The Crepe Myrtle (Lagerstroemia indica) is a popular ornamental shrub or small tree known for its long summer bloom period and attractive, exfoliating bark. This plant produces its vibrant flowers exclusively on new wood, which is the growth that develops during the current season. To maximize the summer flower display and maintain the plant’s natural structure, proper and timely pruning is necessary.
The Ideal Window for Pruning
The ideal time to prune a Crepe Myrtle is during its deepest dormancy, specifically in late winter or very early spring (January through early March). This timing minimizes stress because the plant is not actively growing or transporting large volumes of sap. Pruning during dormancy also provides a clear view of the plant’s structure, simplifying selective cuts.
The late-winter window is directly related to the plant’s blooming habit. Since flowers develop on new growth, pruning just before the spring growth flush allows the plant to direct energy into producing the strong shoots that will bear summer flowers. Completing the pruning before new buds swell allows maximum time for flower-producing wood to develop, resulting in a robust display later in the season.
What Happens If You Prune Too Early or Too Late
Pruning at the wrong time can lead to negative consequences, either damaging the plant or eliminating the upcoming bloom. Pruning too early, such as in late fall or early winter, can stimulate tender new growth. This growth is susceptible to freezing temperatures and frost damage, which leads to dieback and creates entry points for disease and pests.
Waiting too long to prune, such as in late spring after the plant has begun to leaf out, will directly remove the new wood. Since the Crepe Myrtle flowers on this new growth, late pruning results in a severely reduced or eliminated bloom display for the current summer. Although the plant’s overall health may not be harmed, the primary ornamental feature—its flowers—will be lost for the season.
Avoiding “Crepe Murder” and Proper Technique
The practice known as “Crepe Murder” refers to the aggressive topping of the plant, where main branches are cut back severely to thick stubs, leaving an unnatural, knobbed appearance. This practice is discouraged because it promotes numerous weak, spindly shoots that are too fragile to support the summer flowers without drooping. Topping also creates large, slow-healing wounds, increasing the plant’s vulnerability to decay and insect infestations.
Initial Cuts
The goal of proper pruning is to maintain the plant’s natural, multi-trunked, vase-like form and encourage strong, healthy wood. Begin by removing the “three D’s”: any branches that are dead, diseased, or damaged. Following this, focus on removing any branches that are crossing or rubbing against one another, as this friction can create open wounds.
Thinning and Heading
Selectively thin the canopy to improve air circulation and light penetration, which helps reduce the risk of common issues like powdery mildew. Make heading cuts—those that shorten a branch—just above an outward-facing bud or a lateral branch to direct future growth away from the center of the tree. Avoid leaving stubs, and for larger branches, cut back to the branch collar, the swollen area at the base of the branch where it joins the trunk.
Removing Suckers and Waterspouts
Remove suckers and waterspouts to maintain the desired tree shape and conserve energy. Suckers are vigorous shoots that emerge from the base or roots of the plant, while waterspouts are fast-growing, vertical shoots that often appear along the main trunks. Removing these close to their point of origin prevents them from diverting energy from the primary canopy.