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University of Illinois

Pruning Requires Proper Timing

FOR IMMEDIATE RELEASE
February 28, 2014

Pruning of trees and shrubs must be done at the appropriate time of year with the right tools and have a purpose. Most pruning of landscape trees is done to improve structure, safety and aesthetic value of the tree. The proper pruning practice can increase floral displays or fruit load, prevent snow load breakage and lengthen the tree's life.

Deciduous trees should be pruned while they are in full dormancy. In Illinois that's February or March. Any time before that they are not fully dormant and may produce new shoots that can be killed by future frosts. Anytime during the growing season, pruning cuts will be an avenue for disease and insect infestations.

Prune evergreens in late spring, after the new growth has begun to harden. Pruning early flowering shrubs (those that flower before June 15) should be done in the summer, after the blooms have faded. Examples of spring flowering shrubs are lilac, forsythia and viburnum. Pruning of late flowering shrubs (bloom after June 15) can be pruned in the early spring. Examples of summer flowering shrubs are hydrangea, spirea and hibiscus.

Winter pruning of deciduous trees is ideal because the naked stems allow the gardener to see the structure of the tree and choose the branches to be removed and the branches to be left behind. Horticulture educator Andrew Holsinger notes, "pruning is not only the mechanical process for removing growth; it is also the mental process of knowing what to remove."

Most pruning of young trees should be done after two to three years and after the tree has become established. According to the University of Florida, a tree should be pruned at least seven times in the first 25 years. Pruning larger and more established trees may take several years because you should never remove more than 10 to 15 percent of the canopy in one growing season. Established trees may be too large to safely prune by non-professionals. Homeowners should not prune trees on roadways or near power lines.

A good pruning toolkit would include a good pair of bypass pruners, hand saw and loppers with handles to reach higher into the tree. The handsaw will be useful for large branches and the bypass pruners are ideal for smaller branches and cleaning up wounds.

Pruning tools should be kept sharp and clean. Jagged cuts will not heal properly and be a source of decay. Between working on each tree, tools should be dipped in a sanitation liquid of rubbing alcohol or a 10 percent bleach.

More on pruning trees will be in upcoming articles.

Source: Kelly Allsup, Extension Educator, Horticulture, kallsup@illinois.edu

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