When is the best time to prune flowering trees and shrubs? The answer depends on whether the plant produces flowers on old (last year’s) or new (this year’s) growth. 

“Crepe murder,” which is the cutting of crepe myrtles back to main trunks every fall, causes the plant to have fewer blossoms in the spring and makes a strange looking, if not downright ugly plant, and causes spindly new growth each spring. Like other trees, crepe myrtles should be pruned only by selectively cutting out whole branches to maintain the shape of the plant. 

Crepe myrtles should be pruned by selectively cutting out limbs back to a major node. Trees should only be pruned to maintain shape (not size), to remove dead or diseased wood, or to keep limbs from contacting structures.

The most important reason for pruning flowering shrubs, and to a lesser extent trees, is to maintain a large portion of the plant as young, vigorous wood. Since most flower buds are formed on current or previous year’s growth, you can remove up to one third of the oldest wood annually to keep the plant vigorous. Such pruning will stimulate future flower and fruit development. 

Here are some rules for pruning:

Prune flowering shrubs that bloom in spring within a month after flowering. Prune summer flowering shrubs between January and March, before new growth starts. To keep a base of a hedge leafy, cut into a pyramid shape in spring, so that the top is narrower than the base.  If a hedge is too dense, cut it back to the main stems on one side only. Let the hedge recover and produce new growth for a year, then cut back the other side. If the hedge has become too tall, cut back every second shrub to within a few inches of the ground. New shoots should sprout around the severed trunks. Cut back the remaining shrubs the following year. Shrub roses are best pruned in winter. As both old and modern roses produce most of their flowers on shoots produced from old wood, prune lightly. Remove dead, thin and decayed wood, and shorten main stems by about one third. Rambling roses should probably be pruned after spring/early summer bloom. Cut untidy, flowered shoots right down to the base and tie new shoots to the trellis or support. If there are only a few new shoots, leave some of the flowered shoots in place, cutting back just a little. Climbing roses are also best pruned after spring/early summer bloom. Remove any crossing or thin shoots and reduce the height of the main stems by about one third. Remove any side shoots that spoil the shape and cut back the others by about two thirds. Miniature roses should be pruned in February. Cut off any dead, diseased or thin wood and trim back the main stems to about one third of their length. For more information contact the Erath County Extension Office at 965-1460.

Lonnie Jenschke is an Erath County extension agent.