Late winter or early spring is an excellent time to prune trees. Advantages of late winter or early spring pruning are that gardeners can clearly see the tree structure and remove appropriate branches. In addition, wounds will heal rapidly when growth resumes in spring. Proper pruning should prolong the life of trees. Improper pruning can weaken trees and lead to their premature death.
It is essential to make proper cuts when pruning trees. Do not make flush cuts. Flush cutting results in large wounds which heal slowly. On the other hand, do not leave stubs. When pruning trees, make the final cut just beyond the branch collar and the branch bark ridge. The branch collar is the swollen area at the base of the branch. The branch bark ridge is the dark, rough bark ridge that separates the branch from the main branch or trunk. The primary objective when pruning trees is to make the smallest possible wound which will heal in the shortest possible time.
To prevent the peeling of bark and the creation of large wounds, use the 3-cut procedure when cutting large branches. Make the first cut about 1 to 2 feet from the main branch or trunk. Cut upward and go about halfway through the branch. Make the second cut slightly beyond the first. Cut downward completely through the branch. Make the final cut just beyond the branch collar.
Do not apply wound dressings to pruning cuts. In the past it was a standard practice to seal pruning cuts with wound dressings or paints. It was thought that wound dressings would keep water, insects, and decay-causing microorganisms from entering the wound. It was also believed that wound dressings would encourage healing of the wound. However, scientific research has found that wound dressings actually inhibit or delay the healing of wounds, don't keep out water and insects, and may provide a more favorable environment for decay-causing microorganisms. The best way to insure rapid healing of pruning cuts is to make proper cuts with sharp tools.
Some trees, such as maple, birch, and elm, bleed heavily when pruned in late winter or early spring. However, the heavy bleeding doesn't harm the trees. (The trees won't bleed to death.) Eventually the flow of sap will slow and stop. Heavy bleeding of susceptible trees can be avoided by pruning in late June or early July.
For additional information on pruning trees, pick up a copy of Pm-1304, Pruning Shade and Flowering Trees, at your local county extension office.
This article originally appeared in the March 24, 1993 issue, pp. , 1993 issue, pp. 27-28.