By Lori Murray, Cameron County Master Gardener, Texas Superstar Specialist
Crape Myrtle Information
Crape Myrtles require well drained soil that ranges from slightly alkaline to slightly acidic, so where your soil is ranked on the pH scale determines what actions you need to take. The process of determining that ranking is pretty complicated, but fortunately all you have to understand is what the numbers mean, not how they are derived. The number seven is neutral and is the pH of pure water.
Soils with a pH less than 7 are acidic while those with a number greater than 7 are alkaline. A few other numbers, just to give you the general idea: Acidic – orange juice has a pH of 3, tomato juice is 4, and black coffee and bananas have a pH of 5. Alkaline – Sea water and eggs have a pH of 8 and baking soda would be a 9. That’s why an annual application of compost is useful and also why some old-timers used to put banana peels in their rose beds: they were turning their alkaline soil slightly acidic to promote bloom.
Mildew can be a problem in our humid climate. Fortunately, botanists have created crape myrtle hybrids to combat those problems. Nevertheless, that possibility is why good air circulation is so important to both crape myrtles and roses. Varieties with Native American names such as Arapaho, Hopi, or Natchez are especially resistant. In addition to deep but infrequent watering and nearly full sun, the Crape Myrtles require pruning to promote the growth needed for blooming, to reveal the bark, and to keep the shrub or tree tidy.
Also, with its flowers, leaves, and peeling bark, a crape myrtle can be messy to care for. Keep the clean-up in mind when you choose your location. Also, Victoria Weinblatt of Demand Media suggests that to thwart Texas root rot you would want to plant “Cherokee” or “Catawba” (Lagerstroemia indica). Both these varieties grow 25 feet tall at a rate of 24 inches per season, so be sure you have the space for them.
While some authors maintained that you would only have to do minor pruning if you select the right crape myrtle for the space where it will grow, others spent considerable time discussing the how-to of this option. All of them emphasized that the blooms come on new growth and that pruning, if you do it, should be done early in the spring – like February. They agreed that you could remove small twiggy branches inside the plant at any time to promote good circulation. An option if you want it to be a small tree is to gradually remove lower branches or suckers that grow from the base of the plant.
In the case of a neglected older plant, a heavier hand could be used: remove any dead branches and cut back the living branches slightly to promote more vigorous growth (just don’t expect flowers that season). One warning was that larger, heavier flower clusters and rank growth often result when the branches are cut back severely, and that the flowers are often so heavy that they bend the branches to the ground. For that reason, cutting the plant to the ground every year is discouraged. Other than these divergent views, the general standard rules of pruning apply (but space prohibits including them in this discussion.)
Choosing the best for you
When selecting a crape myrtle, think about the flower color and ultimate size first. How do you want to feature the plant in your yard? Will it be a focal point? A grouping? A privacy hedge? How can you know what variety you want? Although the Crapemyrtle Quick Guide Chart is no longer available from the National Arboretum through the USDA, Southern Living has a pretty good guide as do several other sites. (Google Crapemyrtleguides) As always, it’s also a good idea to consult with a nursery specialist like someone at Grimsell’s to get the latest practical advice.