A crepe myrtle is a popular, fast-growing ornamental plant known for its vibrant summer flowers and attractive, peeling bark. While it naturally grows as a multi-stemmed shrub, training it into an elevated, single or multi-trunk tree structure showcases its beautiful form. This transformation is achieved through selective and timely pruning, guiding the plant’s growth to create a clear trunk that supports an open canopy. The goal is to enhance the plant’s inherent tendency toward a graceful, vase-like profile.
Timing the Structural Cuts
The major, structural pruning necessary to establish a tree shape should be timed precisely for plant health and optimal flowering. The best window for these cuts is during the late winter or early spring, while the crepe myrtle is fully dormant and before new leaf buds begin to swell. Pruning during dormancy minimizes stress and allows the plant to allocate energy toward healing before the active growing season starts.
Crepe myrtles flower exclusively on new wood, meaning blossoms develop on the growth produced during the current season. Pruning before this new growth begins ensures the plant has ample time to produce the wood that will bear the summer flowers. Pruning in the fall or late summer is not advised because it can stimulate tender new growth that is vulnerable to frost damage.
Selecting and Defining the Trunks
The initial, heavy pruning focuses on selecting the permanent trunk structure and removing all competing growth. For a classic tree form, select either a single, straight stem or an odd number of strong, well-spaced canes (typically three or five) to serve as the main trunks. All other stems, especially those that are weak, crooked, or crowding the center, must be removed completely at ground level.
Once the permanent trunks are selected, clear the lower section of the plant to define the tree’s form. This involves removing all side branches and sprouts from the bottom four to five feet of the trunk(s) to create a clean stem, a process often referred to as “limbing up.” Any small, twiggy growth, or “suckers,” emerging from the base or roots must be removed to prevent the plant from reverting to its natural shrub form.
Within the developing canopy, remove any branches that are crossing, rubbing against each other, or growing inward toward the center. Rubbing branches can create wounds that invite pests and disease, so they should be cut back to the main trunk or a healthy outward-facing lateral branch. Thinning cuts—removing an entire branch back to its point of origin—are preferred over topping cuts, which shorten a branch and lead to dense, weak growth.
Maintaining the Tree Form
After the desired tree structure is established, ongoing yearly maintenance is lighter, focusing on preserving the form and encouraging healthy flowering. This involves annual pruning during late winter dormancy to remove dead or diseased wood and to slightly thin the canopy to promote air circulation and sunlight penetration. Removing old seed heads is optional and does not affect the next season’s bloom, as flowers form on new growth.
Throughout the growing season, focus on removing suckers and water sprouts immediately as they appear. Suckers are vigorous shoots that emerge from the base or roots. Water sprouts are fast-growing, vertical shoots that erupt from the trunks or branches. Allowing these to grow will quickly compromise the tree shape and divert energy from the main canopy.
Avoid the practice known as “Crepe Murder,” which is the severe, indiscriminate topping or shearing of the main branches. This harsh pruning creates unsightly, swollen knobs and forces the plant to produce a flush of weak, spindly branches that are often too flimsy to support the weight of summer blooms. A properly trained crepe myrtle only requires selective thinning and the removal of small, pencil-sized branches from the canopy to maintain its graceful, natural shape.