The common Hackberry, Celtis occidentalis, is a large tree that is useful in urban environments. The tree is hardy from zone 2 to zone 9. It will normally grow to a height of 40 to 60 feet and a nearly equal spread. Hackberry trees will grow into a vase shape that is reminiscent of the American Elm, but by no means comparable to it.
Hackberry trees are ideal for northern plains states because it will tolerate adverse conditions of the city environment. It will tolerate winds as well as drought and heat, wind breakage of large branches is a rare if not almost non-existent problem among the species. The species is excellent for park and street use, but is under used as an ornamental tree. It has a bright green color that is offset by the dark drupes that often decorate the tree. The drupes will often hang on well into the winter and into the following spring, adding winter interest. The general species varies widely in the number of fruit set, from year to year as well as from tree to tree.
Propagation is generally accomplished by seed stratification at 40-41 degrees for 60-90 days. The trees can also be rooted but the percentages are usually low. Grafting is also possible if you wish to propagate on of the cultivars.
Cultivars of hackberries are not readily available in the nursery industry, however there are some including Chicagoland, Prairie Pride, and Windy City. Further introductions should be made to increase the availability of the darker leafed and heavier fruiting varieties.
Sources:
Picture Dirr’s Hardy Trees and Shrubs, Michael A. Dirr, 1997
Manual of Woody Landscape Plants, Michael A. Dirr, 4th edition 1990
Plant Propagation, Hartman, Kester, Davies, 5th edition 1990