Gardening Tips: Pruning Crape Myrtles
For the past two years, I have been taking classes at NC State in the Agriculture and Extension Education department. This semester, my course is on using technology in extension teaching. A few of my assignments have been to start a blog, join Twitter and upload a video to YouTube. You can find the information about my blog and Twitter at the bottom of this article, but I’d like to first talk a bit about the video I made.
The video I made is an instructional video on how to prune crape myrtles. At the risk of hurting some feelings, I have to point out that almost everyone who prunes crape myrtles does so incorrectly. It is probably the biggest gardening mistake people make in our area. I knew that this was the topic I needed to address for this assignment.
Generally, people do their crape myrtles a disservice by pruning them much too aggressively. I understand that there are many reasons why they do this- confusion over whether to treat the multi-trunked crape myrtle as a tree or a shrub, mistakenly thinking that heavy pruning is the only way to produce adequate blooms each year, feeling overwhelmed by a plant that has gotten much bigger than anticipated, or simply copying what they see many of their neighbors doing. However there are several reasons why this type of pruning is harmful.
Though they have more than one trunk, crape myrtles are in fact trees and should be treated as such. What other trees do you chop down yearly to a four-foot tall sump? None of course! When pruned so heavily, the crape myrtle responds by altering it’s future growth. Instead of continuing in it’s natural form producing strong, arching branches leading to a vase or umbrella shape, heavy pruning causes the new growth of a crape myrtle to produce many vertical branches that are relatively weak. In addition, the smooth colorful trunks of the crape myrtle often become gray and dull after repeated heavy pruning and develop knobs on the stems where the pruning has occurred. The result is a much denser, less graceful looking tree that bears no resemblance to a naturally growing crape myrtle.
So how should they be pruned? Relatively sparingly, truthfully speaking. If you watch the demonstration video on my blog, you’ll see that my main objectives when pruning crape myrtles are first to remove low branches to highlight the trunks and to prevent a shrub-like appearance, and second to selectively thin the top half of the tree by removing branches that are dead, damaged, touching or crossing other branches, or headed in an undesirable direction. The finished tree looks like a cleaner, neater version of what I started with, not a new tree all together.
Matthew Stevens is the horticulture extension agent for Halifax County Cooperative Extension. You can follow Matthew on Twitter @halifaxgardens or visit his gardening blog halifaxgardens.blogspot.com. If you have any questions about this article or other aspects of your home gardening, please contact Matthew at 583-5161 or firstname.lastname@example.org