How to Care for Crape Myrtle Trees
Crape myrtle trees (also spelled crepe myrtle and crapemyrtle) are flowering shrubs or trees native to Asia. The common crape myrtle, or Lagerstroemia indica, was imported into the United States in 1747. In the 1950s, a new cold-hearty type of crape myrtle, Lagerstroemia faurei, was imported from Japan. Over 30 hybrids were introduced into the United States around this time, with the most popular being the "Natchez" crape myrtle found in many home gardens throughout the United States today. Both Lagerstroemia indica and Lagerstoemia faurei remain popular garden shrubs, grown for their beautiful and abundant summer flowers and the interesting bark and shape they lend to the landscape.
Which Crape Myrtle Should You Grow?
Crape myrtle trees are fast-growing shrubs or trees. They can be grown in USA hardiness growing zones 6 through 10, but growing them in zone 6 is difficult. Harsh winters can kill crape myrtle trees. They actually prefer hot, humid, and dry conditions and thrive in the intense heat of the southeastern United States.
Because they prefer heat, plant crape myrtle trees in full sun. Without full sun, crape myrtle trees can fail to bloom. Even in partial shade, they'll produce glossy foliage but few or no blossoms.
Choose your crape myrtle tree varieties based on the location available. If you're using them as street or sidewalk plantings, select a taller variety. If you're planting them near your home, choose dwarf varieties.
Some popular crape myrtle tree cultivars include:
- Arapaho—an upright, red flowering crape myrtle tree that can grow 20 feet tall or more.
- Baton Rouge—a miniature red weeping variety that only grows to 3 feet.
- Biloxi—a pale pink, tall-growing crape myrtle tree that can grow to 30 feet.
- Byer's White—a mid-sized crape myrtle of 15-20 feet with white flowers.
- Connestoga—a pale lavender crape myrtle tree that grows about 10-15 feet tall.
- Hopi—a medium pink crape myrtle that attains a height of 10 feet.
- Natchez—probably the most popular crepe myrtle tree. It's white and grows 20-30 feet tall. It has a broader, wider form than other crape myrtle trees, making it a popular landscape tree.
- Red Rocket—has bright red flowers and a tall form, growing to about 20 feet.
There are many more cultivars, but these are some of the common ones found in gardening catalogs and garden centers nationwide.
How to Care for Crape Myrtles
Crape myrtles require several factors in order to be healthy and produce abundant flowers.
- Light: They require full sun, which is defined as six or more hours of bright, direct sunlight per day. Although other plants that require full sun may be able to thrive with a little bit of dappled sunlight in the morning or late afternoon, crape myrtles are fussy about the amount of light they receive. If they don't receive full sunlight, they may not flower. For best flowering, make sure your trees receive plenty of light.
- Water: Crape myrtle trees actually thrive on neglect, which is good news for homeowners and one reason they make great sidewalk trees. You can give them some supplemental watering after planting to help them become established. But after they are established and have set down a good root system, no extra watering other than what nature provides is necessary.
- Soil: They aren't fussy about their soil and can be grown in sandy soil, loam, or clay. They prefer soil with a pH of 5.5 to 7.5, with 6.5 being the best for them.
- Fertilizer: Only young crape myrtle trees need fertilizer, and you can fertilize them twice a year—once in early spring and again in the fall. Use a fertilizer with a ratio of 2:1:1, such as 10-5-5 or 20-10-10.
- Pruning: Crape myrtle trees flower from new growth, so it's important to prune them during the proper season. Prune only in late winter or very early spring, before new leaves and shoots emerge. It's better to under-prune than cut off too many branches. Cut above the joint only.
Insects and Diseases Affecting Crape Myrtles
Like any other plant, insects and disease can attack and infect crape myrtle trees.
Common Insect Pests
The most common insect pest affecting crape myrtle trees is the Japanese beetle. After adult beetles emerge, they feed on many flowering trees, shrubs, and other plants before laying their eggs. The best control method is to take an old can or jar, place a tablespoon of dishwashing liquid inside, and fill the jar halfway with hot, soapy water. Then manually flick beetles into the water. They cannot escape from the soapy environment. A total integrated pest management approach to Japanese beetle prevention and removal is important to keep these scourges in check throughout the garden.
The yellow-colored Crape myrtle aphid may also bother the trees. These insects suck sap from leaves. They thrive on fast-growing shoots and may be attracted to trees that are either over-watered or over-fertilized. So if you see these insects on your trees, cut back on both.
Crape Myrtle Tree Diseases
- Powdery mildew is characterized by a fussy white or silver coating on the leaves. This is a fungus that thrives in moist, humid conditions. Poor air circulation encourages the fungus to reproduce. If your crape myrtle is growing tightly against other trees, try pruning them away. Commercial preparations or horticultural oil treats powdery mildew.
- Leaf spot disease often defoliates most of an entire tree. At first, black or brown spots appear on the leaves, with a yellowish pattern spreading out from the spot. The leaves die and fall off. A spray fungicide treats this condition.
Fortunately, crape myrtles have been bred to be resistant to both these and other diseases. Although insect damage can be a nuisance, these trees are very tough and can often spring back even after a bad year.
Where to See Crape Myrtle Trees
Many gardeners see crape myrtle trees for the first time on a visit to the southeastern United States. During July and August, crape myrtles begin flowering along roadways and streets and in gardens. They've earned the nickname "the 100 day trees" thanks to the beautiful, long-lived flowers. Virginia, North and South Carolina, and Georgia are just some of the many states in which crape myrtle trees thrive. Look for them in bloom in late July through August. Many older homes are graced by stately crape myrtles—truly treasures of the landscape. If you live in zones 6-10, visit your local garden center for help choosing a flowering crape myrtle tree that will thrive in your own yard.
© 2011 Jeanne Grunert