
Most-Asked Crape Myrtle Questions
Neil Sperry
Horticulturist and Board Member
The Crape Myrtle Trails of McKinney
You will find answers to most crape myrtle questions in detail in other listings within this site. However, as a quick reference, here are the most common questions pertaining to this great group of shrubs and trees.
Before we registered the name of The Crape Myrtle Trails of McKinney, we did extensive research on what the correct spelling should be. We consulted with plant taxonomists at leading agricultural universities, the U.S. National Arboretum (where massive research on the plant had been done), with noted authors and growers, also with historical literature.
Based on all that, we discovered that only the scientific name must be assigned precisely. The genus involved is Lagerstroemia. The first species to be brought into common cultivation in the United States was Lagerstroemia indica. Those are names that must be used intact.
But beyond that, common names can be spelled in a multitude of ways. We looked at 20 of the most influential horticultural reference books in America at the time of our organization’s founding, and 17 of them spelled the plant’s name as “crape” and used two words (“crape myrtle”). Two used “crepe” and one used “crepemyrtle.” We registered with the common name used by the majority.
Buy only named and labeled crape myrtles. It is the only way you can be sure of what you are buying. Your first decision needs to be mature plant size. It’s sad to see someone invest time, hope and money in a crape myrtle, only to find, years down the road, that they have chosen a plant whose genetic potential will ensure that it will be too tall, too wide or too short for their needs. Flower color is the next consideration, and, close behind, would be disease resistance.
Container-grown plants come with all of their roots intact, so they will establish and grow most quickly. Balled-and-burlapped plants are often available in larger sizes for more dramatic landscaping appearance. Let your nursery employee suggest the best plants for your needs, or consult our list of varieties.
Crape myrtles need full sun and average garden soils. Avoid sites that get less than 6 to 8 hours of sunlight daily, also those that have shallow, rocky soils. Tall crape myrtles can be used as patio and entryway trees, along drives and walks and as tall, deciduous, screening shrubs along property lines. Medium-sized types work well in front of taller evergreens, also as anchoring shrubs for free-standing perennial gardens. Dwarf crape myrtles can be massed in beds almost as one would use taller perennials. Miniature, weeping crape myrtles are used in pots, hanging baskets and bed edgings. There are crape myrtles for all uses, so long as the requirements for good soil and ample sun are addressed.
If you’re unsure of the specific color you might want, buy your crape myrtles during the summer, while plants in nurseries are in full bloom. However, be prepared to water your new plants by hand every couple of days to prevent their getting too dry. Container-grown crape myrtles are traditionally produced in lightweight potting soils that do not retain water for very long at high temperatures. By the second summer, you can generally rely on your lawn irrigation to be adequate. If, however, you are sure of the labeling at your favorite nursery, October is the single best time to plant most woody plants, crape myrtles included. If, on the other hand, you are actually digging an established crape myrtle, the best time to do so is during the winter dormant period, generally between Thanksgiving and the end of February.
Be very careful. Probably 98 percent of the pruning Texans do to their crape myrtles is done incorrectly. Never “top” a crape myrtle! Do not use pruning as a means of controlling crape myrtles’ height. If a variety is growing too tall for its location, move it and choose a shorter type. See information on topping and pruning of crape myrtles.
This answer may surprise you, but the fastest way of getting an attractive plant back is simply to cut all the trunks completely to the ground, then manage the new shoots that come back. You will have your choice of dozens of new trunks. Select those few that are most vigorous and most appropriately placed, then remove all the others. Because all of the plants’ roots will be supporting the small amount of top growth initially, the new shoots will force out in a hurry. You will probably have attractive plants that same year. You certainly will by the second year. If you were to opt to try to re-form the plants by pruning the old, stubby shoots, it might take you 10 or 15 years to get them to grow out of it. See example of retraining a crape myrtle that had previously been topped.
All crape myrtles are genetically shrubs. Landscapers discovered, somewhere back in the 1950s, that we could remove side shoots and some of the trunks and train the taller types to grow as small accent trees. That was perfect, because that was also the time that our landscapes were becoming smaller and smaller.
Crape myrtles bloom on their new growth, so you will want to apply a high-nitrogen, lawn-type fertilizer (no weed killers included). The first application should be made in mid-April as the plants are starting to grow most actively. Repeat the application in mid-June for sustained feeding all summer. Apply one pound of fertilizer per cumulative inch of trunk diameter. Add the several trunks together to determine the total needed.
This is a common concern of envious gardeners. It can be nothing more than a varietal difference. Some crape myrtles come into bloom in May, while other varieties wait until July or later. It can also be due to your pruning practices. People who prune their crape myrtles heavily over the winter (especially those people who mistakenly “top” their plants) will often cause them to bloom 4 to 8 weeks later than they would had they not been pruned. Also, if crape myrtles don’t receive enough sun they may be reluctant to bloom.
This is absolutely and totally a normal occurrence. Crape myrtles have exfoliating bark. It peels off in long hunks, often exposing glossy, honey-colored trunks. Some of the U.S.D.A. introductions such as Natchez have beautiful cinnamon-colored bark. In all cases, the peeling bark is completely harmless.
That is the fungal disease called powdery mildew. It most commonly attacks young leaves, shoots and flower buds in spring and early summer, generally shutting down once daytimes go into the 90s. Our list of recommended varieties takes resistance to powdery mildew into consideration. Plant your crape myrtles in full sun and where air circulation is excellent. Apply a labeled fungicide as needed to stop it.
That is honeydew being secreted by crape myrtle aphids or scale insects. For aphids, look closely at the newest leaves and you will see the small, pear-shaped pests congregating. Scale insects are white pests that adhere to the trunks and branches. Systemic insecticides such as Imidacloprid applied in mid-May offer the best preventive control. Left unchecked, either pest can secrete enough honeydew to coat the leaves completely. Black sooty mold will grow in the sticky layer, disfiguring the leaves and even causing premature defoliation in late September or October. However, the mold is not especially harmful, and most of it will slough off with the old bark the following spring.
Since crape myrtles are hybrid plants, they will not “come true” from seeds. Probably one plant in several thousand would be of quality enough to keep. Nurserymen start new crape myrtles by taking cuttings either in late winter (hardwood cuttings) or in May (softwood cuttings). See the discussion on crape myrtle propagation.
Crape myrtles, like yaupon hollies and even some live oaks, will throw out root sprouts. Left in place, they will create a thicket of crape myrtle plants. Assuming you do not want that, you should dig and remove them using a sharpshooter spade. The entire process probably won’t take more than a few minutes each year. You cannot spray them, since they are tethered to the mother plants. Since crape myrtles are propagated by cuttings, their root systems are the same as the top growth, so these sprouts can be used as a means of starting new and identical plants.