You see it every year in the spring, Crepe Murder. What is it, why do people do it and how can you repair the damage?
Crepe Myrtles bloom on new wood. New wood is the growth that comes out each spring and summer. The reason many people hack off the tops of crepe myrtles is they think it will increase the amount of new growth and number of blooms.
Why Not Top Crepe Myrtles:
Reduced photosynthesis: Topping any tree results in the removal of much of the tree’s canopy of leaves making it extremely difficult for tree is to take in enough nutrients through photosynthesis. The tree becomes weakened and starved for food.
Weak limbs: The tree struggles to survive by attempting to grow new shoots and leaves as quickly as possible. This causes numerous weak limbs to sprout around the wounded areas. Not only are these limbs unsightly and poorly attached to the stubs, they grow very quickly as the tree attempts to replace its canopy of leaves, thereby negating the original goal of making the tree have increased blooms. In essence, the attempt backfires, with the tree regaining much of its original height, but doing so with weaker branches that pose more or a danger than the original growth.
Sunburn: The tree itself and the plant material under the Crepe Myrtles are now in full sun. While it may seem odd to think of a tree being harmed by the sun, the sudden exposure of previously shaded bark may damage underlying tissue. If the tree previously provided cover for shade loving plants like azaleas, those plants may be damaged or destroyed by the sudden exposure to direct sunlight. If the tree or the vegetation beneath it dies, the homeowner may have to bear the costs of removal and/or replacement.
Ugliness factor: While all of these are good reasons not to top trees, there is one more, which I’ll just call the ugliness factor. Topping destroys the natural graceful structure of trees. It leaves them mangled and struggling. Instead of increasing the beauty of the landscape, topped trees detract from it. For those of us who value plants and nature, watching a mutilated tree suffer is simply painful.
Correcting the damage: You have two options for rehabilitating a “murdered” crepe myrtle.
The first method is to choose the strongest two or three sprouts from each stub and remove all of the other sprouts. This will encourage the remaining sprouts to be stronger and the canopy of the tree to be airier. If you follow this procedure for a couple of seasons, the tree is sure to be much improved in health and appearance.
The second–and more drastic–technique is to cut the tree back to within one to two inches of the ground while the tree is dormant. After two to three weeks of growth, select three to five of the most vigorous new shoots on each trunk and remove all others. Remove any new shoots that emerge later. Within three to five years, you will again have a natural-looking crepe myrtle.
Correct Pruning of Crepe Myrtles: When the tree planted and in the first few years of growth, the main goal of pruning should be to develop the main trunk structure with 4 to 5 trunks, build a vase like shape, remove crossing, broken branches, extra trunks or suckers, branches growing towards the center of the tree and dead limbs. Generally, prune crepe myrtles in the winter.
As the trees age, they should require less and less pruning. Remove all side branches up to 4 feet from the ground. A general rule of thumb when removing lower branches is to remove the lower 1/3 and leave the upper 2/3 of the branches. Crepe Myrtles are known for sprouting many suckers. Check with your garden center, there are products available to inhibit sucker growth. Follow these simple steps to protect the health and beauty of your crepe myrtle. No more Crepe Murder Please!!!
References: NCSU Burke Co Extension, ‘Crepe Murder Revisited’, University of Florida, IFAS Extension and Penn State Master Gardener articles on ‘Crepe Murder’