Pruning is the most common tree maintenance procedure. Unlike forest trees, landscape trees need a higher level of care to maintain structural integrity and aesthetics. Pruning must be done with an understanding of tree biology because improper pruning can create lasting damage or shorten the tree’s life.
Reasons for Pruning
Each cut can potentially change the growth of the tree; therefore, it is important to remember that no branch should be cut without a reason. Some common reasons for pruning include removal of dead branches to improve form and increase safety, to increase light and air penetration for plants below the tree’s crown, or corrective and preventative measures.
When to Prune
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. Heavy pruning of live tissue just after the spring growth flush should be avoided, especially on weak trees.
Tree diseases, such as oak wilt, can be spread when pruning wounds provide access to disease-causing agents. Susceptible trees should not be pruned during active transmission periods.
If you’re unsure about when to prune, contact your local arborist.
Pruning Techniques
Specific types of pruning may be necessary to maintain a mature tree in a healthy, safe, and attractive condition.
• Cleaning is the removal of dead, dying, diseased, weakly attached, and low-vigor
branches from the crown of a tree.
• Raising removes the lower branches from a tree to provide clearance for buildings,
vehicles, pedestrians, and vistas.
• Reduction reduces the size of a tree, often for utility line clearance. Reducing a tree’s
height or spread is best accomplished by pruning back the leaders and branch terminals
to secondary branches that are large enough to assume the terminal roles (at least one-
third the diameter of the cut stem). Compared to topping, reduction helps maintain the
tree’s form and structural integrity.
• Reducing density of foliage at the crown periphery, thinning, is sometimes performed to increase wind or light penetration for aesthetic reasons and to promote interior foliage development.
