How to Prune Trees Without Killing Them (step-by-step with pictures)

If you’re like most homeowners, you know that the trees on your property should receive an occasional pruning. However, the task is usually put off until, for the umpteenth time, you bump into a low-hanging branch while mowing the lawn. “That’s it.” you say. “Tree. your time has come.”

Typically, the tree is then attacked by a variety of tools. with limbs hacked off in a mostly random manner. When a large enough pile of branches has accumulated, the job is pronounced finished.

Unfortunately, in some cases, so is the tree.

Indiscriminate and unknowledgeable pruning can kill a tree. A dead tree is dangerous to have around, costly to both remove and replace, and lowers the value of your property.

But strangely enough. pruning a tree is one of the best things you can do for it. It’s an important and essential step in maintaining your trees’ health. The trick is knowing when and where to prune.

Every time you make a cut on a tree, you should have a reason for that cut. This article will give you those reasons by explaining the basics of pruning, some corrective tree surgery you can do. when to prune and what tools to use.

This topic, however. is sufficiently complex that I advise you to read any of the books in my reading list at the end of this article.

Why you prune

What’s hard for most people to understand is that pruning, properly done, strengthens rather than weakens the tree. It’s one of the best things you can do for your tree.

Benefits of Pruning:

  • it ensures good growth when transplanting or planting a new tree.
  • it controls tree form.
  • it produces a better appearance.
  • it keeps the tree healthy.
  • it can rejuvenate a tree.
  • it produces more and better fruit.
  • it removes branches that endanger property or interfere with overhead wires or nearby structures.

There are limits, however. A common mistake is to neglect a tree for many years. and then in a flurry of activity (such as after reading this article), prune too severely. Nor will pruning significantly alter the shape of a mature tree, especially a conifer.

Nature’s plumbing system

To prune effectively. it’s essential to understand how plants respond to pruning cuts. Fig. A identifies the parts of the tree to which this article will refer.

Think of each stem (twig, branch or trunk) as a channel — a plumbing system — carrying water and nutrients for growth. By diverting this flow of water and nutrients (shutting off one faucet, opening another) you’re able to shape your trees. stopping growth in one direction or speeding it in another more beneficial manner.

In pruning, the most important parts of a tree are the buds (see inset, Fig. A). The direction a plant will grow is determined by these buds. There are three types of buds: lateral, terminal, and latent.

When pruning, select the bud that will grow in the direction you want. Fig. B shows how growth will occur in the same branch pruned differently. If you want more outside branches (ones that point away from the trunk).

Choose buds that point to the outside of the plant. These are usually the most desirable anyhow. because they won’t interfere with the interior of the tree.

The “terminal” (or end) bud continues the outward or upward growth of the branch. If a terminal bud is removed, the next closest lateral bud inherits its strength and growth. In short, removing the terminal bud causes the growth of side branches.

Buds on the sides of branches are called “lateral” buds. These buds develop into leaves and eventually into scaffold branches. If the lateral buds are removed, growth is transferred into the terminal bud.

Buds that lie dormant for many years are called “latent” buds. They are the tree‘s insurance policy against damage. They may only start to grow after the tree has sustained damage to other branches, and it needs to reestablish the delicate equilibrium of crown size to roots.

Start them when they’re young

Pruning should begin when the tree is first planted.

Specifically, you:

  1. Prune away broken or girdling roots back to the healthy wood. Roots that wrap around the base of the tree are girdling roots. Eventually, a girdling root could kill the tree. However, it the new tree was sold growing in a large pot or tub, you probably need not make any compensating root pruning.
  2. Remove broken or damaged branches. These branches may be diseased; removal keeps the infection from spreading to the good wood.
  3. Prune to compensate for the transplanting. Before a tree is transplanted. there is a natural, healthy balance in size between the roots and crown (the top of the tree). These two parts rely on each other for manufacturing food for the tree. In the process of transplanting, many of the roots are severed. To help restore the tree back to its balanced state, parts of the crown should be pruned. A rule of thumb is to prune the new tree back by one-fourth. First. identity the leader (see Fig. A) you want to preserve, and then prune back the leader and lateral branches by about one-fourth (It the planted tree is 4 ft. tall. this would mean cutting away about 12 in. from other branches.) Fig. C shows what I mean.

Your goal in the tree’s first year is to make sure it survives the transplanting, not to preserve every leaf and skinny branch. Prune in order to establish the strong central leader you want, but also be a bit cautious. You don’t want so many wounds that the tree can’t heal and grow.

