The crepe myrtle (Lagerstroemia) is a popular ornamental shrub or small tree, cherished for its extended summer blooming period and attractive exfoliating bark. Often called the “Lilac of the South,” it offers vibrant color and year-round interest. Achieving the plant’s long-term health and desired aesthetic appearance relies heavily on choosing the correct planting distance. When selecting a spot for a new specimen, the mature width of the specific cultivar must be the primary consideration for spacing. Proper planting distance ensures the tree has sufficient room to develop its full, natural structure.
Determining Spacing Based on Variety Size
The proper distance between crepe myrtle trees is dictated by the mature width of the variety, not its current size in the nursery container. Growers categorize these plants by size, providing a reliable estimate of their ultimate spread. Miniature and dwarf varieties typically mature to a spread of two to five feet. These smaller cultivars require the least amount of space, often suggested at eighteen inches to four feet apart to allow for individual growth.
Semi-dwarf types reach a mature height and spread between five and ten feet. For example, a cultivar like ‘Acoma’ matures to approximately six to eight feet wide. When semi-dwarf trees are planted as individual specimens, they should be spaced at least eight feet apart to ensure their canopies can fully expand.
Standard or tall crepe myrtles can grow over twenty feet wide and up to thirty feet tall, demanding significantly more room. For a majestic, park-like feel, these large varieties should be separated by twelve to fifteen feet or more. Allowing twenty or more feet between large specimens provides the necessary space for the tree to develop its full, natural vase-like shape.
Adjusting Spacing for Specific Landscape Goals
Spacing based on mature width can be modified to achieve specific landscape goals, such as creating an individual specimen or a continuous hedge.
Specimen Planting
When the goal is a specimen planting, the tree should be planted slightly further apart than its full mature width. This greater distance allows for complete air circulation and an unhindered, full canopy. It also promotes the development of the tree’s unique, sculptural trunk and maximizes light exposure across the entire crown.
Hedge or Screen Planting
When the objective is to create a dense, continuous visual barrier or screen, plants are positioned closer together. For this hedge strategy, a distance roughly two-thirds of the plant’s mature width is recommended. This reduced spacing encourages the canopies to interlock, forming a solid wall of foliage and flowers. For instance, a semi-dwarf variety that spreads ten feet might be planted five to eight feet apart to form a thick privacy hedge.
Avoiding Problems Caused by Poor Spacing
Planting crepe myrtles too close together creates several environmental and health problems affecting long-term performance. The most significant issue is reduced air circulation within the canopy, which increases humidity around the leaves. This humid microclimate is highly conducive to fungal diseases, particularly powdery mildew.
Powdery mildew appears as a white, dusty film that twists and disfigures new leaves, preventing optimal photosynthesis. Closely planted trees also compete intensely for sunlight, leading to leggy, weak growth as lower branches are shaded out. Furthermore, trees positioned too near structures, such as a house or fence, will rub against surfaces, requiring aggressive pruning that distorts the tree’s natural form.