What Should I Know About Pruning Trees?

Pruning trees is an important part of garden maintenance. Regular pruning encourages healthy, even development, attractive arrangements of branches and foliage, and stronger plants. Pruning is especially critical for fruit trees, assuming that the goal is production of fruit, but it also benefits ornamentals when performed on a regular basis.

The rules for pruning trees vary considerably, depending on what type of tree is being pruned. As a general rule, pruning should only be conducted in the winter, when the tree is dormant. Pruning in the spring can cause damage by interfering with new growth, and pruning in the fall may disrupt the tree as it gets ready to conserve energy for the winter. No more than 25 to 30% of a tree's total volume should be removed in pruning, or the tree may be shocked.

Pruning is not the same as trimming, a technique used to shape hedges, shrubs, and trees. Trimming or hedging as it is also known can be performed at various times of the year, using hedge clippers. Trimming usually increases density by removing outlying branches, and promotes an even appearance. It is also used in topiary maintenance.

Several tools are typically necessary for pruning trees. Pruning shears are designed for snipping small branches and shoots, and they come in long-handled and short-handled versions. A pruning saw for thicker branches is usually needed, especially for trees which have not been regularly pruned in the past, and a ladder is crucial, to ensure that all parts of the tree can be reached. For especially large cuts, a pruning sealer can be used to reduce the loss of sap and moisture, although some people feel that sealers increase the risk of rot. It can also help to prune with a partner who stays on the ground for perspective.

In a pruning session, any dead and diseased branches should be removed, along with branches which cross each other or weigh on each other. Adventitious shoots, especially around the base of the trunk, should also be removed, along with branches which look unstable. Branches should always be clipped near a junction, never “tipped,” and cuts should remove branches at the “collar,” the raised area where the branches meet the trunk, rather than being flush or too far out. As the bad branches are removed, additional branches may appear ready for removal for aesthetic reasons.

Different goals can be accomplished by pruning trees. For example, with fruit trees, the idea is to open up the space in the middle of the tree, ensuring that the branches get lots of light so that fruit can develop. In landscaping, people may want to practice crown reduction, which keeps the top of the tree low, especially around power lines, or crown raising, in which branches on the lower part of the tree are gradually pruned away to encourage the top of the tree to grow. Crown thinning is used to keep tree crowns vigorous and healthy by promoting a flow of air and light through the middle of the tree.

There are some safety caveats to keep in mind when pruning trees. Never prune around a utility line without consulting the utility. Always make sure that pruning tools are sharp, for the tree's health, and kept in protective cases, for yours. Keep a pruning ladder on even, level ground, and work with a spotter who can warn you if a position looks dangerous.