Do crepe myrtles actually need pruning to bloom?
No. This is the misunderstanding behind almost every butchered crepe myrtle in Georgia.
UGA Extension is blunt about it: the belief that these trees must be pruned in order to flower is false, and the most attractive crepe myrtles are the ones pruned lightly or not at all.
They bloom on new growth, which is where the confusion starts. People see flowers after a hard cut and conclude the cut caused them. The tree would have bloomed anyway.
What is crepe murder and why does it matter?
Crepe murder is the practice of cutting every stem back to the same height each winter, leaving a row of stubs that thicken over the years into knobbly fists.
What grows back from those knuckles is a spray of long, thin, whippy shoots. They are weakly attached, and they carry heavy flower clusters that bend them over in summer rain until the whole tree looks like it is collapsing.
The damage is not only cosmetic. Repeated heavy cutting shortens the life of the tree, and every large wound is an opening. UGA specifically flags that over-pruned crepe myrtles are more exposed to lethal insects such as ambrosia beetles and to disease.
And the shape does not come back. Those knuckles are permanent, and the natural vase form with smooth peeling bark, which is the best thing about the plant, is gone for good.
When should you prune a crepe myrtle?
Late winter, while the tree is still dormant and before the buds break. In Northwest Georgia that usually means February into early March.
Pruning in fall is a mistake, because it can push tender growth that a hard freeze then kills. Pruning in summer costs you the bloom.
How should a crepe myrtle actually be pruned?
Think of it as editing rather than cutting back. In rough order:
- Take the suckers off the base. These sap energy and ruin the form.
- Remove crossing and rubbing branches inside the canopy, along with anything dead.
- Lift the lower limbs gradually over a few years if you want to see the trunks, which is the whole reason to grow these as small trees.
- Thin, do not top. Where the canopy is congested, remove a whole branch back to its origin rather than shortening everything.
- Leave the seed heads alone if you like. Cutting them off is optional and makes no real difference to the tree.
The rule of thumb that keeps people out of trouble: if you are about to cut something thicker than a pencil, stop and ask why.
Why is my crepe myrtle turning black?
Almost certainly sooty mold, and the mold is a symptom rather than the problem.
The usual cause in Georgia now is crape myrtle bark scale, an insect from Asia that was first confirmed in the state in Coweta County in 2014 and has been spreading since. It feeds on the tree and excretes honeydew, and sooty mold grows on the honeydew and blackens the trunk and branches.
Other signs worth checking for are ants and wasps working the trunk to collect the honeydew, leafing out late in spring, smaller bloom clusters than the tree used to make, and a general loss of vigor. On close inspection the scale itself shows as small white or gray felted bumps on the bark that smear pink if you crush one.
Worth being straight about scope here: we are a tree service, not a pest control company, and we do not spray or inject. What we can do is tell you what you are looking at and deal with the tree if it has gone too far. Treatment is a licensed pesticide applicator's job.
Can a topped crepe myrtle be fixed?
Improved, yes. Restored to what it would have been, no.
The approach is patient. Over several winters, select the strongest one or two shoots coming off each knuckle and remove the rest, so the tree gradually rebuilds something like a branch structure instead of a broom. It takes three to five years and the knuckles stay visible.
Where a crepe myrtle has been topped for a decade and is mostly knuckle, the honest answer is sometimes to take it out and plant one that will be left alone. If it comes to that, it is a small job, and our tree removal page covers how removals are quoted.