Shrub Basics

This is an excerpt from the Book called “Trees Shrubs & Hedges FOR YOUR HOME“. Continue reading to learn more about Shrub Basics, thanks to the author.

Main Facts and Key Details

It’s easy to tell the difference between trees and shrubs. The difference rests primarily in their growth habits. Shrubs have many stems and often have branches that are leafy nearly to the ground. Trees have either one trunk with lateral branches extending out from it, or one or several trunks bare of limbs for some distance above the ground, and topped by a leafy crown.

Shrub Basics

Trees tend to be taller than shrubs, although a large shrub can be taller than a small tree. For example, an upright Japanese maple, profiled in this section of the book, may reach 25 feet tall, while a miniature crape myrtle, profiled in “All about trees”, may grow no more than 3 feet tall. Many other genera of woody plants_ for example, dogwoods, hollies, and junipers_ have both tree and shrub species. But while some species of woody plants are always trees and others are always shrubs, many woody species can develop into either shrubs or small trees, depending on where and how they are grown. Some small trees take on a shrubby habit in parts of their range, and can be guided by pruning to develop either form.

With pruning, even some of the shrubbiest shrubs can be trained into treelike shapes called “standards” and have their lower branches removed in a process called “limbing up” to create a treelike form.

Shrubs, because of their smaller size and bushy shape, have a vital role in the garden, serving as the framework that connects the verticals of the trees and the horizontal lines of ground covers and flower borders and offering an immense variety of form, color, and texture. Enduring from year to year, shrubs provide interest in all seasons and usually need little maintenance. In a traditional herbaceous border, shrubs are the permanent backdrop for showy annuals and perennials. But a simple combination of shrubs and ground covers_ a green garden_ can be attractive and requires minimal upkeep.

Shrubs may be grouped according to their use in landscape design: the flowering shrubs, those grown for their foliage, and those that have interest in fall and winter. Each group includes both evergreen and deciduous plants, large and small, in many forms, as shown on the opposite page.

FLOWERING SHRUBS

The flowering shrubs are an important source of color all year. From the time the forsythias bloom golden in early spring, at least one of the flowering shrubs is in bloom through fall. Some flower all summer long. Small buttercuplike blooms cover the compact, nearly indestructible potentilla from June until frost. Pink Spirea, yellow St. John’s wort, and many hybrid roses bloom form summer into fall. Starting in midsummer, hydrangeas open big blue, pink, or cream pompoms, and the graceful sprays of the butterfly bush a magnet for butterflies from late summer to mid-fall. The sprays of white nandina florets become bright red fruits in late fall and winter.

Shrubs with fragrant flowers, including the mock oranges, the winter honeysuckle, and the fragrant viburnums, can perfume a whole garden. The fragrance of roses is usually more intimate, inviting you to press your nose into the velvety petals. Yet a few, such as the beautiful green-eyed white ‘Madame Hardy’ and David Austin’s ‘Graham Thomas’ scent the air around them.

The flowering broad-leaved evergreen shrubs aren’t as numerous, but they are beautiful in bloom, and their foliage is a great asset the rest of the year. Among the earliest evergreens to bloom, winter daphne bears fragrant flowers in February, and the foliage of the cultivar ‘Aureo-marginata’ is edged with gold. Spring-blooming mountain laurels, pieris, rhododendrons, and azaleas thrive in most, acid, well-drained humusy soil. Clethra blooms in late summer and is fragrant. There are spring-and fall-blooming camellias bred for increasing cold hardiness. The fragrant flowers of late-blooming holly olive still scent the air in November in the mid-Atlantic region and the Pacific Northwest.

FOLIAGE SHRUBS

As dazzling as the flowering shrubs are, ornamental foliage shrubs create a greater effect. Of these, the evergreens, especially the needle-leaved and scale-leaved conifers, contribute the most to the landscape, adding year-round color to the garden plan. Many are dwarf or slow-growing forms of coniferous trees. The rich green, hummocky mugo pine is a standy anchor for sunny corners. Columnar junipers and the showy dwarf blue spruce ‘Fat Albert’ add ever-present texture and color. The aroma of their foliage is a bonus.

The yellow, red, and purple foliage of some of the broad-leaved evergreens_ among them yellow-speckled gold-dust tree (below right), purplish leucothoe, and red-tinged Oregon grape holly-also add year-round splashes of color. But their greens, like those of the conifers, are the mainstay of the garden. Bonwood, evergreen contoneasters, and daphne have fine green foliage that softens a too-vivid color scheme.

Deciduous foliage shrubs excel at providing stunning fall color, in some cases matching even the brilliant sugar maple. Smoke trees and viburmums turn yellow, red, and purple when the weather cools. Perhaps the flashiest autumn foliage appears on the Japanese maples, many of which are red from early spring onward and in autumn rival the red maples crimson. The leaves of some cultivars, such as beautiful ‘Osakazuki’, are yellow to light green in summer and turn a stunning fluorescent red in fall. You can also find season-long foliage color among cultivars of deciduous shrubs, such as barberry and Scotch heather. Shrubs with variegated foliage_ winter daphne and weigela-lighten a mass of darker greens.

