Pruning is the practice of removing parts of a plant to help achieve a goal. People have pruned trees and shrubs for eons, and for many reasons. Understanding why a plant might be pruned will help you approach the task in the best manner. Reasons for pruning trees and shrubs include repairing damage, improving the plant’s growth habit and health, restricting the size or form of a plant or simply making the plant conform to your needs. Before you begin, have a plan. Learn what is natural for the plant and why your plant grows the way it does. Don't be intimidated by pruning. You will quickly learn that a few basic principles apply to most situations.

Are there basic styles of pruning? Most pruning is either informal (with a goal of having the plant look much like it would in nature) or formal (making the plant conform to a specific shape or size that wouldn't occur naturally). Deciding what you want the plant to look like will help you know how to prune.

Are there different ways of pruning? Exactly where you cut will produce different results, such as thinning, heading, shearing and pinching.

What is thinning? Thinning (also called selective pruning) is done by taking a branch off where it starts. This leaves other branches with terminal buds that keep the new growth natural in style. Trees and shrubs can be thinned without stimulating lots of new growth.

What is heading? Heading is removing a significant part of each branch, quite often just above a bud, leaving stubs. Removing the terminal end on a branch often stimulates lots of new shoots and branches will develop from dormant and lateral buds just below the cuts. While this may be a quick, inexpensive way to prune, heading may result in unnatural looking, unhealthy plants.

Is heading different from shearing? Shearing is when you remove a small amount of the ends of all the outer branches. This usually removes most of the terminal buds and results in lots of growth on the outside edges of the plant. Shearing is only advised for formal hedging and must be done frequently to maintain the form.

What is pinching? Pinching is removing the tip of the leader (the central or dominant branches) of the plant. Pinching is used to encourage new growth. Occasionally, this new growth will have to be thinned later.

How do I decide which method to use? Find out the natural form of your plant, then work with the plant's natural habit instead of against it. While many plants are somewhat flexible, it can be extremely frustrating for you (and unhealthy for your plant) to try to make it conform to an unnatural shape or size.

What kind of pruners will I need? Pruners are available with either long or short handles. Often long handled pruners are called loppers and short-handled pruners are called shears. Pruners are even available mounted on a pole to extend your reach. On some pruners, the blades pass by each other, like a scissors. These are called bypass pruners. Anvil pruners work more like wire cutters, with the sharp blade pinching the branch against a wider, flat surface. Bypass pruners make a much cleaner cut, especially with larger branches.

If I need a saw, which type is best? There are lots of styles of saws available and most of them do a good job. Choose a saw that fits your hand comfortably and can fit into the space where you are working. Double edged saws may be tempting, but too often you end up injuring nearby branches accidentally.

What about hedge shears? There are several types of hedge shears available, but not many uses. Unless you are working with lots of formal hedging, hedge shears do not give you enough control over what is being cut.

Do my tools need any special care? Simply keeping your pruners and saws sharp and clean will make your pruning job much easier and result in clean cuts that will heal more quickly.

When taking out large branches, how close should I make the cut? Recent research has made some changes in how we prune plants. When taking off branches larger than your thumb, it is important not to make flush cuts. The plant will heal faster if you leave the branch collar intact. The branch collar is a raised area where the branch meets the larger branch or trunk. Cutting into the branch collar often results in decay. At the same time, it is important not to leave a stub, for it will be a site for decay too. If a branch is very large or heavy, make an undercut first. This will help avoid the weight of the branch tearing away bark and causing damage as it falls.

What if I want to shorten a branch, instead of removing it? When taking off part of a branch, make a slant cut (~45º) about a quarter inch above a bud. Keep in mind that the new growth will head in the direction of the last remaining bud.

Should I seal the cuts with pruning paint? Unless the plant you have pruned is susceptible to disease transmission through open wounds (such as oaks and elms), it is better to leave the wound bare.

How do I know when I should prune? This is probably the most frequently asked question about pruning, and in many types of plants, when you prune is as important as how or why. If you are just removing dead or damaged branches, you can do it anytime. But if you are going to be pruning out healthy wood, find out what is best for your specific plant. You need to know if your plant is deciduous (shedding its leaves each season) or evergreen.