About Lagerstroemia indica L.
This species has thin bark, about 2 mm (1⁄16 in) thick; it is smooth, pinkish-gray, mottled, and sheds annually. Its leaves are shed every winter after turning striking autumn colors, and bare branches produce new leaves early in spring. The leaves are small, smooth-edged, circular or oval-shaped, and dark green, changing to yellow, orange, and red in autumn. Flowers on individual trees come in white, pink, mauve, purple, or carmine, with crimped petals, and grow in panicles up to 9 cm (3+1⁄2 in) long. After flowering, the plant produces brown, dehiscent fruits with six capsules.
Lagerstroemia indica is native to subtropical regions of Asia, specifically the Himalayan subtropical broadleaf forests of Nepal, India, Bhutan, and Bangladesh, as well as southern China, mainland Southeast Asia, Taiwan, the Philippines, and Japan. It is commonly planted in the South Atlantic States of the United States, and is becoming an increasingly common shrub in Mid-Atlantic states, ranging north through the coastal areas of Massachusetts. It also grows well in the Mediterranean and Desert climates of Southern California, Arizona, and Nevada, and is planted as a street tree in Australia.
In the United States, Lagerstroemia indica is a very popular flowering shrub or small tree in mild-winter states (USDA Zones 6–10). Its low maintenance requirements make it a common municipal planting in parks, along sidewalks, on highway medians, and in parking lots. Like southern magnolia, crape myrtle (the common name of this species) has become a symbol of the American South, due to its extensive planting and ability to thrive in hot, humid summer climates with regular precipitation. It is one of the few trees or shrubs that produces bright, showy color from late summer through autumn, when many other flowering plants have already finished blooming. In arid climates, it needs supplemental watering and some shade in the hottest locations. The plant requires hot summers to flower successfully; without this heat, it produces weak blooms and is more susceptible to fungal diseases.
L. indica is often root hardy to Zone 5 (−23 °C or −10 °F), meaning top growth will be killed back during harsh winters, but the plant will regrow from its roots and flower in summer. Because of this, Northern gardeners grow it more like a perennial than a tree or shrub. Excess watering and over-fertilizing can reduce cold hardiness, as these practices stimulate late-season new growth that does not have time to harden off before cold weather.
Lagerstroemia indica is frost tolerant, prefers full sun, and will grow to 6 m (20 ft) tall with an equal spread of 6 m (20 ft). It is not particular about soil type, but requires good drainage to thrive. Once established, it is quite drought hardy, though it benefits from occasional deep watering during summer months. The US National Arboretum has developed 15 hybrid cultivars between L. indica and L. fauriei, selected for improved cold hardiness and disease resistance; all of these cultivars are named after Native American tribes. Dwarf cultivars exist for both L. indica itself and indica × fauriei hybrids, which grow to between 0.6–1.5 m (2–5 ft) in height.
