Pruning Landscape Plants
Pruning is an important part of a healthy, beautiful landscape. In this article, we’ll discuss why we prune plants, when they should be pruned and appropriate pruning techniques.
Shape and Size
The most common reasons for pruning is to keep trees and shrubs from outgrowing their space in the landscape. Pruning plants when they are young, and on a regular schedule to maintain shape establishes good structure and prevents many problems as the plant ages. It is far easier (and to remove a twig than a large limb. Unfortunately, a plant that has never been pruned may need to be removed or severely cut back.
Certain growth habits of plants can make plants more susceptible to damage and disease. Crossing branches rub against one another until a wound forms in the bark, creating a doorway for pathogens to enter the plant. Limbs that join the main trunk at a narrow angle are inherently weak, and much more likely to break off as the plant grows. Diseased limbs can be pruned to keep infection from spreading to the rest of the plant.
Fruit and Flowers
Plants can be pruned to encourage flowering and fruiting. This is especially important when maintaining fruit trees and other edible plants in the landscape.
As plants age, they may get leggy or overgrown. This often results in growth only on the outermost tips of plant stems, thinning out of the interior growth, or uneven shape. Rejuvenation pruning encourages new, vigorous growth.
When to Prune?
It depends. The timing of pruning depends on several factors. Most importantly, you must identify the plant you are pruning. This will determine when and how it should be pruned. Some pruning can happen at any point during the year on the majority of landscape plants. Removal of dead or diseased growth and removal of small amounts of growth can be done throughout the year without negatively affecting plants. Otherwise, landscape plants fall into categories that inform pruning timing.
This category includes both evergreen (retain leaves through winter) and deciduous (lose leaves in winter) plants. Generally, plants that bloom before June are flowering on the growth from the previous season, often called “old growth.” If this old growth is removed in late winter, the flower buds would be removed as well. Instead, this group of plants should be pruned just after they bloom. Examples: Azaleas, Camellias, Forsythia, Rhododendron, Viburnum, Bigleaf Hydrangeas.
Plants in this category generally bloom later than June, and they produce flowers on branches that emerge in the spring, also called “new growth.” These plants can be pruned in late winter or any time before growth begins in the spring without fear of removing flower buds. Examples: Abelia, Butterfly Bush, Panicle Hydrangea, Hibiscus, Crape Myrtle.
This category includes plants that are mostly utilized in the landscape for their foliage. These plants should be pruned in late winter, before new spring growth. They can also benefit from pruning later in the summer when growth is complete for the season. This is especially useful for controlling size. Examples: Boxwood, Laurels, Holly, Juniper, Nandina, Spruce.
Have questions about specific plants in your landscape? Check out this great resource from the NC State Extension program: https://content.ces.ncsu.edu/how-to-prune-specific-plants
How to Prune?
Give it a try.
The best way to practice the techniques below is hands-on experience. Grab your pruning tools and head outside. You’ll need a pair of hand pruners, pruning shears, loppers, and a pruning saw (preferably with an extendable pole) to get you started. Read up on these tools and others in this in-depth article from the NC State Extension program: https://content.ces.ncsu.edu/tools-to-make-the-cut
Thinning is a great way to shape plants, direct growth, and remove unwanted growth. Limbs and branches should be removed at the point where they attach to a larger branch. Shrubs that have many branches originating from the ground (like Viburnum and Beautyberry) can be thinned by removing older branches at the ground level. Thinning cuts retain a more natural shape and do not encourage vigorous, dense regrowth.
Heading is the practice of removing currently growing shoots back to a bud. Pinching, tip pruning, and shearing are all types of heading cuts. This type of cut encourages quick, dense regrowth. It is appropriate for maintaining hedges, but should not be the only method used on any plant. Eventually, the dense growth created by heading will shade out the interior of the plant. This will result in a plant that is only actively growing on the very outer branch tips. Use occasional thinning cuts to supplement heading as a strategy for controlling plant growth.
In some cases, a plant is simply overgrown. When normal heading and thinning cuts will not be sufficient to correct the growth of a plant, it may be a candidate for severe renewal pruning. Your landscape professional can help you make this decision. This practice involves pruning branches to a few inches above the ground. Sometimes it is best to remove all the branches of a plant at the same time. In other cases, it is better to remove about a third of the plant growth each season until full renewal is achieved. This should only be practiced on established plants.
A Note About Perennials
While we’ve discussed practices that apply mainly to trees and shrubs, remember that perennials can be “pruned” as well. Perennials can be cut back close to the ground as soon as the foliage dies back following the first frosts, or the foliage can be left until early spring and cut back just before new growth begins. There are advantages to leaving spent perennial growth in the garden. Some species have great winter interest, and some provide seeds and cover for wildlife.
Knowing the correct methods for pruning can be a great asset in managing your landscape. The best way to prune plants, however, is not to prune as little as possible. Choosing the right plant species for your space from the beginning will ensure that the pruning demands of your landscape are only occasional. That means you’ll spend more time enjoying your outdoor space for seasons to come.