BERTAUSKI COLUMN: Don't murder crape myrtles

I parachuted once.

It was shortly after I flew for the first time. For some reason, I decided it would be a great idea to jump out of a plane. It was exhilarating and terrifying, and I promised never to do it again. I've never had a problem keeping that oath.

As promises go, here's another one I've never broken: Never murder a crape myrtle. Contrary to what some folks are led to believe, crape myrtles do not require severe pruning. There are times when problems need to be corrected, but crape myrtles do not need to be cut back like deer antlers.

In general, pruning can be done any time of the year. Winter is considered an ideal time because the form is easier to shape. Pruning wounds in spring will bleed sap. While that may seem harmful, the only issue would be the unsightliness of it.

There are some pruning rules, depending on the plant. Trees and shrubs valued for their flowers set buds on last year's growth or the current season's growth. Azaleas, for instance, set flower buds last summer. If they are pruned after July, this year's blooms are removed, resulting in fewer and often spotty flowers.

However, some cultivars bloom on last year's growth and the current season's growth. Encore azaleas and Endless Summer hydrangeas are good examples and, as a result, have longer periods of flowering.

Crape myrtles bloom on the current season's growth. They are fast-growing trees with prolific flowers on new growth. And when crape myrtles are severely cut back, called hat-racking, they respond by growing even faster. Any plant that loses a limb means losing leaves, and that means losing photosynthetic tissue and food production. When a crape myrtle has the majority of the limbs haphazardly removed, it responds by growing several limbs at each cut to replace what was lost. These fast-growing replacement limbs, called water sprouts, are weakly attached and break off easily. They also are succulent and susceptible to disease.

This practice likely became commonplace because water sprouts can grow several feet in one year. Since crape myrtles bloom on new wood, the theory suggests more flowers will bloom because there's more new wood, but this isn't necessarily true. Clemson has proven that correctly pruned crape myrtles flower more profusely than those severely pruned, illustrated at www.clemson.edu/crapemyrtle/culture/pruning.html.

This practice of severe pruning stresses the tree by removing excess tissue and forcing it to exhaust carbohydrate reserves to replace them. One sign of a stressed tree are sucker branches growing at the base of the trunk. Stress can predispose the tree to insects and disease.

Another issue with hat-racking is the destruction of the tree's form. Crape myrtles are valued for their bark as well as form, both of which are altered or lost in this practice.

Correct pruning cuts a branch at its base, never in the middle. The wound seals quicker, and fewer water sprouts result. Cutting a branch at the base -- all the way back to another branch -- maintains apical dominance. This reduces water sprouts growing around the pruning cut, preserves the form and maintains healthy growth.

You say your crapes already have been murdered? It's not too late. Cut all the water sprouts back to the knob except one to re-establish apical dominance for one branch. The water sprouts will return, but persistent pruning eventually will allow the lone branch to establish control, and the water sprouts eventually will stop.

Right now is still an ideal time to prune. Examine trees for cross-branching, where one branch has grown against another. The rubbing will result in wounding, and one branch needs to be removed. The form sometimes may need pruning in order to train it to grow in a certain direction or to avoid low-growing limbs. Just remember to prune at the base of the limb. And never murder it.

Tony Bertauski is a horticulture instructor at Trident Technical College. To give feedback, email him at tony.bertauski@tridenttech.edu.