How to prune your crape myrtle this spring to produce more blooms and a healthier tree.
Crape myrtles (Lagerstroemia indica and cvs., USDA Hardiness Zones 7–9) are one of the most popular flowering trees in the country due to their manageable size and summer color. Crape myrtles can thrive in heat and humidity while also being drought tolerant and deer resistant. With winter protection, they can also grow as far north as zone 5.
Many homeowners plant crape myrtles, but very few people prune them correctly. Pruning improves the shape of the tree, increases the number of blooms, and flowers arrive earlier than do those on unpruned or mispruned plants.
Crape myrtles bloom on new growth, so they are best pruned in early spring before they come out of dormancy. Fall pruning not only creates an unattractive, barren look for winter, but also removes the current growth that the tree uses as a buffer to protect the main branches from winter damage. Effective pruning while crape myrtles are young will mean less maintenance and stronger trees when they are older.
Work from the bottom up
The growth habit of crape myrtles is typically to produce multiple trunks. This can cause the tree to become crowded as it matures. A healthy crape myrtle should have only a few main trunks, 3 or 5 is common. Removing the unnecessary ones early on will reduce the amount of pruning you need to do in the long run.
Maintain Structure For most crape myrtles, choose three or five main trunks. An odd number of trunks is more pleasing to the eye than an even number. Keep trunks that have ample space to grow and are growing straight and strong.
Suckers and additional trunks should be cut back as close to the soil line or notch as possible. This lessens the chance of a dead stub, which is a potential entry point for insects and diseases.
A well-pruned tree except for the suckers at the bottom
Most landscapers like the branching to begin 6 to 8 feet off the ground because it not only looks better, but it makes it easier to maintain the ground around the base of the tree. This is not necessary, if you’d like a more natural look and you don’t need to walk under the branches or see through the plant, you can allow the branching to start lower. Prune unwanted low branches all the way back to the main trunk.
A mature tree with no suckers or lower branches
Finish the top
Once you’ve removed the unwanted trunks, you will have also gotten rid of many of the upper branches. Check the remaining branches and thin the crown to improve the tree’s looks and health.
The upper branches look best if they are spread uniformly around the tree, so remove any that are growing close to other, stronger branches. Also look for branches that are parallel as this creates an unattractive look. Make your cuts slightly above a bud that faces the direction in which you want your new branch to grow, make sure that you do not leave any branches growing in towards the center of the tree. Remove limbs that cross back through the plant or rub against each other. Rubbing branches will wound each other, and can cause the one or both branches to die.
Keep the interior of the plant open to promote air circulation and allow sunlight to enter.
Finally, remove any branches or stems smaller in diameter than a pencil. Leaving this wood on the tree results in weak new growth, fewer flowers, and will cause them to arch downward if there are any flowers.
Poor PruningCrape myrtles are resilient and can tolerate the topping or shearing that some gardeners rely on. While they will survive this treatment, there are a few reasons not to prune them in this way.
Weak StructureSevere pruning encourages rapid new growth and large flower heads, but the new branches are too long and weak that they can’t support the weight of the flowers. Branches can easily snap off under the weight.
Fewer BloomsAllowing too many trunks to grow or cutting the plants back too far will result in a shrub-like plant with dense foliage that produces fewer, later blooms. This type of pruning will also promote powdery mildew which can weaken and kill the plant.
BarkCrape myrtle bark that is allowed to develop will result in a colorful, peeling bark similar to birch. This creates a focal point in the winter landscape as much as the flowers do in summer. (See the picture above and look at the back)