The hardest thing about pruning trees is getting up the courage to make the first cut. After that, each cut gets a little easier. The fact is, the second hardest thing about pruning is knowing when to stop. But both problems can be solved with a little knowledge of how pruning works and why it is good for our deciduous trees and especially good for our fruit trees.
There are two main reasons for pruning. The first is to improve a tree's shape and size, and it is the purpose behind pruning of ornamental --and shade trees. The second is to improve fruit production, and it is especially critical for owners of fruit trees who want a good harvest next summer. Both reasons center around improving the health of our trees.
January is generally a good month for pruning deciduous trees. By mid-January, most deciduous trees are in the deepest phase of their winter rest, a condition called full dormancy. It is extremely important that a deciduous tree be fully dormant before it is pruned. Pruning a tree when sap is still flowing in its branches may stimulate the tree to bud prematurely while we are still facing danger of frost, or it may open the pruning cuts to infection by airborne fungi. To make certain your tree is in full dormancy, break off a few small branches and check the ends for sap flow. There should be a little moisture still present in the branches, but not enough to ooze or flow from the break. And, of course, a tree that still has leaves is very much "awake" and should not be pruned in mid-winter. This includes non-deciduous trees such as evergreens which should be pruned from summer to fall. Also, hold off on pruning those rose bushes until early spring. Roses are not heavy, sleepers.
Once you've determined that your trees are fully dormant, it's time to inspect the tool shed. You'll need a pair of hand-held pruning shears; loppers, which are pruning shears on-a-stick; and a pruning saw. All of your pruning tools should be well constructed with sharp blades. You may also want to invest in a spray can of pruning paint to seal off any pruning cuts larger than a pencil. There is some disagreement over the importance of applying pruning paint. Some gardening experts believe it is essential to keep pruning cuts from drying out and cracking, while other experts argue that it really isn't necessary, and a few believe using pruning paint actually increases the likelihood of a cut drying out. Since the verdict is still out, you'll need to decide this one for yourself. Pruning paint must be applied immediately after pruning in order to be effective.
So now that you've checked your trees and they're fully dormant, sharpened your tools, and made up your mind about pruning paint, it looks like you're ready to start cutting. Before you head out, you might want to review some pruning fundamentals. Knowing why you should prune out one branch and not its neighbor will help you make good decisions when you have pruning shears in hand. The following paragraphs offer a quick overview of how pruning works, some good pruning techniques, and suggestions for the pruning of specific fruit trees. A word of caution: if you've inherited an older, unpruned tree, don't try to prune it all in one year you'll end up handicapping the tree by removing too much healthy wood at once. Space it out over two or three years.
How pruning works. Pruning removes part of a tree's top growth and reduces the demand on the roots for nutrients. The tree now has more energy (nutrients) to dedicate to healthy new growth and top quality fruit production. You can channel this energy into specific areas of your tree by placing your pruning cut directly above a bud or side branch (a header cut). The bud will then develop into a side branch, or the already existing side branch will become stronger and more dominant. By removing an entire branch (a thinning cut), you can remove dead or damaged wood, long droopy branches, or fruit-bearing wood that is no longer productive
Header Cuts. When making a header cut (used principally on fruit trees), prune out 1/3 or 1/2 of new growth from the branch and make the pruning cut above a bud, side branch, or main branch that will grow in a favorable direction. In windy locations, it is best to select a bud or branch that will grow into the wind to reduce the likelihood of it breaking. Make all of your cuts on an angle, with the bud or branch on the high-side of the cut. On a tree less than four years old, concentrate on creating a strong branching system. Be wary of making header cuts on older branches with no side branching. The latent buds on these branches may have been dormant for too long to develop.
Thinning cuts. When making a thinning cut (used on fruit and shade trees), prune out the entire branch, making your cut close to its junction with the main branch. Never leave a stub. If you are removing a large diameter branch, make a preliminary cut underneath with your pruning saw to keep the bark from tearing when the branch is cut. Eliminate "crow's feet" (places where three branches join) by removing one of the branches and leaving in place the two branches that form the widest angle. This is the stronger union and allows more room for side branching.
Pruning shade trees. Concentrate on thinning out congested branches and shaping an aesthetically pleasing tree. It is best to allow shade trees to grow naturally. It is healthier for the tree and will save wear and tear on your pruning shears. To encourage branching high enough on a shade tree to allow for travel beneath it, shorten the branches that grow below where you want branching to begin. Don't remove them completely in the first year or two. The leaves on these shortened branches will supply nutrients to the crown of the tree and lead to faster development than if you just lopped them off. To shorten an overambitious shade tree, cut the tallest branch lower than the rest of the branches. This is better than shearing all of the top branches equally because it still retains the natural shape of the tree.
Pruning fruit trees. Concentrate on making header cuts to increase side branching and fruit production, and thinning cuts to remove congested branches and improve the shape and size of the tree. Thin out branches that are growing straight up (except in pear trees), straight down, or toward the center, as well as branches that are touching or crossing. It is important to know the growing and fruiting habits of the specific fruit tree you are pruning or you may inadvertently prune, out the best of your fruit-bearing wood. In that sense, pruning fruit trees requires more care than pruning shade trees.
* Peach and Nectarine: These fruit trees are vigorous growers with fruit occurring on the previous years new growth. This growth produces fruit only once and then becomes unproductive. You need to prune hard to encourage side growth from these older branches. Remove about 2/3's of the new growth on each branch, but do not cut back to two year- old wood. (You can often tell new growth from old by color changes in the bark as you move down the branch. Older wood is usually a duller shade.) Peach trees are naturally multi-trunked and vase shaped. Thinning cuts should be used to prevent crowding of trunks and to open up the center of the tree.
* Apricot and plum: These fruit trees are almost as fast growing as peach, but their fruiting habit is different. Apricot and plum trees produce both fruit-bearing branches and fruit-bearing spurs. Spurs are stubby fruit-producing twigs up to 3 inches long and often resemble long thorns with buds. Never prune spurs from your fruit trees. These spurs will remain productive for three to five years. Apricot trees are naturally multi-trunked and vase shaped. Remove older side branches to encourage new spurs to form and cut off 1/3 to 1/2 of the new growth on each branch to promote new side growth.
* Apple, Pear, and Cherry: These fruit trees grow much slower than peach or apricot and produce little fruit-bearing wood each year. Pruning consists of thinning out dead, rangy, or crowding branches, with only minimal header cuts. Apple trees are naturally central leader (having one dominant branch) with fruit-producing spurs occurring on two-year-old wood. These spurs can continue to bear fruit for five to eight years. Pear trees can be central leader or multi-trunked, though all of their branches seem to grow straight up. They also produce fruit on long lasting spurs growing on two-year-old wood. Cherry trees are similar to pear in that they can be central leader or multi-trunked.
* Citrus trees: There are few citrus trees in Cochise County and, in general, citrus trees are not pruned. The exception (there is always an exception) is the lemon tree. Lemon trees produce strong, upright growth on their main branches that should be removed as soon as it appears. These are suckers and are rarely productive.
* Frost damage: Hold off on pruning frost damage from your trees until early spring when there is no longer a danger of additional damage and you can distinguish between the dead and live wood.
Although this pruning review by no means covers all aspects of pruning, it should help you get started on your winter pruning project. If this winter continues to be mild, you need to be certain to check your trees for dormancy before beginning to prune. Sources consulted for this article include Sunset Western Garden Book, George Brookbank's Desert Gardening, and Plants for a Dry Climate. These and other sources of pruning information are available in your local library or bookstore. Happy pruning!