The performance has just begun, for when the spring flowers finish blooming, the seed pods form. These beautiful, silky, puff balls last well into the summer when all of the flowers have passed. The beautiful spring blossoms and clusters of seed pods make this an outstanding perennial for the front of the border or rock garden. Pasque flower grows 10 inches tall and 10 inches wide, and in our climate, it thrives in both full or partial sun. The plant will last for several years in most gardens, but performs best in a well-drained soil. Rarely does it suffer from insect or disease problems.

Pasque flower is somewhat difficult to find, but is well worth the effort. Young plants offered at garden centers quickly mature to showy clumps of vibrant flowers and striking foliage. ‘Rubra’ is the red form and the species is the purple form (just Pulsatilla vulgaris). These varieties are the easiest to locate, but I especially like the pink form, which, unfortunately, is rarely available. However, a more common German variety called ‘Papageno’ is a wonderful mixture which contains all colors, including the elusive pink.

Take advantage of the many features of this very underused perennial. Few spring-blooming perennials rival the extended display that pasque flower can provide. A tidy habit, wonderful flowers, and beautiful foliage are just some of the traits that make pasque flower a worthwhile addition to your garden.

Pasque flower

Botanical name: Pulsatilla vulgaris
Plant type: Perennial
Plant size: 10 inches wide and tall
Flower colors: Purple (most common), red, pink, or white
Flower size: 2-1/2 inches
Bloom period: April and May
Leaf colors: Silky green
Leaf size: Up to 6 inches long
Light: Full to partial sun
Soil: Prefers well-drained soil
Uses: Front of the perennial border or in the rock garden
Remarks: Leaves appear after the flowers. Silky hairs on the leaves make them glisten. Puffy seed heads form after the flower blooms are finished and are as attractive as the flowers.