Ask A Master Gardener – Trees for the Small Urban Space

Most people appreciate the splendor of a mighty oak or a majestic maple that can reach 40 to 100 feet in height.  However, many people do not have the space in an urban landscape to plant those larger trees.  Therefore, the tendency is to plant one anyway, and then hope it doesn’t outgrow the space.  A better alternative is to choose a smaller but equally impressive tree.

Small trees are considered to be those less than 30 feet tall.  However, there are some that do not exceed 15 feet.  There are a variety of shapes: round, pyramidal, weeping, upright, and spreading.  Some are sought after for their notable foliage, some for flowers, and some for disease resistance.

Before deciding on the tree selection for a particular location, the homeowner should do a site assessment.  A soil sample is the first and best tool.  Instructions and a submission form can be found at https://uwlab.soils.wisc.edu/soil-samples/lawn-garden/ .  Once you have a sample, evaluate sunlight levels, structure interference, drainage characteristics, soil characteristics, and wind factors.  Plant at least five feet away from sidewalks and pay attention to local ordinances. Once all factors have been considered, it is time to look at trees.

When choosing a tree, it is important to look at diversity. Try to select something that is not already common in the area.  This will prevent catastrophic loss from disease or insect infestation.

Apple Serviceberry, Amelanchier x grandiflora, is a Wisconsin native hybrid that will grow 15–25 feet tall and spread an equal amount. It can be single or multi-stem, with beautiful pink flowers in the spring that turn white as they age. It is a fall beauty with red-orange leaves, attractive bark, and edible berries that attract birds and wildlife.  It is hardy to zone 3a with “Autumn Brilliance” being a cultivar that provides good disease resistance to apple scab.  It will thrive in most soil types and in full sun to part shade.

Eastern Redbud, Cercus canadensis, is another tree that is cold-hardy, especially “Columbus Strain,” hardy to zone 4b.  It has striking purple-pink flowers in the spring and brilliant yellow leaves in the fall.  It grows 20 feet tall fairly rapidly, with an equal spread, in either full sun or partial shade. It can be single or multi-stemmed and will be the one of the first tree to burst into bloom in the spring, with flowers appearing before the leaves.

American Hornbeam, Carpinus caroliniana, is a fascinating tree.  It grows in moist soil, even tolerating some flooding. It grows in shady areas and does well in full sun, tolerating the heat better than most trees.  It will not do well in compacted soil, and instead needs deep, fertile soil.  The smooth gray muscly looking trunk gives rise to its secondary name, the Musclewood tree.  This Wisconsin native will top out at 20–30 feet, but grows slowly.  It, too, puts on a show in the fall with bright yellow-orange leaves.

A proverb says, “The best time to plant a tree was 20 years ago.  The next best time is now.”  If the landscape is small, there are still good choices.  Pick one and start planting.

Carol Shirk

Certified Master Gardener

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