The boxelder tree (Acer negundo) is a type of maple that is fast-growing, undemanding and adaptable to a lot of different locations. Native throughout most of the United States, the boxelder is a deciduous tree which does well in U.S. Department of Agriculture plant hardiness zones 2 through 10. It typically responds well to regular pruning, which will strengthen its naturally satisfying growth habit.
Timing
A fast-growing tree, the boxelder benefits from annual pruning, helping it to develop a satisfying shape when the tree is young and to maintain a more mature tree’s size within bounds. Like many maples, the boxelder has ample sap which seeps from cuts when the tree is heavily pruned during its active growth. This produces late winter or early spring, although the tree is still dormant and buds haven’t yet opened, the best time for important pruning. To carry on the tree’s health, remove damaged or diseased branches whenever you see them, at any time of the year.
Pruning
The boxelder will be a weak-wooded tree, making careful pruning of a young specimen important to set up strong trunks and side branches. Young boxelder trees can be trained to a single back or to two or three smaller trunks by eliminating other central divisions and allowing only the desirable ones to stay. As the tree grows, remove side branches with narrow branching angles, and maintain only those strong branches with wide angles of attachment into the back or a bigger branch. Annual pruning of a more mature tree can reinforce the tree’s natural propensity to develop a rounded crown, with longer branches trimmed back by approximately one-third each year to encourage more branching and a bushy and compact growth habit.
Summer Clean-Up
Boxelders tend to produce suckers, which are erect, thin branches which form at the tree’s base, as well as abundant sprouts, which are directly branches that shoot up from the main branches. Suckers and sprouts contribute little to the tree’s growth and can ruin the tree’s naturally appealing form. These thin, narrow divisions can be removed at any time during the growing season without damaging the tree. Also, two branches that cross and rub each other can harm the tree’s bark, supplying an entry route for pests and disease, therefore remove one or both of them at any given time during the growth period.
Characteristics and Requirements
Boxelders reach a height at maturity of 30 to 50 feet with an equal spread. Their leaves have been tri-lobed, resembling those of poison ivy, and frequently turn yellow in the fall. The flowers are inconspicuous and are followed by winged seeds similar to those of other maples. Boxelders are hard, hardy trees that tolerate all kinds of soil and thrive in full sunlight, although they can tolerate some shade. They prefer moist locations and grow naturally along streams or in low, wet places. In cultivation, the trees do well with average moisture and are also adaptable to drier locations.