Plant Answers

Pruning Ornamentals

One of the most common, yet least understood, aspects of home gardening is pruning. Pruning can be a simple process; the "basics" are few, and once understood, can be mastered quite easily.

Proper pruning can turn a tree or shrub into a beautiful plant specimen; improper pruning can result in headaches, heartache, and "butchered" plants.

Nearly any tree or shrub must, from time to time, be pruned in order that it will maintain a desired size or shape, or for the removal of dead or diseased branches. The questions that come to the home gardener’s mind when it comes time to prune are endless.

One of the most frequent questions we often hear is, "Why should I prune?" That's a good question, and here are some familiar problems that you can solve by correct pruning:

1. DEAD OR INJURED LIMBS: Dead, broken or diseased branches should be cut out as soon as possible with a sharp saw. Be sure to paint the wounds with a tree-wound dressing.

2. SHAPING: Shrubs, trees, roses, etc. may be shaped by pruning to conform to the original idea you had when you planted them. This is especially true in the case of "specimen" shrubs (topiary plants) and espaliers. They must be regularly pruned or trimmed to maintain the desired shape.

To encourage a tree to spread widely, remove its leader. To grow more upright, prune its side branches; to grow more open in the center, remove some of the branches back to the interior of the trunk; and to grow more compact, clip the ends of all branches.

4. LIGHT AND AIR: If a plant is too thick in the center, so that little light and air reach the interior, thin it out by selectively pruning some of the interior branches.

5. LARGE FLOWERS: Remove the small buds that have sprouted beside the larger ones. The strength goes into the remaining larger bud. When you do this you are forcing all of the "plant energy into the production of a single flower or blossom. This procedure is commonly called disbudding."

6. NEW GROWTH: You can bring about new stem growth by heading back, which means pruning so that the outward growth is cut back toward the main stem. Pruning on top will tend to increase the foliage and branches toward the sides. If you prune the roots, the plant will stop growing somewhat, but will develop more fruit and blossoms.

Another question most frequently asked is "When to prune?" There are a number of general rules that you can safely apply. For example, the time to prune any shrub or tree depends on when the plant blooms. Spring-blooming deciduous species are pruned after the blooming period, as are some evergreen types. When you prune one of these, you are inducing the formation of flower buds for the next season.

Summer and fall-blooming shrubs are usually pruned in the late fall and winter. New growth comes out by spring, bearing new flowers.

Evergreens where flower production is not important, such as ligustrum, pittosporum, euonymus, can be pruned anytime, but always remember that there should be a reason or need before any plant is pruned.

The main purpose of pruning vines is to limit growth, remove dead wood, and thin stems and branches. Pruning also helps to promote new growth and improve flowering. Some fast growing vines can be severely cut back to induce growth close to the ground, others require periodic severe pruning or complete cut-back at or near the ground level. Severe pruning will not be harmful if done early in the spring before new growth starts.

The growth and development of vines are influenced by the type of support they have. It is important to know how a vine climbs in order to achieve the best support and ease of maintenance.

One group of vines climbs by attachment to the wall or support with root-like hold-fasts or modified tendrils with circular discs. A second group climbs by winding tendrils around a wire support or trellis. Others climb by twining the vine itself around the support.

Each individual must use his own imagination and sense of beauty to train vines for a specific design or landscape need. Some general pruning requirements must be met:

- Virginia Creeper and Boston Ivy (Parthenocissus): Prune branches to control spreading, cut back to or near the ground.

- Honeysuckle (Lonicera): Thin stems and branches to encourage new growth.

-Silverfleece Vine (Polygonum): Can be cut back to the ground each year.

- Trumpet Creeper (Campsis): Each year cut stems back three to four buds to promote new growth. Cut tops back to encourage the vine to branch.

- Wintercreeper (Euonymus): A useful vine and ground cover. Prune the branches back to control spreading or stems growing out from a well or support.

-Wisteria: Prune back stems to 3 or 4 buds each year to promote new growth and flowers. The tops can be cut back to induce branching.

Ground covers may require pruning to keep them within bounds, to remove old or dead growth, or to rejuvenate the planting. Evergreen ground covers, such as English Ivy, Vinca or Euonymus Wintercreeper, benefit from periodic cutting back or shearing to promote vigorous new growth and to keep the beds neat and more disease free.

Some established ground cover plantings become overgrown with long or straggling branches and stems. Grounds maintenance workers sometimes use hedge shears and rotary mowers with high wheels to mow off accumulated stems and branches. The debris can be removed with leaf rakes or industrial vacuums.

Evergreen and deciduous ground covers that show winter injury to foliage and branches can be cut back or sheared. Prune out individual damaged branches. Ground covers may be pruned at planting time to encourage more branches and new stems to grow from the base or along the main stem.

Pruning shears are used for branches ½- to ¾- inch in diameter. Shears are strained and weakened when twisted to cut larger branches. Scissors or draw-cut hand shears are preferred for close cut precision pruning. Anvil type pruning shears are satisfactory for general pruning. Grass shears or hand or electric hedge shears are useful for cutting back the tops of ground covers in large beds. Lopping shears have long handles and are designed to cut larger branches ¾ to 2 inches in diameter. Pruning saws, with narrow blades and coarse teeth, are designed to cut on the pull stroke. Small curved pruning saws are useful to prune larger branches.

For more information about pruning, see:

http://aggie-horticulture.tamu.edu/extension/pruning/pruning.html