Ask Mr. Smarty Plants

Lagerstroemia indica (crape myrtle) is native to China and, as such, is not a plant we would ordinarily recommend, as the Lady Bird Johnson Wildflower Center is dedicated to the care and propagation of plants native to North America. However, we do try to help out gardeners with plants they have already purchased, native or not.

Once upon a time, while taking the Master Gardener classes, the Extension Agent for Horticulture proposed to show us how to prune a crape myrtle. She then stood there, with her clippers at her side and did nothing. The point being made there was that the less done, the better. At the other end of the spectrum is the common method used by landscape contractors called "chain saw pruning". This is advertised as a way to promote more blooms, but in our opinion, what it produces is grotesque stubs in the winter and early spring, and then gangly, weak-stemmed trees in the summer. Pruning is best done on the crape myrtle in late winter, which is from about now until the end of February in the Central Texas area. The structure and the decorative bark on the trunks of crape myrtle are some of their chief assets; another reason to object to chopping them off at the knuckles. Pruning should ordinarily involve removing only dead and twiggy growth, thus exposing the structural aspect of the tree.

This Floridata website will give you more complete details on the care of your crape myrtles.