Q: How am I supposed to prune a crape myrtle?
Answer: That’s a frequent, controversial and good question! The term “crape murder” came about because of the heavy pruning performed on some trees.
Let’s start with why we prune. Some people don’t like the way crape myrtles look in the winter — barren, leggy and misshapen.
We prune to change the shape, size and/or appearance of a plant. We can prune to remove pests or disease and improve the structure of the plant. Pruning stimulates flowering, is used to remove branches that are dead or damaged and can redirect growth away from structures.
In the past and prior to the sale of disease-resistant crape myrtle cultivars, people thinned out the interior branches because it afforded better air movement, which dried the leaves and decreased the presence of powdery mildew disease. This pruning procedure is not necessary today.
If pruning is necessary, the procedures recommended are tipping and pollarding. Tipping, also known as tip or pencil pruning, is so called because the cuts are the diameter of a pencil. This is a time-consuming process that results in a very attractive tree. Some people tip prune to remove the seed capsules, but it is not a needed maintenance activity and is aesthetic in nature. This pruning method doesn’t significantly impact plant health.
The time it takes for this type of pruning increases annually.
Topping is not recommended and involves removal of large-diameter limbs, which shortens all of the stems and branches. Topping decreases the tree’s canopy and ability to produce food, weakens the structure, and increases access by insects and wood-rotting organisms. This method takes the least amount of time to perform and requires the least amount of skill; however, it delays flowering and results in weak growth and increased sprouting.
The photo with this article is of a topped crape myrtle tree in my neighborhood.
Pollarding is cutting through branches that are less than three years old, then sprouts are cut back to the original cut on an annual basis. This allows for maintaining smaller-size trees. Using the pollarding process results in a “pollard head,” which is a swollen area. Pollarding increases the amount of maintenance needed on a low-maintenance tree and results in fewer dead branch stubs and internal wood decay than topping.
This type of pruning takes more time than topping, though, because a larger number of pruning cuts are needed. Pollarding and topping delay crape myrtle flowering for one month and shorten the bloom season on some cultivars. These pruning techniques also increase root, stem and upper base sprouting, which increases maintenance as the sprouts need to be removed.
A crape myrtle should be planted in full sun, away from walkways and where it has sufficient room in which to grow. This tree is low maintenance and needs minimal to no pruning. The more severe the pruning, the fewer number of flowers will bloom. The amount of yard waste increases as pruning activities increase.
Many times people select cultivars that are not appropriate for their zone or planting location. If pruning is necessary, follow the recommendations made by Gary W. Knox and Edward F. Gilman in their University of Florida publication “Crapemyrtle Pruning,” from which this article was adapted. You can read it in its entirety at http://edis.ifas.ufl.edu/pdf files/EP/EP39900.pdf. When you access this article, you will be able to view each of the pruning technique results.
Lynn Barber is the Florida Yards and Neighborhoods agent at Hillsborough Extension. Reach her at BarberL@hillsboroughcounty.org.