Crepe myrtles (Lagerstroemia indica) are popular ornamental plants known for their vibrant, long-lasting summer flowers and attractive exfoliating bark. These deciduous trees or large shrubs are valued for their multi-trunk structure and relatively low maintenance needs. While the species is resilient enough to survive a radical cut, the long-term advisability of this practice depends entirely on the desired outcome and the plant’s current condition.
The Practice of Severe Pruning
Cutting a crepe myrtle back severely, often leaving only short, thick stumps, is a common practice that most arborists advise against. The tree will survive because it blooms on new growth, but this method sacrifices the plant’s natural, graceful form. This action causes a physiological stress response, forcing the tree to rapidly produce a dense flush of vertical, weak shoots called watersprouts from the cut sites.
These new shoots lack the structural integrity of naturally developed branches and are prone to snapping or drooping under the weight of heavy summer flowers or rain. Over several years, repeated severe cuts lead to the formation of large, swollen, knobby calluses, sometimes called “knuckles,” at the end of the main trunks. These unsightly knobs obscure the tree’s natural beauty, especially during the winter when the smooth, mottled bark should be visible. This aggressive pruning is not necessary to promote flowering and ultimately compromises the overall health of the plant.
When Rejuvenation Pruning is Necessary
A radical cutback is justified only in specific, limited circumstances, typically for an old, severely neglected, or poorly pruned specimen that needs a complete reset. This process is known as rejuvenation pruning and is distinct from the annual practice of topping. The correct timing for this measure is during the late winter or very early spring when the tree is fully dormant, just before new growth begins.
To perform a true rejuvenation cut, the entire plant is cut back to a height of approximately 6 to 12 inches from the ground, essentially coppicing the tree. This forces an entirely new structure to develop from the base, eliminating the knobby growth and weak scaffold branches from years of improper pruning. This method is a one-time intervention to restore the plant’s form, not a yearly maintenance requirement. For dwarf varieties, a severe cutback to within six inches of the ground is sometimes an acceptable method to promote larger, more profuse flowers.
Essential Annual Maintenance Pruning
The preferred approach for managing crepe myrtles involves selective, light thinning cuts rather than radical reduction. The goal of annual maintenance is to maintain the tree’s natural vase shape, improve air circulation, and encourage light penetration throughout the canopy. This work should also be performed in late winter when the plant is dormant and leafless.
A significant task is removing suckers, which are small, vigorous shoots that emerge from the base of the plant or from underground roots. These should be removed as close to their point of origin as possible to prevent them from becoming new, unwanted trunks. Another priority is removing branches that are dead, diseased, or crossing and rubbing against other limbs. Cuts should be made precisely back to the branch collar or to a healthy, outward-facing side branch to allow for proper wound closure. Removing small, twiggy growth, often those thinner than a pencil, also helps to open up the canopy without causing structural damage.
Encouraging Healthy Regrowth
Following a severe rejuvenation cut, the plant will produce a large number of new shoots from the remaining stumps and the ground. Successfully reforming the tree requires careful management of this new growth during the first growing season. Select and retain a limited number of the strongest, most well-spaced shoots, typically three to five per main trunk, to establish the permanent new structural framework.
All other excess new shoots must be removed while they are still young and succulent to prevent a dense, weak thicket from forming. Proper watering is important during this recovery period, especially if the weather is dry, to support the extensive new growth. Delay heavy fertilization until the new shoots have begun to harden off, as excessive nitrogen encourages weak, rapid growth.