It is a sure sign that pruning season has begun when I start noticing crape myrtles with their heads lopped off.
Many garden writers and Extension people call this "crape murder," and it has become so common in commercial landscapes that many homeowners are convinced it is the correct way to prune their crape myrtles.
Before I provide you with some tips on how to prune correctly, I am going to go over a few of the most common misconceptions and comments I get when folks call into the office:
"But, if I don’t prune my tree, it won’t bloom."
Let’s get one thing straight: You absolutely do not have to prune crape myrtles to make them bloom.
As evidence, let me point out the most beautiful crape myrtle I have ever seen was one that was allowed to grow into a huge tree in front of my grandmother’s home in Montgomery, Alabama. For many years it was left untouched, yet it bloomed profusely every year.
"It’s just getting way too big."
If your tree is too tall or threatens the structural integrity of your home, then you have it in the wrong place. Pruning to reduce height will only start a maintenance war that you will never win.
The best approach is to consider the projected size of the mature plant before installing it into the landscape. Fortunately, there have been success stories of transplanting large crepe myrtles.
If you go this route, just be sure that you replace yours with a cultivar that best suits your landscape needs before planting.
If you select a tree that will not outgrow its boundaries, then it can display its graceful beauty with minimal pruning.
There are many new cultivars in different sizes and colors. The dwarf (3 to 6 feet) and semi-dwarf (5 to 15 feet) selections now available make it easy to choose the right size plant for a certain space.
Compact crape myrtles between 3 and 6 feet include "Hope" (white), "Ozark Spring" (lavender) and "Victor" (red). Unfortunately, the compact crape myrtles are not as resistant to powdery mildew, a white fungus that occurs on the tops of the leaves.
Crape myrtles that mature between 5 and 15 feet include "Acoma" (white flowers), "Hopi" (light pink), "Comanchee" (dark pink), "Zuni" (lavender) and "Tonto" (red). These are fairly resistant to powdery mildew.
"My neighbors pruned theirs."
Let me tell you this, improper pruning is a copycat crime. Each tree has a different form, and its role varies from one landscape to the next.
Therefore, you need to figure out why you are pruning before you ever cut a branch. After all, you can always go back and cut more, but you cannot go back and cut less.
Having said that, it is important to understand the reasons why we prune crape myrtles, which are to improve plant structure, eliminate plant defects and increase air circulation in the plant to reduce instance of disease.
Fortunately, crape myrtles are resilient plants and can take a punch better than anyone. Sometimes, I’m truly amazed by what some of these trees live through when pruning season comes around.
Now, let’s talk about how to execute the different pruning techniques and strategies correctly. To allow a young or newly planted crape myrtle to grow into a tree form, simply select 3-5 of the strongest, healthiest stems — these will become the trunks or major scaffold branches.
You also need to consider the location of the plant. If your crape myrtle is in a large bed, then you may want to save the widely spaced stems to create a wide, natural sprawling effect. If the space is limited or visibility under the plant is important, then I suggest selecting more upright stems as you main scaffold branches.
Remove all of the other stems and suckers at the base of the plant. Next, remove the side shoots a third to half up these stems. This raises the canopy of the plant.
You can follow those steps for more mature trees too, but if the crape myrtles are near a driveway or street, I like to raise the canopy a little closer to half the plant height so that it creates less visual obstruction to drivers.
As in most pruning, remove diseased, damaged and inward growing branches. Also remove branches that cross or rub.
If the plant growth is extremely dense, then you can thin the canopy, keeping in mind that the goal is cutting to see through them, not over them.
Use this phrase as a guide: "If a bird can easily fly through the center of your crepe myrtle, then the branches are spaced about right."
For aesthetic reasons many folks also remove the spent seedheads but it is not necessary. If seedheads are out of reach just let them go.
It is easy to get overwhelmed when pruning, especially if you lack experience. My advice is to go slowly and take the time to step back and look at your progress as you go.
Remove limbs from the inside of the tree, especially limbs that cross or hang so low that they hit you in the face. Remove entire limbs flush with the trunk but take care to not cut into the branch collar.
If you leave a large stub, then four or five new shoots will grow in place of the one you removed.
For most of us, I think it pays to spend a little extra time and prune our crape myrtles to a more natural form. I believe they set buds more quickly in the spring and the overall appearance is much better.