Pruning Basics
Article by Jessica Warren, ANR Agent, Camden County
As we enter winter, or at least the Coastal Georgia version of winter, it seems like a good time to address the topic of pruning. Not all plants require pruning, and often whether a plant needs to be pruned or not is in the eye of the beholder. Plants may be pruned to achieve and/or maintain a desired size or shape. Pruning may be done to encourage vigorous growth, flowering or fruiting. You may also prune plants to remove damage from insects, diseases or injuries. No matter what your reason for pruning, it’s important to use good pruning practices and proper timing to avoid plants becoming misshapen, reduction in flowers and increased susceptibility to disease, insects and cold damage.
The first step in pruning is having the right tool(s) for the job. Most pruning tasks can be accomplished with hand pruners, loppers, pruning saws and pole pruners. Hand pruners should be used for small twigs and branches up to ½ in in diameter, loppers should be used for branches ½ -1½ in in diameter, and a pruning saw should be used for branches larger than 1½ in in diameter. It’s important to keep your tools clean and dry, and in good working order. At the end of the season you should sharpen and oil blades, and anytime you use tools on diseased plants you should disinfect tools with a bleach solution before using them on another plant.
There are three main types of pruning for trees and woody ornamentals: heading, thinning and drop-crotching. Heading is basically chopping off the ends or top of branches, and is not usually recommended. Cutting off branches from the ends or tips results in thick, compact growth and a loss of the natural growth form, as in the case of a formally pruned hedge. Though sometimes we find this look desirable, it is never a healthy growth form for the plant. This type of pruning results in dense foliage on the outside of the plant, and limits light penetration and air circulation causing a weaker plant and increased susceptibility to disease. Over time the plant’s interior foliage will thin out causing it to look stemmy or hollow. It’s not to say that you can’t hedge, just realize that these plants will need to be replaced periodically as there’s only so long that they can tolerate this unsustainable growth habit.
Thinning is the preferred pruning technique in most cases. Thinning removes an entire shoot or limb back to its point of origin on the main branch (the crotch). Thinning creates a more natural – and healthier — growth form for plants. It is used to shorten limbs or reduce height, improve light penetration and direct or re-direct growth. It is the primary type of maintenance pruning.
Drop-crotching is a form of thinning that is used to reduce the size of large trees. This involves the removal of a main branch or leader by cutting it back to a large, lateral branch. The cut through the main branch is made parallel to the angle of the remaining lateral branch. When removing a large limb, this should be done with a series of three cuts in order to avoid ripping or tearing the bark. The first cut is a notch on the bottom or underside of the branch followed by a second cut from the topside all the way through the branch, a few inches out from where the final cut should be. The third and final cut should be just outside of the bark collar (the swelling where the limb and main branch join). If you cut into the bark collar or the main trunk, you create a much bigger wound that is harder for the tree to heal. If you leave a stub, it creates unnecessary dead tissue that invites rot, insects and diseases. Trees have a natural healing response, and no paints or dressings are necessary.
The most commonly asked question when it comes to pruning is when to prune. Though it can vary by species, there are some easy general rules to follow. Most woody ornamentals are pruned based on the time of flowering. Plants that flower in the spring, such as azaleas, should be pruned after they flower.
Summer flowering plants, such as crape myrtles, should be pruned in the winter dormant season. Pruning spring flowering plants during the dormant season will remove flower buds formed the previous fall, but is not otherwise harmful to the plant. If plants are not grown for flowers, the winter dormant season is the best time to prune. Avoid heavy pruning in the late summer or fall, as this promotes new growth which is at increased risk for cold damage.
Whenever and whatever you may be pruning, aim to use thinning techniques and make sure to address any dead, injured or diseased wood, and any limbs that cross or rub each other – or point downward.