How to prune

First, study Fig. G to learn the correct cutting techniques:

  1. preventing damage to the bark and bark ridges.
  2. leaving a clean. slightly angled cut, which produces the smallest wound.
  3. avoiding long stumps, which are avenues fdr insect infestation and rot

Wound closure comes fastest when the cuts are smooth. So keep your tools sharpened so that you’ll get a clean cut without rough edges.

Make cuts next to, but not into, the branch bark ridge, which is located on the upper side of the branch. Cut at an angle to avoid leaving too much cut surface exposed. Leaving this bark ridge collar area and a smaller exposed surface will allow the cut to heal healthier and quicker.

Larger cuts, as when thinning, require two cuts to be made prior to the final cut (see Fig. D). This eliminates the problem of the branch ripping or tearing the bark on the underside as the branch falls. You may want to attach a rope to help support the large branch, then make the first cut on the underside of the branch about 12 in. from the trunk. Cut about one-third of the way through the branch, stopping before the saw binds. Make the second cut on the top of the branch about 1 in. out from the first cut. Keep cutting until the branch breaks free. Then cutaway the remaining stump.

In shortening in branch or twig, cut it back to an existing branch that you’ve determined is appropriate, or back to a lateral bud or dormant bud (dormant buds are at the base of all leaves). When cutting to a bud, cut to within about 14 in. of the bud, and as always, make the cut at a slight angle for quicker healing.

What to prune

You now know why you’re pruning and how to do it right. Now it’s time to examine your trees for:

  • Dead or dying branches. Cut them off back to another healthy branch, or back to the main trunk.
  • Branch stubs. Remove all too-long stubs back to the nearest healthy branch or trunk.
  • To correct the tree’s shape (see Figs. E. F and G). With younger trees, it’s possible to do a bit of corrective surgery to prevent the tree from developing two widely spaced, weak, forked branches (Figs. E and F). The ideal tree is shown in Fig. H. It has a strong central leader, and the scaffold limbs are spaced along the trunk with no two of them directly above and shading another branch.
  • Branches growing too close together. Too many branches too close together stunt the tree’s growth and spoil its appearance. Correcting the situation is referred to as thinning, and since you're removing whole branches, refer to Fig. D for the correct, three-step technique.
    Thinning opens up the tree to let in the air, light and rain necessary for the leaves on the inside and the lower portions of the plant to grow properly. Thinning also reduces the area where snow can build up and break limbs.
  • Rubbing branches. Remove any branches that are rubbing against each other. These branches create an open wound where insects can enter and disease can start. If untreated, a large portion of the tree can be lost.
  • Remove suckers and water sprouts (see Fig. A). Suckers are the ones at the base and trunk of the tree: water sprouts grow vertical to the trunk. They're unattractive, and they weaken the tree.
  • Weak crutches (see Fig. J). Remove branches that have weak or nary row-angle (less than about 30 degrees) crotches. Weak crotch branches are the most likely to tear away, damaging the bark and nearby branches.
  • Dangerous branches. Prune to protect people and property. Eliminate branches that are, or may be, on their way to interfering with overhead power lines; weak branches that overhang play areas, houses, or anyplace frequented by people; and low branches that make the tree climbable, attracting kids.

How do I prune conifers?

Trimming conifers, such as pine, juniper, and spruce, leaves a lot of people cold. They’ll blithely prune a maple or oak, but sidestep a conifer because they can‘t figure out what to cut.

There’s an important distinction that has to be made when dealing with conifers. With conifers you must both prune and shear. Pruning controls the tree’s shape and form; shearing controls the new growth. Pruning, therefore, is removal of plant pans that grew prior to the current season; shearing is the removal of a portion of the current season’s growth,

Pruning a conifer should be confined to dead or broken branches. or limbs that are interfering with buildings, power lines or such.

Shearing a conifer is done while the new needles (referred to as “candles”) are about three-quarters grown and before this new growth has hardened and become woody, Fig. K shows the lighter green of the new growth candles — what you’d shear — Compared to the darker color of the older growth.

A conifer’s new growth should be sheared just after it is completed, usually in late spring or very early summer (see Fig. K). Usually the new growth is a lighter shade of green than the previous growth, and is situated at the end of the branch. Shearing off about one-third of the new growth each year will keep the conifers growing slowly and within their intended space. Shear when the new growth is still soft. If sheared after the new growth has hardened, new buds won’t form and the tips become dead twigs.

Shear in the evening, after the tree has been watered, using sharp shears, to help avoid the problem of needle burn (also called “shear burn“), which occurs when a too-dry conifer is pruned.

