Crepe myrtles (Lagerstroemia indica and its hybrids) are prized landscape trees known for their vibrant summer flowers, smooth, exfoliating bark, and attractive fall foliage. A common frustration arises when the tree exceeds its intended height, growing too large for its location. Safely managing the size of an overgrown crepe myrtle is entirely possible and involves specific pruning techniques that maintain the plant’s health and natural form. The goal is to reduce the canopy without causing long-term damage, ensuring the tree remains a beautiful feature in the landscape.
Understanding Crepe Myrtle Growth Habits
A crepe myrtle becoming too tall is often a result of either initial poor selection or previous management decisions. Many popular cultivars, such as ‘Natchez,’ ‘Tuscarora,’ or ‘Muskogee,’ are naturally large trees that can easily reach heights of 20 to 30 feet at maturity. Planting these large varieties near a house or under utility lines inevitably leads to an oversized tree requiring heavy pruning.
The average crepe myrtle grows at a medium-to-fast rate, sometimes adding between one to two feet of height annually. If a large-statured variety is planted in a small space, it will quickly outgrow the area and create a height problem. The tree’s propensity for rapid, vertical growth is also exacerbated by improper past pruning, which encourages the plant to send up numerous weak, fast-growing shoots.
Avoiding Severe Pruning Damage
The most common mistake when attempting to reduce the height of an overgrown tree is the indiscriminate cutting of large branches back to thick stubs, a practice often referred to as “crepe murder.” This technique, which involves topping the main trunks at an arbitrary height, is detrimental to the tree’s health and appearance. Topping removes a large percentage of the tree’s stored food reserves and forces the plant into a survival mode of growth.
The immediate reaction to topping is the rapid emergence of a dense cluster of multiple, thin, whip-like shoots just below the cut site. These shoots are structurally weak, often unable to support the weight of the summer flowers, causing them to flop over. Repeated topping causes the development of unattractive, swollen knobs or “knuckles” at the ends of the cut trunks. Furthermore, the exposed cut surfaces are slow to heal, providing easy entry points for wood-decay fungi and insect pests.
Corrective Structural Pruning for Height Reduction
Bringing an overgrown crepe myrtle back to a manageable size requires a gradual, strategic approach that focuses on proper arboricultural cuts. This process should be undertaken over two to three dormant seasons to minimize stress on the tree. The technique relies on two specific types of cuts: thinning cuts and reduction cuts.
Thinning involves removing an entire branch back to its point of origin, either the main trunk or a larger supporting limb. This technique helps to open the tree’s canopy, improves air circulation, and reduces the overall density of the crown without stimulating excessive regrowth. Thinning cuts are used to eliminate crossing, rubbing, or inward-growing branches that clutter the center of the tree.
Reduction cuts are employed to decrease the length of a branch by cutting it back to a smaller, lateral branch or bud that is growing in an outward direction. For corrective height reduction, a reduction cut should be made to a side branch that is at least one-third the diameter of the limb being removed. This size ratio helps ensure the remaining lateral branch will assume the role of the terminal leader, redirecting growth away from the top of the tree. By consistently using reduction cuts to lower the height of the tallest branches, the tree’s natural shape can be restored without creating stubby, unstable growth. This careful reduction process should be performed during the tree’s dormancy, ideally in late winter or early spring before new growth appears.
Annual Maintenance for Consistent Size
Once the initial height reduction is achieved through structural pruning, maintaining the tree’s size becomes a simpler, annual task. Pruning should be scheduled for late winter, generally between January and March, when the tree is dormant and the branch structure is visible. Pruning during this window ensures the tree’s summer bloom cycle, which occurs on new growth, is not negatively affected.
Routine annual maintenance focuses on removing branches that detract from the tree’s aesthetic and structural integrity. This includes eliminating suckers, which are fast-growing shoots that emerge from the base of the trunk or the roots, as well as water sprouts, which are vertical shoots that grow rapidly from horizontal limbs. Removing these shoots with a clean cut back to the source prevents the tree from reverting to a bushy form and redirects energy toward canopy development.
The annual pruning should also remove any small, twiggy growth, which helps maintain an open canopy and highlight the attractive, mottled bark of the mature trunks. If the tree is a variety that reblooms, light shearing of the spent seed heads in mid-summer can encourage a second flush of flowers. These light, selective cuts are the long-term method for ensuring the crepe myrtle retains a healthy, manageable size appropriate for its space.