Star Gardener: Not All Crape Myrtles Are Created Equal

The importance of protecting trees from the north and northwest with windbreaks
Hybrids named after Indian tribes, such as Hopi, are the crape myrtles most adaptable to the East End. Abby Jane Brody

It’s been readily apparent that some crape myrtles here were badly damaged by two brutal winters, while others escaped seemingly unscathed.    That raises questions. Which ones are most adaptable to the East End, and under what conditions?

Looking for answers, I sought out Dr. Margaret Pooler, research geneticist in charge of the crape myrtle (Lagerstroemia) hybridization program at the National Arboretum in Washington, D.C., and Jeff Rogers of Beaver Tree Nursery in Orient, who has grown them for more than 20 years. They agreed that the extended cold and accompanying desiccating winds are the primary problems.

Mr. Rogers pointed out the importance of protecting trees from the north and northwest with windbreaks, hedges, or even a building. The weather also may have contributed to this summer’s sporadic flowering. Oddly, some trees flowered earlier and some later than normal.

Shade definitely reduces flowering. Dr. Pooler said crape myrtles require at least six to eight hours a day of full sun. Over-fertilizing is another cause of reduced flowering, according to Mr. Rogers. As with other plants, too much fertilizer promotes foliage growth at the expense of flowers.

When selecting a planting site, good drainage is essential. While mature trees are said to be drought-resistant, Mr. Rogers said his trees began to bud up this year only after being well watered.

With these caveats, which are the crape myrtles that adapt most easily to the East End?

The simple answer is the hybrids named for Indian tribes, released by the National Arboretum breeding program. The cultivars mentioned most frequently are the tall tree-like Natchez (white), Muskogee (light lavender), Tuscarora (dark coral pink), Tuskegee (dark pink to red) and the semi-dwarf Acoma (white) and Hopi (clear pink). Catawba, which has purple flowers, is not a hybrid but a selection of the less hardy parent of the hybrids, L. indica. If that is the mature tree, and I expect it is, with the purple flowers I saw on the North Fork, it was protected from the north and northwest and was in pristine condition.

Dr. Pooler wouldn’t be pinned down about which of the 29 different crape myrtles from her breeding program would be our best performers. Unfortunately, she could not suggest any performance trials other than one at Louisiana State University, which would not be relevant for us. However, she said the arboretum is “reintroducing” Apalachee, a small upright tree with lavender flowers and cinnamon-to-chestnut-brown bark. “It has great bark,” she said, and a medium size.

The tall size of many crape myrtles has led to the custom of “crape murder,” as Dr. Pooler called it. Both she and Mr. Rogers railed against pruning the top off the trees. Unfortunately, this is not simply a bad Southern custom, but is also prevalent in our area, where too many landscapers don’t know any better. “If you have to prune it every year, you have the wrong tree,” Dr. Pooler said. The only reason to prune crape myrtles, they said, is to correct branch structure and remove dead wood.

The research program at the National Arboretum is focused on filling in the gaps in its releases, especially trees with “real” purple and red flowers in tall and smaller heights. One look at Catawba, and it’s easy to understand the search for purple-flowered hybrids. 

And unfortunately a survey of vivid red crape myrtles in our area turned up a real need for further breeding. Over the last few weeks I’ve sought out examples of the reds in particular, because of their popularity; they seem the most vulnerable of the crape myrtles to cold winter weather. Dynamite and Red Rocket and Pink Velour are three L. indica selections, made over a 25-year period by Dr. Carl Whitcomb of Oklahoma, that have been available at East End garden centers. Apparently they are not as cold-hardy here as they were thought to be. Most trees I saw were filled with dead branches, and, frankly, looked sad in spite of the gorgeous panicles of flowers. 

If you cannot resist, make sure they are well protected from the wind and cut out the dead wood as the trees begin to leaf out. Keep your ears to the ground and when the National Arboretum releases new reds, get one.

The miniature, or dwarf, hardy crape myrtles, Chickasaw (pinkish lavender) and Pocomoke (deep rose-pink) grow to a maximum of three feet, but are specialist rather than general-use shrubs. Two have done well in the excellent drainage of a dry riverbed at LongHouse Reserve. In my own garden in a raised bed, a mature plant died back to the ground, but has resprouted and looks none the worse for wear.

Dr. Mike Dirr, the woody-plant guru, has introduced a group of six dwarf plants in the Razzle Dazzle series that I’ve seen in local garden centers, and Monrovia is marketing three of his mid-sized trees in what they call the Barnyard series. Information about the genetics of these plants is not readily available, which would make me leery of trying more than one to test for hardiness.

The last two winters have shown that not all crape myrtles are created equal. But if you choose your planting location and cultivar carefully, you will be successful. A row of elegant white crape myrtles, Lagerstroemia Natchez, at the railroad station in East Hampton has withstood the test of time. Protected by a windbreak of trees and shrubs on the northern side of the tracks, it is a model of success for all to borrow.

 

The red crape myrtles are dramatic but do not fare well over our winters, as seen in the die-back in this one. Abby Jane Brody