The crepe myrtle (Lagerstroemia indica) is cherished for its vibrant summer flowers and attractive, peeling bark. This species blooms exclusively on new growth, meaning flowers develop on wood produced during the current season. Because of this unique flowering habit, proper timing and technique are important when pruning to maintain the plant’s health, shape, and maximize blooms.
Optimal Timing for Pruning
The most effective time to prune crepe myrtles is during late winter or very early spring, generally from January through March, before the plant begins to break dormancy. This period ensures the tree is completely dormant, minimizing the stress from pruning cuts. Pruning while dormant allows the plant to heal the wounds quickly once the spring growth cycle begins.
The specific timing should be just before the new buds begin to swell and show signs of green. Pruning at this time prepares the tree to channel its energy directly into producing vigorous new shoots that will support the summer blooms. This practice encourages the strongest possible growth for flower production without risking damage from cold weather.
Why Timing Matters
Pruning the crepe myrtle outside of the late winter window can have significant negative consequences for the plant’s health and flowering potential. Cutting the branches too early, such as in mid-fall or early winter, can stimulate a burst of tender new growth. This late-season growth does not have enough time to harden off before the first hard freeze arrives. Vulnerable new shoots are highly susceptible to cold damage, which can lead to dieback and increase the risk of entry points for disease and pests.
Furthermore, pruning during the growing season, especially in late spring after new growth has started, directly removes the wood that would have developed flower buds. Delaying pruning too much results in a reduced or delayed summer bloom because the plant must first regrow the necessary branches to support the flowers.
Pruning at the correct dormant stage ensures the tree conserves its energy and uses it most effectively for the upcoming season’s growth and flowering. The absence of leaves during late winter also provides a clearer view of the branch structure. This allows for a more considered approach to shaping the tree and removing unwanted growth.
Techniques for Healthy Pruning
Proper pruning should focus on maintaining the crepe myrtle’s natural, sculptural vase shape through selective thinning rather than indiscriminate cutting. The process begins with removing any dead, diseased, or damaged branches, cutting them back to the point of origin or to healthy wood. It is also important to remove suckers, which are small, vigorous sprouts that grow directly from the base of the trunk or roots, as these detract from the tree’s form and divert nutrients.
Next, focus on thinning the canopy by eliminating small, spindly branches and those that cross or rub against other limbs. These cuts should be made just above an outward-facing bud or back to the branch collar of a larger limb. The branch collar is the swollen area where the branch joins the trunk. The goal is to open up the center of the tree to improve air circulation and light penetration, which helps prevent fungal issues like powdery mildew.
It is essential to avoid “topping,” often referred to as “crepe murder,” which involves cutting large, thick branches back to thick stubs. This practice creates weak, unattractive, clustered growth that cannot adequately support the weight of the summer flowers, often leading to branches drooping or snapping. Topping creates large wounds that are slow to heal, leaving the tree susceptible to pests and diseases, and ruining the plant’s natural, graceful form.