PLACING A SHRUB

Besides supplying the framework for the garden, shrubs can screen unwanted sights, define property boundaries, provide a backdrop for flower gardens, guide the eye, and set the overall tone of a garden. When allowed to assume their natural habit, shrubs can make essential contributions to naturalistic and informal gardens. Carefully pruned or neatly sheared into idealized or geometric shapes, shrubs add interest to formal designs. Shrubs can also be massed for screening or retaining soil on slopes, combined with other plants in mixed borders, or planted as focal points or specimen plants.

Plant for color and texture, as well as form, in your design, and keep in mind the changing scene through the seasons. The choices will seem nearly infinite. Your decisions should be based more on the shrubs combinations with one another than with their relation to the perennials, annuals, vines, and bulbs. Because shrubs are such prominent and permanent fixtures, they deserve precedence over the smaller, more ephemeral plants. Certain foliage colors are particularly useful. Green adds weight and stability, while blue-green and gray tone down potentially clashing colors and are good foils for white, pink, purple, or blue. Yellow adds a splash of brightness to a dark corner, while maroon and purple almost vibrate next to acid green.

Shrubs are generally undemanding, provided you get them off to a good start and do not crowd them. Choose shrubs according to their expected height and spread, and give new ones room to grow; fill in the gaps around them with shade-tolerant annuals, such as impatiens and caladiums. It would be a waste of effort to place a wide-spreading shrub, such as a forsythia, in a tight space, where you would eventually need to hack it back and ruin its shape.

In selecting your shrubs, attend to their soil, moisture, and light requirements as well. Remember to account for the encroaching shade of growing trees, and select adaptable species to plant near them.

Pests and diseases usually cause the worst problems when a shrub is under stress. A susceptible shrub squeezed into an airless corner invites an infestation of whiteflies, which love hot, airless spots. A rose in a damp, shady place is much more susceptible to mildew and blackspot than a rose in sun. Rather than struggle with sprays and powders, select disease-resistant varieties, plant them where they grow best, and tend them well.

Once you have chosen the right plant for the right spot, examine the plant carefully before you buy. Like trees, shrubs are sold balled-and-burlapped, bare-root, or in containers. The sidebar below explains what to look for in selecting a container plant. For consumer guidance on root systems in general.

WINTER INTEREST

In the winter garden, the twiggy shapes and colorful stems of leafless shrubs can be an important presence. The bright red stems of the shrubby Tartarian and red-osier dogwoods and the yellow of yellow-stemmed dogwood are striking and decorative. The leafless stems of others have distinctive shapes, perhaps none more fascinating than Harry Lauder’s walking stick.

Berries also add color to the winter scene. Red is supplied by viburnums, cotoneasters, and pyracantha. Species and cultivars of some of these shrubs have orange or yellow berries, as well as blue, white, or shiny black ones. If allowed to develop, the fruits of the rugosa rose and many other roses become red hips. All these shrubs provide birds with welcome meals throughout autumn and winter.

Protecting plants. More plants are damaged or killed in winter than in any other season. They may freeze during a severe cold spell, suffer broken branches from snow and ice, or dry out from winter winds. You can gain protection from drying winds by wrapping evergreen shrubs with burlap, as shown, or by spraying them with antitranspirants.

Guidelines for Selecting Container Shrubs

Poor-quality plants have one or more of these problems:

Bent, broken, or dried-out shoots
Missing or discolored foliage
Container only partially filled with soil; soil dry
Container too small for plant
One or more thick roots coiling near soil surface
One or more thick roots emerging form drains

Healthy plants meet these tests:

Plant size appropriate for container
Small, if any, roots emerging from drain holes
Soil within 1 inch of rim; soil moist
Symmetrical, uniform shape with good foliage color and vigor

Planting Shrubs

Experts agree on the value of matching plants to the soil they prefer. But roots of a woody plant placed in a hole amended with organic materials tend to remain content there, as if in a container. Thus it’s usually better to place new plants in soil typical of that location.

However, amending the soil does make sense when you plant a group of shrubs with similar, particular soil requirement or a bed of shrubs combined with perennials and smaller plants. For example, rhododendrons, azaleas, and other member of the heath family thrive in a raised bed of well-drained, humus-rich, moist acidic soil; many less-fussy shrubs will prosper in the amended soil you have prepared for your mixed border, as long as you allow plenty of room for their roots to grow. Follow the instructions on soil preparation and planting, beginning.

When planting a bare-root

Shrub, such as this rose, spread the roots over a cone of firm, undisturbed soil, first ensuring that the crown is a couple of inches above ground level. A stick or shovel laid over the hole helps gauge proper crown height. Because roses have thorns, heavy garden gloves are recommended.

If the stems of a woody plant

Emerge from the ground too close together, use a spacer to widen the angles between them, to keep them from touching.

Prepare a Container Shrub for Planting

Remove the plant from the container. If it doesn’t come easily with a little squeezing of the container or by tapping its rim against a firm object, cut the container away with a knife or scissors.
Lay the plant on its side, and cut slits on the roots and soil. If the roots have grown too long in an undersized container, they may be potbound, evidenced by circular, tangled, large roots that need to be addressed.
Use your hands to spread the cut sections and tease the roots apart, essentially directing root ends in the spreading configuration in which you want them to grow. Place the plant in a hole.