Never! Why anyone would want to commit “crepe murder” baffles me. Crepe myrtles naturally grow as a graceful small- to medium-sized tree displaying a beautiful smooth trunk with ascending branches. Most gardeners admire the picturesque shape and richly-colored bark just as much as they do the flowers. As a result, we enjoy spectacular nighttime displays created with landscape lighting set to illuminate the trunk and umbrella-like canopy.
Chopping crepe myrtles back hard every year destroys their shape, looks horrible in winter and encourages numerous sucker sprouts that tend to snap off during summer storms. Dense sucker growth also reduces air circulation and encourages the development of unsightly powdery mildew on foliage. Most who severely butcher their trees every year do so under the belief that this practice makes them bloom more. This is not true; sucker sprouts may produce a larger flower head at their tips but fewer flowers overall are produced on the entire tree.
Proper pruning of crepe myrtles involves shaping the tree to enhance its silhouette by opening up and raising the canopy – just as you would do for most trees. If your site is too small to accommodate a regular-sized crepe myrtle, consider planting a miniature or dwarf variety that will not grow so large: these vary from groundcover forms that only reach 1-inch high to those that peak out at about 8 to10 feet tall. The increasing availability of these innovative varieties should help to decrease the “murder” rate in our landscape!
Darrin Duling is the director of Mercer Botanic Gardens in Humble. He holds The Royal Horticultural Society of England Certificate of Training, The Royal Botanic Gardens; Kew Diploma of Horticulture; and a Master of Science Degree in Plant Taxonomy from the University of Reading, England. He has worked in botanic gardens in England, Thailand, Florida and New York.