Crape Myrtle Care

by Elmer Krehbiel, Master Gardener
July 16, 2004

Crape myrtles are one of the best warm-season landscape shrubs in the southern states, producing beautiful flowers during the summer and fall and colorful leaves during the fall months. During the dormant season, the larger varieties of crape myrtle develop attractive bark.

Choosing Varieties

  • Shrub and tree forms exist.
  • Mature size ranges from 2 to 30 feet.
  • Upright and spreading (weeping) forms available.
  • Choose a variety of appropriate size for location.
  • Choose varieties with powdery mildew resistance for easier maintenance.
  • Flower colors include white and many shades of cream, pink, red, rose, orchid, lavender and purple.
  • Some flowers have frosted or two-tone petals.
  • Trunk mottled in shades of sable, tan and brown
  • Fall foliage color may be red, orange or yellow.

Site Selection

  • Choose a site with full sun or as much sun as possible.
  • Choose a site that is tolerant of a wide range in soils.
  • Crape myrtles grow better and larger on light, well-drained soils
  • Choose an open area, if possible, for good air movement to reduce the incidence of powdery mildew (see section on Pests and Disease).

Planting

  • Dig hole 1 to 2 feet wider than diameter of root ball
  • Set the top of the root ball level with the soil around it
  • a) for large balled and burlapped or container grown plants, dig hole the same depth as the root ball so that the top of the root ball is even with the soil line,
  • b) for small plants (1 to 5 gallons), dig hole deeper than the root ball, hill and firm soil to set top of root ball even with the soil line.
  • Plants set too deep or shallow grow poorly and may die.
  • Build levee (see diagram1 or diagram 2) of soil around perimeter of dug area to create basin for thorough watering.
  • Mulch area around base of plant with 1 to 2 inch depth of compost, composted bark, pine straw, etc.

Light, Soil & Water

Crape myrtles grow best in in a location of full sunlight, moist fertile loam soil with good drainage, and good air circulation. They can tolerate considerable heat, humidity, drought, or excessive moisture, but not shade or poor aeration.

  • Water crape myrtles thoroughly during dry spells.
  • Water more frequently in the first two years.
  • Although older plants are somewhat drought tolerant, irrigation during dry spells will enhance performance.

They prefer soil with  medium to high fertility. Both soil and water should be within the pH range of 6.5 to 7.5, and in the Brazos Valley, local water has a pH of 8.5. To hold in moisture, apply mulch around around your crape myrtle plants, so that only a limited amount of local water is needed. They will do better are when rainfall is sufficient for them.

  • Fertilize with either complete inorganic or organic fertilizer or combination of both.
  • Apply compost or other organic mulch materials to total depth of 1 to 2 inches over soil area extending from trunk to just beyond spread of branches.
  • Replenish organic mulch as needed.
  • Apply inorganic fertilizer with 3-1-2 ratio of N-P-K in February or March at rate of 1/2 to 1 lb. per 100 sq. ft.; also apply 1/4 to 1/2 lb. per 100 sq. ft. or a 1-2-1 ratio of N-P-K in May or early June to encourage good bud set; 
  • Spread fertilizer over feeder roots in a zone extending from just beyond drip line of canopy to half the distance inward toward trunk.
  • Do not apply inorganic fertilizers near trunk.
  • Do not use fertilizers containing herbicides.

If conditions are poor, can they be improved for crape myrtle? There are limits to this approach. I had to move all five of my shrubs because of bad air circulation and shade from a board fence and a tree.

  • Crape myrtle grow better in moderately moist soil than in extremely dry or wet soil.
  • Flowers develop on new growth. Gardeners should provide the best conditions for the roots in order to produce growth and flowers.
  • Crape myrtle shrubs sprout multiple permanent stems. The sizes and shapes of different varieties are due to genetic traits.

Pruning Crape Myrtle

A gardener wishing to develop a tree form of crape myrtle with a single or a few trunks should select a variety that has an expected tall mature size. Then, as new stems continue to sprout at the base of the shrubs, they will have to be pruned off several times each season.

A gardener who prefers medium or small shrubs with many stems should select a crape myrtle variety with that mature size. Topping off larger plants is termed crape murder, because nodules form at each cut and many weak twigs grow out from them (see more on this in Pruning Crape Myrtles).

Limbs that cross over other limbs should be pruned, and seedpods can also be cut after the flower petals fall. Last week, I started pruning seedpods when I noticed new growth with flower buds under them. Apparently, I was wasting my time! When it comes to flowering, moisture and soil fertility are more important than pruning.

So choose a crape myrtle plant carefully and allow it to develop to its natural, genetically-determined size and shape. It will end up being much healthier and easier to maintain.

Pruning Young Plants

  • Most pruning is done in the winter.
  • Study branches before pruning.
  • Establish strong framework.
  • Prune for safety whenever needed.
  • Remove thin twigs and stems from base and lower trunk.
  • Head back stem tips to thicker, living wood.
  • Cut back to just above outward pointing bud.
  • Thin out branches at their tips.
  • Remove seed balls from younger plants.
  • Remove branches that grow inward toward plant's center.
  • Remove one of pair of rubbing branches.
  • Remove damaged or dead wood at any time.

Pruning Mature Plants

  • Remove excess branches near base, twiggy growth, crossing or rubbing branches and branches growing inward.
  • Thin and rejuvenate canopy of flowering wood.

Pests & Disease

  • Powdery mildew, a gray mold which appears on the surface of the leaves, is best controlled using mildew-resistance varieties of crape myrtle.
  • Aphids (very small soft-bodies insects) suck sap out of leaves and weaken plants.
  • Aphids excrete sticky honeydew which accumulates on surface of leaves
  • and results in sooty mold (black mold that looks like soot) on the leaf surfaces.
  • Control sooty mold by controlling aphids.
  • Control aphids with biological controls or approved insecticides.
  • Many gardeners choose to ignore aphids and mildew. Most plants will survive without treatment.
  • Remove aggressive vines that shade and weaken the canopy.

More on Crape Myrtles

Dr. Elmer Krehbiel is the former President of Keep Brazos Beautiful. See his column in The Eagle.