The Crepe Myrtle (Lagerstroemia indica) is a popular ornamental tree or shrub, highly valued for its long season of vibrant summer blooms and attractive bark. Pruning these plants is a widely practiced activity among gardeners, yet it often leads to confusion about the correct techniques. This confusion frequently results in severe, unnecessary cutting that is detrimental to the plant’s health and appearance. Understanding the proper guidelines for when and how to prune the crepe myrtle is necessary to maintain its natural beauty and encourage robust flowering.
When and Why Crepe Myrtles Require Cutting
The optimal time to conduct any significant pruning on a crepe myrtle is during late winter or very early spring, typically between late January and early March, while the plant is completely dormant. Pruning during this period avoids stimulating new growth that could be damaged by late frosts. Since crepe myrtles bloom exclusively on new wood, pruning during dormancy helps direct the plant’s energy into producing new, strong branches that will bear summer flowers.
Pruning should focus primarily on maintenance, structure, and aesthetics, rather than height control. For maintenance, the main goal is to remove any dead, diseased, or damaged wood, a practice often referred to as removing the “3 D’s.” This selective cutting improves the plant’s overall health and reduces the entry points for pests and pathogens.
Structural pruning aims to improve the tree’s architecture, including establishing a strong, multi-trunked framework, ideally limited to three to five main trunks. Thinning the interior canopy increases air circulation and light penetration, which helps reduce the risk of common fungal issues like powdery mildew. Aesthetically, cuts should remove small, twiggy growth and suckers that sprout from the base, highlighting the smooth, peeling bark prized on mature specimens.
Proper Shaping and Thinning Techniques
The correct pruning method for a crepe myrtle involves selective thinning cuts, which maintain the plant’s natural, often vase-like shape. Thinning focuses on removing unwanted branches back to their point of origin (a larger branch, the trunk, or the ground). This technique is less stressful for the tree and promotes a healthier growth response than simply cutting a branch mid-length.
Begin by removing suckers, which are shoots emerging from the base of the plant or the root system. These should be cut off cleanly at ground level or pulled off while they are still young. Similarly, remove water sprouts, which are fast-growing, vertical shoots that emerge directly from the main limbs, as these are structurally weak.
Next, focus on thinning the interior of the canopy to open up the crown to light and air. Remove any small branches that are crossing, rubbing against, or growing inward toward the center of the tree. Rubbing branches can create open wounds, which are vulnerable to disease and pests.
If a reduction in height is necessary, it must be done selectively by cutting a branch back to a strong, outward-facing side branch or bud. Cuts should be made just outside the branch collar, the slightly swollen area where the branch meets the trunk or a larger limb. Arborists recommend never removing more than one-third of the plant’s total height in any single season.
Understanding and Avoiding Severe Pruning
The practice of drastically cutting the main trunks and large limbs of a crepe myrtle back to an arbitrary height is widely known as “Crepe Murder.” This severe pruning, also called topping or pollarding, creates unsightly stubs that result in the formation of large, swollen knobs or “knuckles” if repeated year after year. These knobs remain visible throughout the winter months, destroying the tree’s natural winter silhouette.
Topping stresses the tree and creates large, slow-healing wounds that are open invitations for decay, pests, and fungal diseases. The tree’s reaction is to rapidly produce numerous weak, whip-like vertical shoots from the cut points, known as epicormic growth or watersprouts. These shoots lack the strong wood grain attachment of a naturally grown branch.
The weak attachment makes the new growth prone to splitting and breaking under the weight of summer blooms, wind, or ice. Furthermore, severe topping prevents the natural development of the mottled, exfoliating bark on the upper sections of the trunk, a desirable characteristic of mature crepe myrtles. If the tree has outgrown its location, the preferable solution is to select a smaller-growing cultivar or transplant the tree, rather than subjecting it to damaging, aggressive pruning.