To Prune or Not to Prune

Guest Author

By Calvin Finch, Ph.D., Guest Author

February is the best time to prune most plants, but do not prune for the sake of having something to do. Prune to control plant size, remove unsafe branches, remove dead wood and, in some cases, to shape or maximize production of flowers.

Pruning Paint

Pruning paint is not necessary except in the case of live oaks and oaks in the red oak family (Schumardi, Texas red, Spanish, etc.). Paint the wounds over 1-inch in diameter within 30 minutes of pruning to protect the plant from oak wilt.

Crape Myrtles

Crepe myrtles are the species that is most savaged by our urge to prune. They bloom on the new wood that grows in the spring so the theory is that heavy pruning stimulates lots of new wood. The theory is correct, but to get the maximum bloom you do not need to hack off the tops to leave stubs. If your crepe myrtle is relatively young and growing in full sun, it may put on enough new growth that pruning is unnecessary. In other situations, some of the thinning cuts we describe later in this article will do the job without leaving an ugly plant.

Thinning Cuts

Thinning cuts are the best. A thinning cut occurs when you follow the offending branch to its origin on another branch and cut it there. (See diagram below.)

Hedging Cuts

Hedging cuts are less desirable because they disrupt the tree’s hormonal control. Hedging cuts are cuts that remove part of a branch, a cut that leaves a stub. See the Pruning Guide in the appendix for a diagram of contrast between hedging and thinning cuts.

Roses

Old-fashioned roses often are only pruned when they get “out of hand” but the modern hybrid tea roses are blooming machines that do best when they are pruned every year. Prune them in late February. Select three or four main stems that are finger- to thumb-size in diameter. They should be spread around the plant arising above the graft and radiating at a 60-degree angle. Remove everything inside this frame so the middle is open to air and light. Also remove wounded wood, tangled wood and wood growing inward or straight up. Old wood should also be removed in favor of green young wood. Do not be afraid to cut; it is hard to over-prune a modern rose.

Ornamental Grass

The top of ornamental grasses will die back after the first hard freeze. Many gardeners choose to leave the dead tops in place to add visual interest and to provide cover for birds. The dead top may also protect the roots during the colder winter. However, you will want to give the grasses a “hair cut” sometime in late winter or early spring. Cut them back severely when you do with pruning shears to within six inches of the ground. There will be healthy and attractive new growth as the weather warms.

pruning_ornamentalgrass

Pruning Exceptions

Exceptions to the February pruning recommendation include the early bloomers and conifers. Prune Texas mountain laurel (if it needs it), climbing roses, ornamental fruit trees and other early bloomers after they bloom. Prune conifers after the first flush of growth is complete and only remove one-half of the new growth.

pruning

Pruning Tips

  • If you suspect that a plant you prune may suffer from a bacterial or fungal infection, it is important to clean your pruning tools before using them again. Signs of a problem could include a center of rotted wood, split bark, or large dead branches.
  • Clean pruning tools with a mixture of 5 percent bleach (20 parts water and one part bleach). Once you are done, apply some tool oil to condition the metal. Appropriate oils for this task can be found at home improvement stores.
  • Sharp pruning tools are easier on both plants and your muscles. Use a whetstone or knife sharpener.
  • Pruning back trees (even crape myrtles) should be done thoughtfully. Avoid “topping” shown in the diagram below.

Calvin R. Finch is a director at Texas A&M Water Conservation and Technology Center.

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