Pruning Crape Myrtles

The crape myrtle (Lagerstroemeria indica) is one of the most beautiful and popular flowering trees of southern landscapes. Crape myrtles have endured a great deal of harassment over the years by well-meaning landscape crews and home owners. They, it seems, have been under the false impression that crape myrtles must be severely pruned each winter. This pruning involves cutting the tops out of the subject trees (topping) in order to shape them or, more importantly, restrict their height. This practice often results in a “witch’s broom” appearance.

Topping causes wild and profuse growth at the site of the pruning, thus encouraging new growth that is too dense to allow air and light to reach the inner branches, resulting in greater potential for foliar diseases and insect damage. Large ugly “knobs” appear where trees have been pruned repeatedly. Although topping may result in larger blooms, there will be fewer of them, and those flowers will grow on thinner, weaker branches that will droop and even break-especially after a rain.

So, why do we need to prune crape myrtles anyway? The major purpose of any pruning is to create a canopy in which air can circulate and all branches can receive maximum sunlight. This should be done in mid-winter (January and February) when the trees are dormant. Other pruning objectives include maintaining the crape myrtle’s natural sculptural form and producing strong branches that hold flowers upright.

How do we correctly prune crape myrtles? Here are some basic pruning practices to follow when pruning crape myrtles and, for that matter, any other tree or shrub.

•Remove branches which may be crossing or rubbing one another. If both branches are pointing outward (as they should), remove the weaker of the two limbs. Remove any branches which point inward toward the center of the plant.

•Remove all inferior, damaged, or diseased branches.

•Remove all suckers from the base of the tree at ground level.

•Thin out small, twiggy growth to allow better air circulation and the entrance of sunlight into the canopy.

If you have a young crape myrtle tree remove all side branches growing off the main trunk up to a height of five feet or whatever height is pleasing to you. Cut off any old seed heads if desired. This is an unnecessary practice but will help, if done in July and August, to promote additional flowers. To be sure, your crapes will bloom just fine each year whether or not you prune or deadhead them.

For a severely damaged tree (one with the characteristic “knotty’ appearance where it has been trimmed year after year), cut it back to within two inches of the ground with a chain saw. March is a good time to do this. The tree will promptly put out new and vigorous growth as soon as spring temperatures rise and will quickly grow to two or three feet. At this point, select three to five of the best shoots to keep as future trunks and remove the rest of them. Hereafter, simply remove all the side branches from these shoots. Never remove any top growth.

If your crape myrtle has not been so drastically butchered and looks something like a hat rack (without the knottiness described above), it is not necessary to cut it to the ground. When the tree puts out its cluster of branches from being topped, simply remove most of the branches, selecting only one or two new shoots from each stub to remain. This will encourage the remaining branches to be stronger and the canopy of the tree to be airier and should improve the health and appearance of the tree.

Here are some additional thoughts on crape myrtles. If you want a crape myrtle that is only six feet tall you do not achieve this by cutting out the tops year after year! The answer is to choose the proper sized tree for the space. Unbeknownst to some people, there are varieties of crapes that grow from 18 inches to 30 feet. These are known as dwarf, semi-dwarf, medium, and full-sized.

Enjoy your properly pruned crape myrtles!

Tim Lewis is a Georgia Green Industry Association Certified Plant Professional, gardening writer, former Perry High School horticulture instructor, and former horticulturalist at Henderson Village and Houston Springs. He and his wife, Susan, own and operate Lewis Farms Nursery located on Hwy 26 two miles east of Elko, where he was born and raised. He can be reached at (478)954-1507, timlewis1@windstream.net, and LewisFarmsNursery.com.