How to Prune Trees to Keep Them Healthy and Looking Tidy
Learn how to prune your trees the right way and at the right time of year to add beauty and longevity. Make sure you're making the right cuts in a safe and effective way.
Tree trimming has a way of stopping pruning newbies in their tracks. Frozen with a pruning saw in hand and eyeing up the tree in question, a host of questions begins running through your mind. Cut this branch? What about that one? Is this the right time to prune? What if I remove too many branches? Get the answers to all your questions so you'll have the confidence to add longevity to your trees and beauty to your landscape through smart pruning. Proper pruning technique is part art and part science. Once you know some of the science behind it, you can trust your eye for the artistic elements of pruning. Then, take a deep breath and start making your cuts.
Tree Trimming Safety
Approach every pruning situation by assessing the need for a professional arborist. Leave these tasks to the professionals who have both the equipment and advanced training for tricky pruning jobs.
- Trimming needed on trees near power lines.
- Removal of large dead or dangling branches.
- Large branches near homes or buildings.
When to Prune Trees
Late fall, after trees have shed their leaves, and early winter is a great time to prune. The bare branches allow you to see the tree structure clearly. Avoid major pruning during "maple sugar time" (January through early March in most areas). Beetles that infect oak trees are active from late spring through midsummer. If oak wilt is present in your region, don't prune your oaks during this period.
Prune away dead or diseased branches whenever you notice them. Waiting until fall or winter to prune these branches could cause further tree damage or infection in the case of diseased branches. (When pruning diseased branches, dip the pruning blade in a 10 percent bleach solution between each cut to avoid spreading disease.)
How to Cut Large Branches
Large branches are best removed in three steps:
- Make a shallow cut on the underside of the branch, about 4-5 inches from the trunk.
- Cut the branch off about 2-3 inches from the initial cut. When the weight of the unsupported branch causes it to fall, the initial cut keeps the bark from peeling down the side of the trunk.
- Make the final cut, removing the remaining stub. Make this cut just outside the branch collar: the slightly swollen area where the branch and trunk are joined together.
Game Plans for Pruning Challenges
Natural growth patterns, storm damage, and specific landscape needs can serve up unique pruning challenges. Find the situation that best describes your tree and sharpen your saw. It’s time to get to work!
Some trees naturally form narrow, V-shape junctures. While these narrow branch arrangements sometimes weaken the overall structure of the tree, not all require corrective pruning. Native elms, hornbeams, serviceberries, hickories, and Osage orange trees are generally strong enough or small enough that little corrective pruning is needed for structural purposes, except to remove crossing branches that might rub.
Other trees, particularly maples, flowering pears, ashes, and willows and basswoods, should be watched closely and given early training so they avoid structural problems as they grow larger. Narrow, V-shape junctures are inherently weak and are subject to breaking off in wind or ice storms. To prevent V-shapes from causing problems, remove one of the stems while the tree is young.
The following is a list of trees that tend to form V-shape junctures:
- Basswoods (Tilia spp.)
- Elms (Ulmus spp.)
- Flowering pears (Pyrus calleryana)
- Hackberries (Celtis spp.)
- Hornbeams (Ostrya spp. and Carpinus spp.)
- Locusts (Gleditsia spp. and Robinia spp.)
- Mulberries (Morus spp.)
- Osage oranges (Maclura pomifera)
- Redbuds (Cercis spp.)
- Serviceberries (Amelanchier spp.)
- Some ashes (Fraxinus spp.)
- Some hickories (e.g., Carya cordiformis)
- Some maples (e.g., Acer saccharum, A. saccharinum)
- Willows (Salix spp.)
- Zelkova (Zelkova spp.)
As a survival instinct, some trees send up new shoots from the ground. These fast-growing stems can weaken the main tree in time. Remove suckers before they are 6 to 12 inches tall by cutting them off at ground level. The best way to avoid annual suckering challenges is to avoid planting trees that commonly produce suckers. A reputable nursery or landscaper will be a great help.
Forked trunks are less stable than a single trunk and often grow together, leaving a hollow cavity where insects and rot can further weaken the tree. The tree will eventually split, or one of the trunks will break off.
To prevent this, remove one of the forked trunks while the tree is still young. Cut as close to ground level as possible, making the cut at a slight angle so rainwater drains off the stump. Take care not to damage the bark on the remaining trunk.
Too many branches bunched together can quickly weaken a tree. Small, weak branches limit the development of larger branches. Removing excessive branches, often growing laterally, will let the remaining branches get better air circulation and sunlight. This is especially important with trees that tend to form multiple branches at a single point on the trunk, creating a weak zone.
When a branch breaks off in the wind or is cut too far from where it joins the tree, a stub remains. Remove stubs as soon as they are noticed. A stub prevents a protective callus from closing the wound and provides insects with an entry point. Once insects make inroads, moisture and rot can take over. When cutting off an old stub, be careful not to cut into the swollen callus tissue forming near the trunk. It's needed to seal the wound.
You don't have to apply a seal over pruning cuts or broken branches. Allowing a wound to breathe is the best way for it to heal faster. Dressings sometimes prevent the growth of callus tissue (the swollen area) and may trap moisture that encourages rot. Most arborists now use tarlike wound dressings only for special purposes. Some insecticidal wound applications might be used, for example, to discourage beetles from visiting and possibly spreading oak wilt disease.