The crape myrtle (Lagerstroemia) is a popular ornamental tree or shrub in warmer climates, celebrated for its vibrant, long-lasting summer flowers and attractive bark. Its adaptability and spectacular color, ranging from deep reds to whites, make it a favorite landscape plant. This guide covers its successful cultivation and long-term care.
Site Selection and Initial Planting
A crape myrtle thrives when exposed to full sunlight for a minimum of six hours each day. Adequate sun exposure is necessary for robust flowering and helps minimize the risk of fungal diseases. The soil should be well-draining, though Lagerstroemia adapts to various soil types, including clay and sand. Ensure that water does not pool around the roots.
When planting, dig a hole two to three times wider than the root ball but no deeper. The top of the root ball should sit level with or slightly above the surrounding grade so the trunk flare remains exposed. Backfill the hole with the original soil, avoiding heavy amendments that discourage roots from spreading. Planting too deeply is a common error that impedes the tree’s health.
Essential Routine Maintenance
Proper watering is important during the first two growing seasons to establish a strong root system. Newly planted specimens benefit from deep watering every few days, gradually reducing frequency as the tree matures. Mature crape myrtles are moderately drought-tolerant but produce more flowers if they receive supplemental deep watering during extended dry periods.
Crape myrtles do not require heavy feeding, but an application of fertilizer in early spring supports vigorous growth. Choose a balanced, slow-release granular fertilizer or one with a low nitrogen formulation to promote blooms over foliage. High nitrogen fertilizers stimulate leafy growth at the expense of flower production.
Removing spent flower clusters, called deadheading, can encourage a second, smaller flush of blooms later in the season. This practice prolongs the display of color, though it is not necessary for the plant’s health. Maintaining a two to four-inch layer of organic mulch, such as shredded bark, around the base of the trunk is beneficial. Mulch helps regulate soil temperature, conserves moisture, and suppresses weeds, but keep it several inches away from the bark.
Seasonal Pruning Techniques
Pruning should be carried out during the late winter or very early spring when the tree is fully dormant. The goals are to establish a strong structure, increase air circulation within the canopy, and remove undesirable growth. Focus on removing branches that are dead, diseased, or rubbing against other limbs. These crossing points create wounds and entry points for pathogens.
A common error, often termed “crape murder,” involves severely topping the main trunks, cutting them back to thick stubs. This forces the tree to produce numerous weak, unattractive, whip-like shoots. The new growth is often weakly attached, making the branches susceptible to breakage during storms.
Instead of topping, focus on light thinning cuts directed back to a larger branch or the main trunk to maintain the tree’s natural form. Pruning should allow three to five main trunks to emerge from the base for an aesthetically pleasing shape. Remove suckers that emerge from the roots or base, as these divert energy from the main canopy.
Thin out small, twiggy growth from the interior of the canopy to allow sunlight and air to penetrate the center. This increased airflow is beneficial for plant health and aids in disease prevention. When making cuts, always use sharp, sterilized tools to ensure clean wounds that heal quickly.
Identifying and Managing Common Issues
Crape myrtles can encounter pest and disease problems, primarily related to sap-sucking insects. Aphids are the most frequent pest, congregating on new growth and the undersides of leaves. These insects excrete a sugary substance called honeydew, which becomes the substrate for sooty mold, a black, superficial fungus.
Sooty mold does not directly harm the plant tissue, but it reduces the leaf’s ability to photosynthesize light, thereby weakening the plant over time. Managing aphid populations is the most direct way to control sooty mold in the canopy. Small infestations can be washed off with a strong spray of water from a hose.
Larger outbreaks may require an application of horticultural oil or insecticidal soap, which must thoroughly coat the insects to be effective. Apply these treatments in the evening or early morning to prevent potential leaf burn, especially during hot weather. Another common issue is powdery mildew, which appears as a white or grayish coating on the leaves and young shoots in humid conditions with poor air circulation.