Most light, routine pruning to remove weak, dead, or diseased limbs can be accomplished at any time during the year with little effect on the tree. As a rule, growth and wound closure are maximized if pruning takes place before the spring growth flush. Some trees, such as maples and birches, tend to “bleed” if pruned early in the spring. It may be unsightly, but it is of little consequence to the tree.

The amount of live tissue that should be removed depends on the tree’s size, species, age, and pruning objectives. Younger trees tolerate the removal of a higher percentage of living tissue better than mature trees. Generally, no more than 25% of the crown should be removed at once, and less for mature trees. Removal of a single, large-diameter limb can create a wound that may not be able to close. Care should be taken to meet pruning objectives.