Why are my crape myrtle trees not blooming this summer?

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Question Why are my crape myrtle trees not blooming this summer?

Answer I have also had folks asking why their crape myrtles are blooming better this summer than usual. Ironically, these two questions are related. The “Easter Freeze” of ‘07 had a lot of influence on most crape myrtles. This freeze was a staggering blow, but if your crape myrtles aren’t blooming yet, then they were also hit with a second punch.

These trees have a tendency to sprout new growth early in the spring. They respond well to 4 or 5 days of early warm weather. On the other hand, that same new growth does not respond well to freezing weather. The tender new growth is typically killed back and another surge of new growth pops out when the next warm spell sets in.

At first glance this may seem to be a counter productive way of existing. However, crape myrtles bloom only on the current year’s new growth. Whenever a shoot is pruned by frost (or a pair of loppers), several new shoots are pushed into action. Therefore, a pruned crape myrtle branch will have more new growth than an unpruned branch. It appears as if crape myrtle trees use the last couple spring frosts to help reproduce (since more branches equals more flowers and more flowers equals more seeds).

Crape myrtles don’t get hit by a late frost every year. So you can’t count on nature to do your maintenance each year. The last freeze this year was worse than usual. It killed the tender new growth and some of last year’s dormant wood. Crape myrtle trees are survivors. Most of them eventually popped back out and started all over again.

Since April, some landscapes were hit with a second punch – the drought. A select group of blessed folks have gotten rain and other homeowners may have irrigation. The remainder of poor souls have crape myrtles without blooms. Water and fertilizer are the keys to recovery from a late frost.

Keep in mind the pruning of a crape myrtle tree should be very similar to the zapping it would get from a late frost. Excessive whacking of a tree will produce more blooms, but it ruins the natural shape and causes weakly attached limbs. Visit this site for a funny diatribe on the incorrect pruning of crape myrtles - http://plantanswers.tamu.edu/publications/stopthecrape.html

For more information about crape myrtle trees, check out http://pubs.caes.uga.edu/caespubs/pubcd/L331.htm If you don’t have internet access, then call 910-893-7533 or email me at gpierce@harnett.org

Andre Michaux was a French botanist who traveled to the United States. He was looking for new species of trees to use in the reforestation of France. The French forests had been destroyed by the demand for timber caused by the ongoing war with England. When visiting Charleston, South Carolina, Andre introduced a few new plants to the very young United States. These plants included the crape myrtle, mimosa (looks French) and camellia. The camellia introductions included the ornamental and tea types. The tea was either the French way of preventing another Boston Tea Party or a consolation prize for an eight year Revolutionary War. Who would have thought crape myrtles should be another part of our 4th of July celebrations?

Gary L. Pierce

Horticulture Agent

Harnett County