By Carl Wilson, Colorado State University Cooperative Extension, agent, horticulture, Denver County
Small urban lots call for small-sized trees, and thanks to testing at Colorado State University, homeowners have a variety of species to choose from.
Recent research shows better choices to replace some small trees presently grown along the Front Range. Tatarian maple (Acer tataricum) often shows less iron cholorsis than the widely planted Amur maple. Ussurian pear (Pyrus ussuriensis) is more cold hardly and shows less winter dieback than Bradford callery pear.
Preliminary results of tests to find more fireblight-resistant crabapples reveal five promising varieties. Listed with their flower colors, the varieties are Beverly (single pink); Centurion (rose-red); Indian Magic (large, deep pink); Red Baron (red), and Red Splendor (single, rose-pink).
Manchurian apricot (Prunus armenica mandshurica), is well-adapted to Colorado, university tests show. It features a striking appearance with a round-headed shape and lush green foliage. Though it may bear fruit only once in every five years, in this climate, the single, pinkish 1 1-4 inch diameter flowers that appear in April are reward enough for growing this tree. It reaches 12-15 feet high at maturity.
A slightly larger tree with a similar rounded crown is Japanese tree lilac (Syringa reticulata). This plant is notable for its white, 6-12 inch flowers borne in mid-June, as well as its distinctive, reddish-brown, cherry-like bark. The plant presents a stiff, upright appearance and 3-5 inch leaves, slightly less heart-shaped than the leaves of the familiar common lilac.
Also outstanding is a small maple native to the canyons of the Intermountain West. Wasatch or bigtooth maple (Acer saccharum var. grandidentatum), shown above, is one of the best small trees for low water landscapes. This tree grows to a height of 30 feet with a 20-foot spread. The leaves are 3-5 lobed, similar to the eastern sugar maple. Like its distant cousin, Wasatch maple bursts with fall color. Leaves vary from yellow through orange to red.
Similarly, Russian hawthorn (Crataequs ambiqua) also requires less water than other hawthorns planted in this area. A moderately slow grower, it peaks at 25 feet high and l5 feet wide. The plant's best features are the small, pinkish-white May flowers, red fruit in the fall, and glossy, deeply lobed leaves. Like most hawthorns, this tree grows three-eights-inch thorns.
You still have time to plant balled and burlapped or container-grown trees this season, if you act now. Look for some of these small trees at your local nursery or garden center.
Photo: Judy Sedbrook
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010