Crape myrtle (Lagerstroemia species) is a handsome, summer-flowering, deciduous small tree or shrub. It is a favorite among Southern gardeners because of its beauty and low maintenance. It has been called the lilac of the south. The most common species in the United States is Lagerstroemia indica. It is native to China and Korea but is naturalized in the Southeast. L. fauriei, native to Japan, is another species found in the United States. Hybrids of the two species generally result in excellent selections. Both species and their hybrids are adapted to all areas of South Carolina.
Heights range from dwarf to semi-dwarf, medium and tall, depending on the cultivar. The height range is from 10 to 30 feet, and width range is 15 to 25 feet. Old specimens can reach 40 feet at maturity.
Crape myrtle grows at a moderate to fast rate, and has a moderate to long life span.
The crape myrtle is valued mainly for its long period of striking summer flowers. These showy flowers may be shades of white, pink, red or lavender. Bloom time varies, depending on the cultivar. Large clusters appear on the tips of new branches beginning in early summer and continue into fall. After flowers fade and fall from the tree, fruit remains in the form of small brown capsules. These fruit remain throughout the winter.
The attractive, exfoliating bark peels away to expose a trunk which ranges in color from many handsome shades of brown to gray. This bark is especially noticeable in the winter months when the tree is leafless. When leaves are present, lower branches can be removed to show off the handsome bark.
Fall leaf color ranges from yellow to orange and red. Although the same plant may display leaves of several colors, the white-flowered types often have yellow fall color, and the pink and red flowered types show yellow, orange and red leaf color in the fall.
Crape myrtle is ideally suited for formal or informal design in the home landscape, street plantings and community plantings. It can be planted as a specimen or in groups, and looks attractive when underplanted with a ground cover; the dark green of the groundcover contrasts well with the handsome bark.
It adapts well to confined spaces, and is, therefore, well-suited for small areas close to sidewalks or parking lots, and can provide shade in deck and patio areas. The flowers of some selections, however, may stain car paint, and the honeydew drops from aphids on the plant may stick on cars or patio furniture. As cultivars are now available in a wide range of growth heights, certain selections can be used under utility lines without fear of interfering with these lines.
The plant typically develops several main stems. These multi-trunk crape myrtles are more desirable than single stem plants in landscape plantings.
The ideal planting site is in well-prepared, well-drained soil, with full sun exposure and good air circulation. Crape myrtles planted in partial or full shade will have reduced flowering and increased disease susceptibility.
The plant will tolerate slightly alkaline to acidic (5.0 to 6.5 pH) clay and other soil textures. Although it tolerates drought, it requires irrigation until it is well-established (approximately two years). This is especially true when it is planted in confined areas.
Heavy nitrogen applications cause the plants to flower less and produce shoot and leaf growth that may be subject to winter injury. Light applications of a complete fertilizer in spring and summer are adequate.
Severe pruning of crape myrtles has become a common practice to maintain shrub size. This ruins the natural, graceful effect of the plant. Many dwarf and semi-dwarf cultivars are now available, making it possible for the homeowner to have the desired plant size while maintaining the natural branching effect. For more information on the pruning of crape myrtle, refer to HGIC 1009, Crape Myrtle Pruning.
Powdery mildew is a common problem with crape myrtle. It is most common during spring and fall. Leaves and young shoots are heavily coated with a powdery, white mold, and may become distorted. Flower buds may not open. Locating the plant in full sun and providing good air circulation helps prevent powdery mildew, but the best approach is to choose resistant varieties.
Fungal leaf spots caused by Cercospora lythracearum may appear on crape myrtle foliage during periods of warm, moist weather. This disease can result in almost complete defoliation of susceptible crape myrtle cultivars during late summer.
Sooty mold is a black coating on leaves that results from a fungus growing on honeydew excretions made primarily by aphids. Plant vigor may be decreased because of the reduction of photosynthesis in the leaves due to shading.
The bark is thin and can be easily damaged by mechanical injury. Mulch around plants to prevent this problem. Vigorous, shallow roots may create problems for healthy growth of underlying plants. Use sturdy ground covers or shrubs to underplant.
Crapemyrtle bark scale (Acanthococcus lagerstroemiae) is a recently introduced pest from Asia, and this insect pest may appear soon in South Carolina. The scale infestations appear as white or gray, waxy crustations on stems, large twigs, and trunks, but rarely on foliage. These bark scales may not kill the plants, but there may likely be a reduction in plant vigor, number of flowers, and flower cluster size. Branches and trunks can become covered in the white scale infestation.
Many crape myrtles are hybrids of L. indica and L. fauriei, developed at the U.S. National Arboretum in Washington, D.C. These were bred for disease resistance, good flowering and attractive bark. (Disease resistance means that infections are few, do not progress very far or do not occur). Some of the selections resistant to powdery mildew include:
- ‘Acoma’ – This shrub/small tree is 10 feet tall and 10 feet wide. Flower is white.
- ‘Muskogee’ – This large shrub/small tree is 21 feet tall and 15 feet wide. Flower is light lavender-pink. Aphids especially like this plant, so sooty mold can be a problem.
- ‘Natchez’ – This large shrub/small tree may grow 25 feet tall. Flower is white, and exfoliating bark is exceptional. This is a favorite.
- ‘Sioux’ – This large shrub/small tree is 15 feet tall and 12 feet wide. Flowers are dark pink.
- ‘Tuscarora’ – This large shrub/small tree grows 20 feet tall and 15 feet wide. Flower is dark coral pink.
- ‘Tuskegee’ – This large shrub/small tree grows 15 feet tall and 20 feet wide. Branching is horizontal. Flower is deep rose.
The following are considered somewhat resistant to powdery mildew:
- ‘Catawba’ – This shrub/small tree is 12 feet tall and 10 feet wide. Flower is dark purple.
- ‘Cherokee’ – This shrub is 10 feet tall and 10 feet wide. Flower is brilliant red.
- ‘Seminole’ – This shrub grows 8 feet tall and 7 feet wide. Flower is clear medium pink. These first flowers can be cut, promoting a second bloom three to four weeks later.
Note: Chemical control of diseases and insects on large trees is usually not feasible since adequate coverage of the foliage with a pesticide cannot be achieved.
For an extensive listing of crape myrtle cultivars and their descriptions, please see HGIC 1023, Crape Myrtle Cultivars.