Pruning and Fertilizing Crape Myrtles

Henry Harrison  |  2/4/2006 12:38:54 AM

February is a good time to prune those crape myrtles, and if you have been getting NO BLOOMS OR POOR QUALITY OF BLOOMS, fertilizing just may be the answer. Use 8-8-8 or 13-13-13.

One of the best features of crape myrtles is the natural growth habit. Frequently, improper pruning destroys this desirable aspect. Use a selective method of pruning (thinning out the plant canopy) to achieve the best growth habit.

For tree form specimens, remove all suckers at the base of the plant each winter. It is a must to retain all the major trunks. Also remove any weak, crowded limbs in the center of the plant canopy to provide an open growth habit that allows air circulation and sunlight penetration.

A unique characteristic of many new crape myrtle varieties is the trunk. It frequently has excellent color and exfoliating (peeling) bark. Prune to enhance these features.

Pruning of bloom clusters when flowers fade may produce additional and prolonged flowering. This is time consuming. It may be practical for homeowners, but it’s not commercially justifiable for landscape professionals. Also, heavy bloom clusters produced on vigorous shoots resulting from excessive spring growth can make a plant top-heavy and cause limbs to break. Pruning of these bloom clusters can protect the plant form and growth habit.

Failure to Flower: One of the problems occasionally encountered by homeowners is the lack of flowers. Possible reasons for lack of flowering include:

  • Excessive shade. Crape myrtles require 8 hours of full sun daily for optimum flowering.

  • Variety. Some varieties don’t flower as vigorously as others.

  • Heavy aphid infestation. Aphids are common insect feeders on crape myrtles and can decrease flowering.

  • Lack of fertilization. Crape myrtles require fertilization for new growth. If new growth doesn’t occur in the spring (because of nutrient depletion or cold weather), flowering may be greatly reduced.

  • Improper pruning. Drastic pruning or pruning after new growth in the spring can delay summer flowering. Drastic pruning may promote excessive growth and less flowering.

  • Over-fertilization. Excessive fertilization in conjunction with other factors, primarily improper pruning, can eliminate or delay flowering.

  • Leaf spot. Foliar diseases decrease plant vigor and flowering, especially where new growth is not produced in the spring.
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