Archive for the shrubs tag

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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