No one knows exactly how or why southerners began whacking their crape myrtles, but it's been a real struggle to get the practice stopped.
Some will contend that it makes the plants flower better, but research and experience have shown that that's simply not true. Topping actually delays their blooming by weeks or months, and the flower heads that do form are so large that they aren't held erect. Ugly, ugly, ugly!
Some say it's because their plant has gotten too big, but that just points to a bad variety choice initially. Those plants should either be relocated to more spacious surroundings, or they should be removed altogether. Topping just delays the inevitable. There are plenty of other varieties of crape myrtles that will be smaller at maturity. Use one of them.
So, what do you do if you have a plant that someone else chopped before you? Can it be saved? Well, yes, but it's a radical solution. Cut the plant back flush with the ground. Dozens of new stems will emerge, and all you have to do is retrain some of them to be the new trunks. You'll have a beautiful crape myrtle within just a couple of years. Without that remedy, you'll be looking at scars and gnarls almost forever.
Help us spread the word, won't you! Topping is barbaric.