Crape Murder. What is it, why do people do it, and how can you repair the damage? The reason many people hack off the tops of crape myrtles is they think it will increase the amount of new growth and the number of blooms. Why Not Top Crape Myrtles? Reduced photosynthesis, that's why. Topping any tree results in the removal of much of the tree’s canopy making it difficult for the tree to take in enough nutrients through photosynthesis. The tree becomes weakened and starved for food. Also, the tree struggles to survive by attempting to grow new limbs and leaves as quickly as it can. Each cut place leaves an open womb for insects and disease to enter. It takes time for the limb to heal over. Some dead material will remain inside the tree forever underneath this healed area.
This causes numerous weak limbs to sprout around the wounded areas. Not only are these limbs unsightly and poorly attached to the stubs, but they also 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 of a danger than the original growth. Sunburn- the tree itself and the plant material under the crape 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 we will just call the ugliness factor. Topping destroys the natural beauty 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.
You have two options for saving a “murdered” crape 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 in late spring, 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 crape myrtle. Correct Pruning of Crape Myrtles: The goal of pruning should be to develop 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 crape myrtles in the winter. As the trees mature, 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. Crape myrtles are known for sprouting many suckers. Be sure to remove them as they will rob your tree of water and nutrients and make all of your pruning pointless.
Check out the short video below for a little more guidance on this subject. You can find more information at this link https://piedmontmastergardeners.org/article/how-to-prune-crape-myrtles/