GardenLine | Trees and Shrubs | Small Plants For Small Spaces

More of us are moving into condominiums or town houses with small courtyards or otherwise limited garden space. In choosing plant material for such spaces, it is important to keep scale and landscape value in mind.

Scale - Large trees, shrubs and flowers will appear to make a small courtyard look even smaller. For small areas, pick plant material small in overall size, and with leaves and flowers that are also small.. One small tree, placed carefully to provide shade, is probably sufficient for a small court yard.

Landscape Value - Where space is limited, choose trees, shrubs, flowers, and groundcovers that provide the greatest range of year-round landscape value. Think in terms of flowers, the color and texture of bark and leaves, and fruit that might be retained through fall and winter. Plants that sucker or are invasive should be avoided. For small spaces, vegetables grown in containers will provide color, food, and visual interest through varied heights.

Trees selected for a small space should be less than 6 m (20 ft) in height, non-suckering, and "tidy" (i.e., not drop twigs). As well, they should require little pruning and be winter-hardy and resistant to diseases and insects.

GINNALA or AMUR MAPLE (Acer ginnala) is a small tree about 4.6 m (15 ft) high. Although it is often seen as a large multi-stemmed shrub, in a small courtyard it is best pruned as a single-trunked tree. The leaves are 3-lobed and will turn a bright red in the fall. It has one of the best autumn leaf colorations for the prairies, but selections will vary in their fall color intensity. The 2-winged seed pods, or samaras, contrast well with the leaves; the pods are red in August and straw-colored in the fall. The ginnala maple is susceptible to lime-induced chlorosis, an iron deficiency that produces yellow leaf blades with green veins. It can be treated with iron chelates used according to label directions.

For something different, try YOUNG'S WEEPING BIRCH. This is a dwarf selection which is low, spreading, and somewhat mound-like, creating a cave beneath its branches. It is usually grafted onto a "standard" trunk of paper birch. It is used as an accent planting or to provide a "hide-away" for children.

FLOWERING CRABAPPLES are small, low-headed trees with white, red, or pink flowers. The fruit is sometimes useful for jelly and is often retained into winter, providing both color in the landscape and food for birds, particularly waxwings. The trees are usually about 4.6 m (15 ft) high with an equal spread. Some have a red-purple summer foliage. It is important to select a variety resistant to fireblight, a bacterial disease. One of the best is Thunderchild, developed by Percy Wright of Saskatoon. It has purple foliage and pink blossoms and it is highly resistant to fireblight.

For a slightly larger space in a more sheltered location, consider the SILVER MAPLE (Acer saccharinum), a nicely shaped tree with a mature height of about 6 m (20 ft). The leaves are 5-lobed, green above and silver beneath, turning a bright yellow in autumn. The bark is an attractive silver grey. The green-winged seedsturn straw-colored in fall. Silver maples must have adequate moisture; although hardy, they are not drought-tolerant. For the best effect in a small landscape, prune to a single trunk.

The LITTLE LEAF LINDEN (Tilia cordata) is another 6 m (20 ft) tree that, if multi-stemmed, should be pruned to a single trunk. The leaves are heart-shaped, shiny, and leathery, and the bark a glossy, reddish-brown. The creamy yellow flowers are both attractive and fragrant and are attached by a stem below the leaves. Linden mites sometimes cause small galls to form on the leaves. Though unsightly, they seldom cause real damage.

The MAYDAY TREE (Prunus padus commutata) is a close relative of the chokecherry but slightly taller and usually pruned to a single trunk. Unless the roots are disturbed, it does not tend to sucker. Large, pendulous clusters of fragrant, pure white flowers are followed by black fruit which provides food for birds. Like the chokecherry, the Mayday Tree is susceptible to "black knot," a fungus disease that can usually be controlled through pruning.

For a slightly larger small space, consider the AMERICAN MOUNTAIN ASH (Sorbus americana). It grows to about 7.6 m (25 ft) with smooth, orange bark and dark green, compound leaves which turn bright orange in mid-September. Small white flowers are produced in May and June, followed by bright-red fruit which persists into winter, providing landscape value and food for birds.

The American mountain ash is more resistant to sunscald than the European mountain ash. Both are susceptible to fireblight, a bacterial disease which is controlled by pruning out infected wood.

A similar but slightly smaller tree is the SHOWY MOUNTAIN ASH (Sorbus decora). It should be noted that mountain ash are easily crossed and there has been much hybridizing within the trade.

For something different try the JAPANESE TREE LILAC (Syringa amurensis japonica), a small tree 6 m (20 ft) in height, with large, trussy, fragrant, creamy white flowers in late June.

The AMUR CHERRY (Prunus Maackii) has bronze, papery, peeling bark. It can be single or multi-stemmed. The white flowers are attractive, formal in drooping dense clusters, and followed by dark chokecherry-like fruit. The leaves turn a soft, golden yellow in the fall. This is a good tree for winter effect. If not hardened up properly in the fall, the Amur cherry may be susceptible to sunscald.

HAWTHORNS (Crataegus crus-galli) are small trees, usually under 4.6 m (15 ft) in height, with a distinctive horizontal branching habit. The glossy foliage turns a brilliant orange-scarlet in fall and the small crabapple-like fruit persists into winter, providing landscape value and food for birds.

Although attractive, the hawthorn has many long slender spines or thorns and is susceptible to cedar-apple rust (a fungal disease) and the occasional pear slug infestation in August. The variety Hopa has double pink flowers and red fruit.

JUMPING POUND PINCHERRY (Prunus pennsylvanica) is a small flowering tree with a distinctive weeping form which tends not to sucker. White flowers in spring are followed by bright red berries (useful for jelly) in late summer.

Part I Sara Williams

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Sustainable horticultural information, offered free of charge to the public with the support of the University of Saskatchewan Extension Division, the Department of Plant Sciences and the Provincial Government.