Trees for Small Gardens

Whenever I am called upon to design a small garden, my first concern, after having determined the overall style and feel of the space I’m contemplating, is how to make the garden appear as large as possible. A good designer has a number of visual tricks at his or her disposal to distort the viewer’s impression of distance and make the garden seem more spacious than it really is. One of the most common of these is to run a distinct visual line such as a path or hedge across the longest available axis and place a prominent focal point at its end – the effect being to draw the eye down along the full length of the landscape and concentrate it at a single, distant point, thereby making the garden appear larger than it really is. Many different types of objects can serve as focal points: you commonly see pieces of sculpture, architectural remnants, birdbaths, even outdoor furniture such as benches positioned in this way. But probably my favorite choice for a dramatic focal point in a small garden is a specially chosen dwarf tree. Not only do small trees combine the decorative aspects of both art and architecture, they also have one advantage no inanimate object can ever posses: an ever-changing beauty throughout the four seasons.

Choosing the correct tree for this purpose however can be a bit tricky. The primary consideration of course, is size – if the tree outgrows its space, it can quickly convert itself from art form to artless mess. Secondarily, you want to be sure to select trees that have interest in more than just a single season, preferably something that includes both good summer bloom and exceptional winter form for example, or interesting spring and summer foliage with excellent fall color and fruiting. Finally, you need to take careful stock of your growing conditions: is the space you have in mind baked in sun most of the day, or plunged into shade? Will there be ample root space, or is the available earth area cramped and heavily trafficked. Once again, since the tree will serve both as an important horticultural and structural landscape element, you’ll need to select a specimen that will thrive where you place it. Here are some excellent small trees I’ve had good experience with:

Acer griseum
If I had to limit myself to one tree for small gardens, this may be it. Native to central China, the cinnamon bark maple grows very slowly to just under twenty feet. Its most remarkable characteristic is its exfoliating, cinnamon-colored bark, which peels off in brown wavy strips reminiscent of clouds seen in some ancient Chinese print. Often found as a multi-stemmed clump, the cinnamon bark maple has small, somewhat inconspicuous yellow flowers in the spring, followed by typical wing-shaped maple seeds later in the season. The real show however begins in the fall, when the olive green summer foliage turns a striking crimson– only to set the stage for the exceptional winter silhouette soon to come. A narrow upright tree that prefers full sun, hardy to Zone 5a.

Pyrus salicifolia ‘Pendula’
I must admit a general dislike of weeping trees in small landscapes; they often seem artificial and out of place, compared to say, the flowing natural grace of a full-sized weeping cherry lazily dangling its branches in a stream. This pear relative though, is the exception. Native to Asia Minor and growing (very slowly) to a height of about twenty feet, the cascading gray-green foliage of Pyrus salicifolia ‘Pendula’ is reminiscent of the willow, and makes an outstanding counterpoint to other green foliaged plants in the garden. Although the plant does bear 2 inch fruits, they are largely inedible. The only caveat here is that ‘Pendula’ is very susceptible to fire blight, which can be a major problem outside the Pacific Northwest. Otherwise the plant is relatively trouble free. Hardy to Zone 4a and prefers full sun for best foliage color.

Betula nigra ‘Fox Valley’
For those of you who have longed for the columnar beauty of birch in your yard, but were defeated by fears of the fatal birch borer, or by general lack of space, this may be your chance. ‘Fox Valley’ is a dwarf cultivar of the brown barked River Birch, which grows to about 12 feet high and seems more or less immune to the dreaded birch borer – a pest that can kill a clump of the more susceptible white-barked birch in just a few seasons. Like it’s more famous light-skinned cousins, the bark of ‘Fox Valley’ peels off in gray-brown strips to reveal a lighter, almost pinkish brown under-bark. Individual specimens can very tremendously in this effect though, so it’s best to hand pick candidates at the nursery based on good bark color and trunk form. Like other birches, ‘Fox Valley’ prefers moist sites, though it will tolerate normal garden soil as long as it is not exposed to drought. Summer leaves are medium to dark green, and fall color is a pleasing soft yellow. Hardy to Zone 4/3b, ‘Fox Valley’ will tolerate light shade.

Juniperus scopulorum ‘Skyrocket’
At first glance, this choice seems to contradict my dictum to select small garden trees based on ever-changing seasonal beauty, for the blue-gray evergreen foliage of the Skyrocket juniper remains stubbornly the same throughout the year. The value of this plant, however, is its strikingly narrow, pointed silhouette, and how significant this horticultural version of the exclamation point can be in the landscape. Used alone, or in a group of three, the abrupt verticality of Skyrocket junipers literally call out to you from across the garden, demanding attention. As its name implies, this juniper will grow rapidly to a final height of 15 feet, but even when mature will only be a few feet wide. Full sun, Zone 3a.

So this fall, if your garden seems to be lacking just the right focal point, perhaps it’s time to think about adding a small tree to the landscape. Autumn, with its soft rains and cool temperatures, is the perfect time for planting, and next season, as your tree settles into its new role, you’ll be glad you decided to include such a charming arboreal companion to your garden.

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