This year is looking like it’s going to be a beautiful year for crape myrtles. Early types are already stunning and the later varieties are filling with buds. It might be a good time to throw out some facts to amuse you. These are things you may not have known about this wonderful plant.
Most of our older varieties of crape myrtles are from the species Lagerstroemia indica. (My facts will get more interesting, but this was a good starting point.) The specific epithet “indica” means native to India, but that was a mistake. These plants are actually native to China. Therefore, they rightfully should have been named Lagerstroemia sinensis (indicative of China).
All crape myrtles are genetically shrubs. In fact, it wasn’t until the 1960s that landscape architects began to specify that lower branches and trunks be thinned and removed to turn tall shrubs into small accent trees.
Until the 1960s not much attention was paid to variety names. You just went into the nursery and bought your crape myrtle by color: red, pink, white, purple or lavender. But that was a dreadful criterion because crape myrtles come in all sizes. You never knew what you were getting.
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It was during that same time period that Dr. Don Egolf of the United States National Arboretum in Washington D.C. brought cuttings of another species of crape myrtle, L. fauriei, from Japan. It has superior bark color (cinnamon-red) and almost complete resistance to powdery mildew, long the foe of the older varieties.
Dr. Egolf used this second species in his incredible breeding program. He evaluated 200,000 seedlings in test plots across America, including where I was working at the Texas A&M Center on Coit Road in Dallas. I watched many times as he and Benny Simpson evaluated the seedlings. Those that offered nothing special were discarded. Eventually Dr. Egolf introduced 29 varieties, all bearing the names of Native American Indian tribes in recognition of Don’s native state of Oklahoma.
At this time there are some 130-140 named varieties of crape myrtles that we have been able to locate and track. They vary in height from 2 to 32 ft. tall, so there’s a crape myrtle for almost any space.
Crape myrtles vary considerably in winter hardiness. Some types such as the miniature weeping selections with Louisiana names (Baton Rouge, Lafayette, New Orleans, etc.), also Natchez, Muskogee, Sioux, Tuscarora and Country Red have frozen repeatedly in North Texas winters. Most others are reliably winter-hardy clear into Oklahoma and even Kansas.
If you have a crape myrtle that is too large for the place where it has been planted, do not “top” it. Either move it or remove it. Transplant it to a place where it can grow unimpeded or take it out entirely. Trying to control size by pruning is absolutely futile. Each variety is genetically predisposed to grow to a certain mature size whether you whack it or not. In the meantime, the barbaric act of topping crape myrtles delays their summer blooms by six to eight weeks and it ruins their shape forever.
There is no need to remove spent flower heads from plants during the season. Crape myrtles usually produce two or three rounds of flowers starting in June and continuing well into September, and removing seed heads does not speed up the next generation of flowers at all. And by the same token, you don’t need to clip off the dried fruit capsules in the winter. Crape myrtles, being sub-tropical plants, will always die back a few inches as new growth comes out in the spring. Those seed heads and small twigs will fall to the ground in May as the strong new growth begins.
If you buy a house where a crape myrtle has been topped, and if you wish it could have a nice, normal growth form, rather than trying to nurse it back to good shape by pruning year after year, cut it completely back to the ground instead. It will send up straight new shoots that can easily be trained into new trunks. Your only challenge will be to select which trunks you want to leave. Otherwise you’ll be amazed at how quickly it will respond. You’ll have a beautiful crape myrtle within just a couple of years.
In 2004 a new pest for crape myrtles in America came onto the scene. It actually showed up first right here in the Metroplex. Crape myrtle scales were brought into a nursery in southern Collin County by a homeowner. They look like pieces of white perlite or popcorn stuck to the trunks. By 2007 they had spread across much of the Metroplex and now they’re spreading across the South. In recent years they’ve been identified as a pest native to China that has now made its way to our country. They exude a sticky honeydew, and sooty mold will develop within that honeydew substrate. Most years the scale insects aren’t very serious. When they are, they don’t do much damage, but they’re ugly and very annoying.
To keep crape myrtle scale under control apply Imidacloprid systemic insecticide as a soil drench in mid-to-late May (or now). If you see a heavy population of black ladybugs with two orange dots on their wings, those are predators to the scales. Forgo the insecticide long enough to see if they will control the scales.