Winter is when people think about pruning trees, and one of our most commonly pruned trees is the crape myrtle. And it’s usually pruned incorrectly.
Crape myrtles need only occasional pruning, says LSU AgCenter horticulturist Allen Owings.
“An unfortunate trend in crape myrtle pruning is to lop off the tops, which results in a crew-cut appearance. This is often called ‘crape murder,’” Owings says.
The lush growth that occurs at these cut sites appears vigorous but is actually structurally weak and more susceptible to fungus diseases, such as powdery mildew. Worse yet, improper pruning over several seasons results in unsightly large, swollen knobs that form where pruning is done each year.
A gardener should understand that the life of a crape myrtle is shortened, and the natural beauty of the tree is destroyed by this pruning technique, Owings says.
It’s not true that crape myrtles need to be pruned that way to bloom well, he says.
“The flower clusters may be larger on pollarded trees, but the added weight on the ends of long branches causes them to bend over awkwardly, especially after rain,” Owings says. “And because the tree is smaller, it actually produces fewer flower clusters.”
To prune a crape myrtle properly, first decide if it needs to be pruned at all. As 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,” Owings says
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, he advises.
Appropriate reasons for pruning include eliminating crossed and rubbing branches, removing low branches, removing weak, thin branches from the inner part of the tree, trimming off old seed pods, creating a shapelier tree and keeping suckers removed from the base of the trunk.
Avoid cutting back or shortening branches bigger around than your finger, Owings says. But if pruning is needed, cut larger branches back to a side branch or to the trunk.
Got a gardening question? Write to GardenNews@agcenter.lsu.edu.