February 27, 2019
Guest post by Allen Owings, senior horticulturist at Bracy’s Nursery, a wholesale nursery in Louisiana. This article appeared on Bracy’s Nursery’s Facebook page and is republished here (with light editing) with permission.
Crape myrtles are among the most abused and improperly pruned trees in residential and commercial landscapes throughout the South. Crape myrtles need only occasional pruning, best done mid- to late November through mid-February, to obtain the desired landscape effect. But many times these plants are butchered for no good reason.
An unfortunate trend in crape myrtle pruning is to lop off the tops of the trees, which results in a crew-cut appearance. The lush growth that occurs the following spring at these cuts appears vigorous, but it’s structurally weak and more susceptible to fungal diseases such as powdery mildew. Worse yet, when such pruning is done over several years, large, swollen, unsightly knobs form where the branches are topped. This creates an entry point for fungus, causing stem decay.
Crape murder – don’t do it
Some folks refer to this pruning method as crape murder. Crape murder does not actually kill a crape myrtle. But why are these popular flowering trees pruned this way?
The practice of cutting back the main branches of a tree to the same spot every year is called pollarding. This pruning method is used on some types of trees in certain situations, but it’s more common in Europe than America. You should understand that the life of a crape myrtle is shortened and the natural beauty of the tree is destroyed by this pruning technique. If this is understood, and you decide to pollard anyway, well, that’s your choice.
Many home gardeners think they are supposed to prune their crape myrtles that way. Nothing could be further from the truth. Some have been told that crape myrtles need to be topped to make them bloom better. This is not accurate. Flower clusters may be larger on crape-murdered trees, but the added weight on the ends of long, thin, new-growth branches causes them to droop awkwardly, especially after a rain. And because the tree is smaller, it produces fewer flower clusters.
Can you prune to make a tree smaller?
Sometimes crape myrtles are pruned improperly to create a different shape. A wide variety of crape myrtle varieties are available today. Some grow tall and upright like a vase, while others are shorter and spreading, having more of an umbrella or cascading effect. You cannot make an upright-growing crape myrtle grow into other shapes by cutting it back. The new growth will simply grow upright again. So if you want a crape myrtle that will mature in the shape you desire, make sure you choose one that naturally grows that way.
Sometimes crape myrtles are cut back because they are too large for the location where they were planted. This is commonly seen in crape myrtles planted close to a building. Instead of choosing a smaller-growing variety that would fit next to a house, a homeowner may plant a larger type that then grows into the gutter and roof. To salvage the situation, the owner begins cutting their tree back every year, ruining the natural beauty of the tree in the process.
Choose based on mature size, not just color
Even if you like the result, pruning every year is work that can be avoided by planting the right plant in the right place. For instance, if you want a white-flowering crape myrtle at the corner of your house, select ‘Acoma’, which matures at 10 to 12 feet, rather than ‘Natchez’, which matures at 25 to 30 feet.
When and what to prune
With any pruning project, you must have a specific purpose in mind before you begin. If you can’t come up with a good reason to prune your tree, leave it alone. If you do see something that calls for pruning, study the tree carefully and determine what needs to be pruned to accomplish the specific purpose you’ve identified. Use “art and science” in pruning crape myrtles.
Appropriate reasons for pruning include eliminating branches that are crossed and/or rubbing against each other, removing low branches, removing weak and thin branches from the inner part of the tree, trimming off old seedpods, creating a more shapely tree, and removing suckers (shoots sprouting from the base of the trunk). Avoid cutting back or shortening branches larger than your finger. If you must cut one, prune it back to a side branch or to the trunk.
Proper pruning for happy trees
When you prune only to enhance a crape myrtle’s natural shape, rather than topping it, your tree will have:
- Stronger wood
- More flowers
- Larger flowers
- More pollinating insects
- Enhanced bark features
- Fewer watersprouts (vertical shoots from a trunk or branch)
- Fewer suckers
- More birds nesting
- Less fungal decay in wood
- Fewer insects that cause sooty mold
- Less leaf spot disease
- More air circulation in the canopy
With its smooth, muscular trunks, peeling bark, structure of leafless branches in winter, and exceptionally long blooming season in summer, the crape myrtle is rightfully popular. Make sure you keep yours looking its best.
My thanks to Allen Owings and Bracy’s Nursery for sharing their expertise about pruning one of our most beautiful yet mistreated trees here in the South. Crape pruning has been on my mind since I shared, last week on Facebook, an exasperated plea by Texas horticulturist Greg Grant for people to stop committing crape murder. (I can no longer find that link.) Given my approval of his message, I was surprised when a couple of commenters expressed their own frustration in return about not ever hearing from experts exactly how to prune a crape myrtle. I hope this post provides helpful information in that regard. –Pam
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