Pruning is defined as “removing plant parts for a purpose.” Some plants need pruning every year, some need just an occasional touch-up, and some never need to go under the knife. Never prune without a purpose in mind. Good reasons to prune include:
Timing is very important. For disease prevention reasons, winter is the best time to prune oaks, elms, fruit trees, crabapples, mountain ash, and hawthorns. Dead, diseased, or broken branches should be removed on these, and other plants at any time of year (use sealer). Timing is also very crucial for fruiting or flowering plants. In general, plants that flower early in the season should be pruned after flowering; plants that flower later should be pruned early in the spring. See the Dundee Fact Sheet, “Pruning Guide - Timing” for specific information.
Bareroot trees should have their side branches cut back about 1/3 at time of planting. Balled and burlapped, or container-grown trees usually need little, if any, pruning when planted if no root damage occurred at that time. Remove any suckers or watersprouts (weak, fast-growing shoots from the roots or on the main stem.) Don’t be in too big a hurry to shape a very young tree. They need all the leaves they can get to grow fast. Only prune young trees to correct faults, i. e., double leaders, crossing branches, or very narrow crotches. In a few years, you can start establishing the ultimate shape, i.e., removing lower branches so you can walk under them (no, they won’t get higher off the ground as the tree grows). Fruit trees should be pruned so they have an open habit. This allows sun to penetrate to the interior, encouraging more fruit to form. Branches with wide crotches will be stronger. Evergreen trees generally look best if their natural form is retained. Very young evergreens can be pruned to thicken them, otherwise only prune them to correct defects, such as double leaders.
Hedges can be allowed to grow naturally to provide an informal screen. These will need only an occasional pruning to keep them thick. Hedges can also be made to look quite formal, requiring regular, severe shearing. This should be started at an early age. For best results, keep the bottom broader than the top, allowing the bottom leaves to receive their fair share of sun. For other shrubs (not hedges), there are two basic ways to prune. Young shrubs can be pruned lightly to shape and thicken. This usually means pruning up to 1/3 of the height. Do not give the plant a flat top. Try to keep its natural form in mind. Large, overgrown shrubs will benefit from renewal pruning. This involves cutting 1/3 of the branches (choose the oldest) clear to the ground with light shaping of the remaining stems. Evergreen shrubs such as spreading junipers and arborvitae benefit from a light shaping (just the succulent new growth) every spring. Don’t wait until evergreens are way too big, as they do not accept severe renewal-type pruning.
When pruning small branches, cut back to 1/4” above a side branch or bud. Don’t leave dead stubs as they will attract disease and insects (this is why topping a tree is not recommended). Avoid tearing the bark when sawing off large branches. The first cut should be an undercut about 18” from the main trunk. Then cut off the bulk of the branch. Old pruning books may show that the final cut should be quite flush with the trunk. Research shows that leaving the branch collar intact will inhibit decay and speed healing. Therefore, your final cut should leave the branch collar intact.
Pruning sealer is not recommended except on plants that have disease and/or insect problems which are exacerbated by open wounds, especially if the pruning occurs at the wrong time of year. Examples of plants that fall into this category include fruit trees, oaks, elms, hawthorns, mountainash, and crabapples. If you have these plants on your property, it is a good idea to have a can of pruning sealer available at all times, in case of accidental damage.
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