The crepe myrtle (Lagerstroemia spp.) Is an attractive, multi-stemmed shrub or tree that’s named for its blossomsthat resemble colorful crepe paper. Several types exist, including the common crepe myrtle (Lagerstroemia indica), also a 25-foot-tall plant, and also the Japanese crepe myrtle (Lagerstroemia fauriei), which is now 50 feet tall. These plants develop in U.S. Department of Agriculture plant hardiness zones 7 through 9 and 6 through 9, respectively. In zone 9, crepe myrtles leaf out in spring and bloom in summer, together with some minor differences from year to year.
Ancient Spring Growth
The crepe myrtle is deciduous, dropping its leaves and becoming contaminated during winter, when it consumes little if any water through its roots. At USDA zone 9, winter temperatures may drop to 20 or even 30 degrees Fahrenheit for short periods of time, with the last frost typically occurring in early March. The first signs of new life on a crepe myrtle look a couple weeks later, once the inactive, or inactive, buds start to swell as the shrub begins taking up water in the soil, which starts to warm. Although spring temperatures may vary from year to year, the crepe myrtle typically has small, new leaves revealing on its branches a couple weeks after the last frost in zone 9, or at late March or early April.
A Great Spring Start
Mulching the area under a crepe myrtle will keep its roots warm during winter and early spring, however, do not mulch the plant till it’s become leafless and dormant in the fall or early winter. Mulching earlier while it’s still growing may keep the roots too warm and prevent dormancy, risking cold injury to the plant when winter arrives. Add 3 or 4 inches of straw or shredded bark on the ground under the plant’s canopy, keeping mulch back in its base to prevent moisture accumulation. In early spring, remove the winter mulch to get rid of overwintering insects and their eggs, renewing it with a brand new layer to help conserve soil moisture during the upcoming season. In spring, when you observe buds begin to swell, then water the crepe myrtle regularly to get it off to a good start, but do not overwater. Aim for approximately 1 inch of water weekly, including rainfall.
Summer Flowering
Like all plants, the crepe myrtle gets a signal to begin flowering when days get more as the season progresses. The specific timing of flowering may vary a bit among the various cultivars, but generally crepe myrtles start blooming in mid or early season, and they frequently continue thriving through summer and into early fall, with some varieties flowering until the first frost. You can prolong blooming on a crepe myrtle by removing spent flowers before they dry and produce seeds, called deadheading. This stimulates the plant to set out another flush of blossoms, although this may be smaller compared to the initial crop of blossoms.
Potential Problems
The crepe myrtle is generally a powerful, easy-to-grow plant, but it can attract aphids, soft-bodied insects that suck sap from leaves and can cause them to wilt and dry up. If uncontrolled, aphids may also assault blossom buds and destroy them until they open. Aphids are best controlled by spraying the crepe myrtle with insecticidal soap, diluted at a speed of 6 tablespoons per gallon of water. Spray until all plant parts are dripping wet, and repeat each week or 2 as required. Crepe myrtles can also be prone to powdery mildew, a fungus that causes fluffy white spots on leaves, and sooty mould, another fungus that grows as blackish, fuzzy places. Both may interfere with development of foliage and flowering. They’re best prevented by planting a crepe myrtle where air cools well, regularly clearing away debris from under the crust, and watering only with a soaker hose or drip irrigation to keep foliage dry.