Hardiness: Zones 3 to 9, up to approximately 7,000’ in elevation.
Growth habit: Large-maturing, fast growing. Typically has a broad, irregularly rounded canopy with coarse, spreading branches. Some recent cultivars selected for more upright growth habit. Mature height will be typically 60-80’ with a crown spread approximately 50-60’.
Foliage: Rich green deciduous leaves have a wide triangular shape, are alternate, simple, 4 inches long, with serrate margins. Golden yellow in fall.
Flowers: Flowers occur in the spring before the leaves appear, they are dioecious in hanging catkins, meaning both male and female trees occur.
Fruit: Fruits of the female tree give this tree its bad reputation as a “cotton producer” and are 1/4 inch long, 3 or 4 valved capsules that can disperse large amounts of cottony seeds. Avoid this problem by selecting male trees sold in nurseries and garden centers.
Bark: Smooth grayish brown bark becomes deeply grooved as it ages.
Twigs: The twigs are stout, yellowish brown and smooth with a stellate, or star-shaped, pith. The terminal buds are long and resinous.
Insects and diseases: Cottonwood trees in general can host many different insect and disease problems, can sucker sprout profusely, the weak wood often breaks apart in storms and can be susceptible to considerable decay making many selections a poor choice for the landscape. The native Plains Cottonwood, however, shows resistance to many of these problems and the ‘Jeronimus’ selection in particular can be a relatively maintenance-free choice in terms of insect and disease problems.
Landscape value: Give this Great Plains native plenty of above and below ground space to grow. Unlike many cottonwoods, the Plains Cottonwood grows tall and stately and its roots rarely produce suckers in the yard. Only males of the species are sold in nurseries, thus cotton production is not an issue. One of the cultivated male varieties, “Straight Plains” or ‘Jeronimus’ cottonwood keeps a straight main leader, is tolerant of many soil types and conditions, and can make a nice shade tree in landscapes that provide enough room for this tree to mature. Cottonwood is the State tree of Wyoming, Nebraska and Kansas. The Colorado State Champion is located in Loveland.
Cheyenne Wyoming Botanic Gardens
Northern State University and the South Dakota Division of Forestry
City of Boulder Open Space
Keith Wood, Colorado State Forest Service