By Susan Albert
Don’t be afraid to prune. It is said that pruning at the wrong time won’t kill your plants, but it can weaken the plant if repeated over time. So mistakes can be rectified!
Generally, late winter and early spring—before new growth starts—is the best time to prune landscape trees, grasses, and shrubs in Oklahoma and Texas. Pruning can increase the vigor and health of shrubs, keep heights in check, and rejuvenate older bushes. Trees properly trained while young need little to no pruning when mature.
In early spring you can safely prune summer- and fall-blooming shrubs such as spirea, glossy abelia, and blue mist. But hold back on pruning spring-blooming trees and shrubs till after they flower. Many formed their buds last summer and autumn on old wood, and pruning too early reduces their display. Examples include azalea, rhododendron, flowering almond, flowering quince, loropetalum, and forsythia shrubs, as well as the Eastern redbud tree, shown right. However, you can remove dead or diseased wood anytime you notice it.
Some tools necessary for pruning are hedge shears, hand pruners, loppers for cutting stems 1/2 in to 2 in thick, and pruning saws for cutting larger branches. Make healthy cuts at a 45-degree angle close to a bud.
Here are tips for pruning some common woody plants:
- Prune crape myrtles in late winter. Avoid chopping them straight across the middle—a.k.a. “crape murder.” To form a more natural shape, remove all but three to five of the strongest limbs at the base. Then remove the lateral branches up to a third to half the height. Also remove any suckers growing from the base. It’s not necessary to cut off the seed heads from last year unless they are in easy reach. Eventually they fall off, and new blooms replace them. A crape myrtle, surrounded by abelias, is shown below at the Linnaeus Teaching Gardens in Tulsa, Oklahoma.
- Glossy abelias bloom on new wood, so you can prune them in early spring. Remove dead stems; to encourage bushier growth you can cut up to a third of stems back to the ground. I also like to cut back those awkward shoots that are taller than the rest of the plant. Trim those even with the rest of the shrub whenever you notice them.
- You can reduce shrub roses, such as Knock Outs, floribundas, and grandifloras, to about 2 ft each spring before new growth leafs out. A Double Knock Out rose is shown below.
- Spireas bloom during the summer, so prune them in early spring, if needed to control size or rejuvenate the shrub. An exception would be an early-blooming species, such as bridalwreath spirea, which you should hold off till after it flowers.
- Blue mist shrub grows woody if it’s not cut back. Trim it back to the ground each spring for a spectacular fall show.
- You can prune althea shrubs in a tree form, like crape myrtles, or leave them rounded. Typically altheas bloom summer to fall, so prune them in early spring to train their shapes or control their sizes.
- You can cut back butterfly bushes every spring to within 6-8 in of the ground. They quickly regrow and beckon pollinators by early summer.
- Hydrangeas bloom on old wood, new wood, or both. Old-fashioned types, such as mopheads, lacecaps, and oakleaf hydrangeas, bloom on old wood or last year’s stems. Those buds form in fall, so it’s important to trim them, if necessary, after their summer blooms. H. paniculata and H. arborescence types bloom on new wood, so cut them back to the ground, if desired, in fall or winter and they rise anew. The ‘Endless Summer’ varieties bloom on old and new wood, blooming first on old wood, then later in the summer on new wood. Prune them lightly in fall to control shape.
- Hollies are a favorite of many gardeners, and you can lightly prune them any time (holiday décor). For more important pruning wait till late winter or early spring, just before new growth starts.
- You should prune other evergreens, such as yews and junipers, before new growth starts in the spring.
Using hedge shears or hand pruners, cut grasses, such as miscanthus, to about 8 to 10 in or to new growth. Mow groundcovers, such as liriope or mondo grass, if the area allows.
Remove dead wood on deciduous trees anytime. But the least stressful time is late winter or early spring, before the trees leaf out. Trees with flowing sap, such as birches and maples, may “bleed,” but that does not harm the tree. Trim branches within reach, but leave higher limbs to professionals.