Many gardeners find even the thought of pruning intimidating. A branch or a twig once removed cannot be replaced and that thought stays their hand. By giving some thought to the purpose of pruning the job becomes less traumatic for both the gardener and the plant. Plants are pruned to ensure their health and vigor, to free them of structural weakness, to reduce the risk of disease and enhance their ornamental features.

The simplest approach to pruning makes the task understandable and accomplishes most of the desired results. Begin by removing dead, diseased or damaged wood, the three "D"s of pruning. The material to be removed is easily defined and the gardener is not paralyzed by indecision. The confidence and knowledge developed performing these early operations prepare the gardener for the more complex task of pruning to alter the shape of a plant.

Before making the first cut it is important to understand a few basic things about a plant's anatomy. Of primary importance is a process called apical dominance. It means a twig, branch or leader tends to grow upward or outward from its tip. At the end of every shoot is a terminal bud called the apical bud. The growth of the shoot is controlled by this terminal bud. It attracts the major portion of the resources supplied to the shoot and suppresses the growth of buds below it on the shoot.

The farther a bud is from the terminal bud the greater its rate of growth. This growth, however, never equals or exceeds the growth of the terminal bud. Should the terminal bud be damaged or removed, the bud below it assumes apical dominance. It is possible this bud was latent and not visible before the loss of the original terminal bud allowed it to grow.

Every shoot, twig, branch, stem or trunk of a plant consists of three layers. The outer layer is the skin or bark. It minimizes moisture loss and protects the inner layers. The second layer is the cambium. It is the growing layer of the plant and is vitally important. Although only a fraction of an inch thick in even the largest trees, the cambium provides all the new cells in a plant. Cells produced on the outside of the cambium layer become bark. Cells produced on the inside of the cambium layer become vascular bundles and transport food and water to the leaves.

The vascular bundles are supported in the third or inner layer by pith cells that die and become lignified. The lignified cells become the heartwood of the plant.

Diseased or damage plant tissue cannot heal, Instead the plant forms a natural barrier to disease between the diseased area and healthy tissues, isolating the main part of plant. The barrier is formed by a chemical action and is reinforced over time. The isolated portion dies, dries, becomes brittle and is shed.

Begin pruning by removing all the dead wood. Dead wood is not only unsightly, it is colonized by harmful organisms and is a source of infection. Fungus infections may be visible on the outside of the dead wood.

Next, remove damaged wood. Branches that are partially broken by lightning, the weight of snow or ice, vandals or grazing animals rarely heal. Remove all of them. The branch on the holly shown in the photograph on the right was damage by the weight of snow that accumulated on it. Both the branch and its parent should be removed.

Bark that has been knocked loose or torn off is unlikely to reunite with the cambium layer. Trim the ragged edges of the cambium layer and hope that the cambium layer can fill in the wound.

Diseased wood is harder to recognize than dead or damaged wood. Careful observation is the beginners best tool. The infected stem or branch is going to look different from the rest of the plant. Wilted or dying leaves are an obvious indication of trouble. Some infections cause cankers to form at the point of infection. The area changes color and is sunken. In some cases the fruiting structures of fungi can be seen. Take a sample of the affected branch to the local Cooperative Extension office if you need help.

Cut into live wood if there is a fast moving infection that has not been isolated by a barrier layer. This type of infection is usually found on soft tissues that have not matured and hardened. Do not remove the barrier layer if it has formed. The plant would have to use its resources to create another barrier.

After removing the dead, diseased and damaged wood, examine the plant for potential damage. Look for branches that rub together or cross each other and remove the weaker of the two.

The tree or shrub is now much better than when you began and you may decide to rest content with your labors.

Timing is critical for pruning ornamental shrubs and is related to age and type of flowering wood. Late summer and autumn flowering shrubs bloom on the current season's growth. Prune these plants in the spring.

Spring and early summer flowering shrubs bloom on the previous season's growth. Prune these plants after they flower. This allows new wood to grow and ripen before the plant blooms the following spring,

There are three basic pruning tools that should be in every gardener's potting shed. They are pruning shears, a lopper, and a pruning saw.

Pruning shears are scissor-like instruments that are operated with one hand. There are two types of pruning shears, anvil and bypass. The blade of anvil shears cuts against a flat surface, usually about 1/4" wide. As the blade cuts through the branch or shoot, it presses the branch against the anvil and causes crushing damage. Proponents of anvil pruning shears feel the damage is not significant. Anvil pruners also leave a short stub when used to remove branches.

Bypass pruning shears perform more like scissors. The cutting blade moves past a beveled, noncutting, hook-shaped blade. A close cut is possible with bypass shears. It is possible to remove twigs and branches without leaving stubs.

Pruning shears are intended for removing woody material up to the size of a pencil. A proper cut should be clean and require little effort. Cuts that requiring twisting of the pruners damage both the plant and the shears.

Plant material too large to be removed with pruning shears can be removed with loppers or a pruning saw. Loppers are long handled pruning shears. They have heavier blades and stronger handles. Two hands are required to make a cut with loppers. As with pruning shears, there are anvil and bypass types. Loppers are capable of removing material up to 1-1/2" in diameter. Do not attempt to cut branches that are too large to fit comfortably in the jaws of the lopper.

Pruning saws are small saws with a wide set to the teeth so they can cut green wood without binding. The teeth are shaped so they cut on the pull stroke. Often they are made with a folding blade. Pruning saws can remove limbs up to three inches in diameter.

Both loppers and pruning saws are available mounted on a pole to extend the gardener's reach. The two implements are often combined in a pole pruner. Poles are made of wood, metal or fiberglass.

Power tools are available to speed the task of pruning. They are dangerous and are best left to professionals.

Do not cut a limb that is under tension. This is doubly important if you are using a chain saw. Always wear safety glasses and gloves. Check for thorny stems that could injure as they fall.

Cutting to a bud is used to shorten a shoot or when removing damaged or diseased wood. The angle of the cut is determined by the type of plant being pruned. Alternate bud plants are pruned with a slanting cut 1/4" above the bud.These plants have the buds staggered along the shoot as shown in the first example in the drawing on the left.

Opposite bud plants are pruned with a square cut made as close as possible without touching or damaging the buds as shown in the second example in the drawing on the left. Usually a pair of shoots develops when an opposite bud shoot is pruned.

Remove branches at the junction of the branch and its parent. At this point there is a raised collar around the branch. It is important that this collar remains undamaged on the plant. In this specialized area of the cambium layer, cells divide rapidly to form scar or callus tissue which closes the wound when a branch is removed.

Small branches can be removed with a single cut using pruning shears or loppers. Larger branches are removed with a pruning saw in a series of cuts. This is done to prevent the weight of the branch from tearing a strip of bark from the plant as the cut is almost complete.

The first cut is made on the underside of the limb, between three and four inches from the trunk. Cut approximately one-fourth of the way through the limb.

The second cut is made is made approximately an inch further from the trunk than the undercut. Remove the limb with this cut.

The third cut is made at the branch collar to remove the stub. Support the stub with one hand to prevent it from tearing bark as the cut is completed. See the illustration on the right. Smooth the wound with a knife.

Never leave a stub when pruning. The stub always dies and the wound cannot heal over. The dead stub provides an entry point for insects and diseases. Hollow trees begin with dead stubs.

For years pruning wounds were covered with special paint as an aide to healing. It is now believed that wound paint provides no benefit to the plant and may, in some cases, cause harm.