Fruit trees are special

Fruit trees are “working trees,” so to speak, and your approach to them must be different. Fruit-bearing trees won’t always have a strong central leader as preferred for most other trees. In fact, commercial growers prune their orchards in a variety of styles in order to maximize fruit production.

Strong scaffold branches should be the primary result of pruning. Keep the tree’s branch structure fairly open so that light and air can reach all parts. This prevents diseases and also preserves the fruiting ability of lower limbs. The crowns of fruit trees are kept low to make it easier for pruning, spraying, and harvesting.

Each fruit tree type has different requirements. Please refer to any of the books in the “Additional Reading” list at the end.

When to prune

Okay, you now know the why, the how, and the what. You‘re all primed to make life better for every tree in your neighborhood. But hold on. the time may not be right.

The consensus is that the best time to prune living branches (dead and dying branches can be pruned anytime) is late in the dormant season (late winter), or very early in the spring prior to the beginning of growth.

Technically. most trees can be pruned at any time, but some trees are more susceptible to disease and infestation if pruned during the summer months. For example. elms and oaks are best pruned during December, January or February to reduce the chance of Dutch elm disease and oak wilt developing. By pruning during the colder months, wounds can heal before the hot and humid periods provide a starting point for fungal growth.

Some trees bleed. This free-flowing sap escapes after pruning or when branch damage occurs. It may look bad, but it usually causes no harm to the plant, as long as it doesn’t attract insects. These types of trees are best pruned during the dormant period.

Water sprouts and weak branches can be removed at any time during the summer months. Any other pruning during the summer is generally not recommended, except with newly planted trees.

Treating the wound

Contrary to earlier beliefs, tree paint and wound dressings don’t do any good. The US Department of Agriculture’s Forestry Service specifically advises against their use because numerous studies have shown that they don’t stop decay or prevent rot. Trees have been healing their own wounds for millions of years, and there’s no reason to interfere with this natural process

The right tools make all the difference

Second only to misunderstanding the how-to at tree pruning, is the confusion about what tools to use. Too many people figure that “wood is wood” and start pruning with either a roaring chain saw or a Carpenter’s saw. Or worse.

The results won’t be satisfactory, and you’ll likely damage the tree to boot. Using the right tools lets you make the cuts described in this story, and also reduces the level of effort. A modest investment (perhaps no more than $80) in shears and pruning saw, and rental as necessary for other tools, will let you properly maintain your trees.

When pruning small trees, the single most important piece at equipment is a pair of good-quality pruning shears ($25 to $50). Using this tool early in a tree’s life will greatly reduce the amount at corrective pruning that the tree will require as it matures. With the shears or a scissors-type hand pruner, you’ll be able to cut very close to the trunk. Position the thin blade of the shear on the trunk side to keep the resulting stub as short as possible. Shears are designed to cut branches up to 12 in. thick.

When you start having to twist and strain to make a cut, than you’re trying to cut too large a branch, and you need lapping shears (about $45 to $100). Loppers eon cut branches up to about 2 in. in diameter depending on the size of the blade opening.

Branches that are too large for lapping shears should he handled with a pruning saw. Never use a conventional shop saw — they require much more effort, the teeth clog quickly, and they do a poor job. Pruning saws are available in rigid and folding models, with straight or curved blades. For smaller branches, a curved blade is best because the saw cuts on the pull stroke. Large, straight-blade, rigid tree saws are used for larger cuts. Avoid saws with teeth on both sides at the blades

For higher branches, you have two choices — a good-quality step or extension ladder with someone anchoring it to the ground as you work, or it you feel uncomfortable or unsafe with this method, pale pruners are the answer. You can purchase them for from $70 to $120. There are two types available. One has a small curved tree saw at the end that can handle small as well as large branches; the other version has a cord- or rod-operated lever-action pruning shear at the end.

Be very careful when using the saw type of pole pruner an small branches, because it’s difficult to make a proper cut —— the branch will rip away, taking bark with it. To avoid this problem, use a pole pruner. Pole pruners are available in various lengths, but 8 ft. is typical. The poles can be made out of aluminum or wood, and are either one-piece or collapsible.

Never put yourself at risk. When dealing with large trees and branches, hire a professional. No tree is worth risking your life over.

Exercise extreme caution when using saws, poles or ladders near any overhead power lines. Also check so make sure that any branch you cut, or that may be ripped off when another branch is cut, won’t fall into an overhead power line. Call the utility company if there is any question about your safety in doing the work.