Crepe myrtles (Lagerstroemia indica) are popular ornamental trees and shrubs recognized for their colorful, long-lasting summer blooms and distinctive, often exfoliating bark. These plants offer significant visual interest in the landscape, even during the dormant season, due to their smooth, multi-toned trunks. To maintain the plant’s natural structure and ensure abundant flowering, proper pruning is an important part of their care. Understanding when and how to make cuts directly influences the tree’s health, appearance, and flowering potential.
The Optimal Pruning Window
The single best time to prune a crepe myrtle is during the late winter or very early spring, generally from late January through March, before new growth begins to sprout. This timing is synchronized with the plant’s full dormancy, which minimizes stress and allows the gardener to clearly see the branch structure without leaves. Pruning during this period is beneficial because crepe myrtles bloom on “new wood,” meaning the flowers develop on the current season’s growth. Cutting back prior to the new growth cycle encourages the plant to produce strong, vigorous new shoots that will support the summer flowers.
This dormant-season pruning promotes the proper healing and compartmentalization of pruning wounds before the tree actively begins its spring growth. It is important to monitor local weather conditions and avoid pruning immediately before a severe freeze. A hard frost on fresh, open cuts can cause dieback or damage. Waiting until the late end of the dormant season, such as late February or early March, can be a safer approach in colder regions.
Defining Proper Pruning Methods
The goal of correct crepe myrtle pruning is to maintain the tree’s natural, sculptural form and create a healthy structure, not to drastically reduce its size. Pruning should focus on selective thinning to improve the overall health of the plant. This involves removing dead, diseased, or broken branches, and any branches that cross or rub against each other.
Another important task is to remove small, twiggy growth, often referred to as suckers, that sprout from the base of the trunk or along the main branches. Thinning the canopy by removing interior branches allows for better air circulation and light penetration, which helps reduce the risk of fungal issues. Proper cuts are made just above an outward-facing bud, or back to the branch collar where the branch joins a larger one.
Differentiating between cut types is important for long-term tree health. A “thinning cut” removes an entire branch back to its point of origin on a larger branch or the main trunk, which is the preferred method for crepe myrtles. Conversely, a “heading cut” involves cutting a branch back partway to an arbitrary point, which stimulates multiple weak shoots to grow just below the cut. The severe and improper practice of topping the main branches, known as “Crepe Murder,” is a form of heading cut that leaves large, unsightly stubs.
Consequences of Mistimed or Excessive Trimming
Pruning outside the recommended late winter window can have serious negative effects on the crepe myrtle’s health and flowering. Pruning in the late summer or fall is particularly detrimental because it encourages a flush of tender new growth. This late-season growth does not have enough time to harden off before cold weather arrives, making it highly susceptible to damage from freezing temperatures. Pruning in the spring removes the new wood that would have produced the current year’s flowers, resulting in fewer or delayed blooms.
The extreme reduction of the tree’s canopy, known as “Crepe Murder” or topping, should be avoided entirely. This excessive trimming removes strong, established scaffold branches, which ruins the tree’s graceful, natural appearance. The severe cuts from topping do not heal well and create large wounds that serve as entry points for disease and wood decay. In response to this trauma, the tree produces a profusion of weak, spindly shoots, often called epicormic growth, at the site of the cuts.
Repeated topping leads to the formation of unsightly, knobby swellings at the end of the cut branches, which detract from the plant’s appearance year-round. These new branches are poorly attached and often too weak to support the weight of the summer flower clusters, causing them to droop or break, especially after a rain.