How to Prune Trees Safely: Cuts, Timing and Tools

How to prune trees safely depends on the right cuts, timing and tools, so you remove the wood that causes problems and leave the tree able to heal.

A good pruning cut closes over within a season or two. A bad one stays open for years and lets in decay. The cut belongs just outside the branch collar, you should remove no more than a quarter of the canopy in a year, and anything that needs a ladder plus a power tool, or that sits near a wire, should go to a professional. This guide covers the cut itself, timing by tree type, tool limits, the safety rules for ladders, chainsaws and power lines, and the signs that a tree needs a certified arborist.

It belongs to the Trees guides. Pruning at planting time is covered in How to Plant a Tree Properly, flowering shrubs have their own calendar in Shrub Maintenance and Renewal Pruning, and the fruit-specific training is in Fruit Trees for Beginners.

Pruning trees safely at a glance

Safety first: ladders, chainsaws and power lines

More people are hurt pruning than cutting down trees, and most injuries come from falls, kickback and contact with wires. Decide what you won’t do before you pick up a saw.

• Ladders: set on firm, level ground at roughly a 1 to 4 angle (1 m out for every 4 m of height), with the top extending about 1 m above where you step off. Keep three points of contact, keep your belt buckle between the rails, and have someone foot the ladder. Don’t lean sideways to reach a branch; climb down and move it.
• Chainsaws: wear a helmet with visor, ear defenders, cut-resistant gloves, chainsaw trousers and boots with a steel or protective toecap. Use a two-handed grip, keep the bar tip clear of the wood to avoid kickback and keep the chain sharp. If you have never used one, take a training course before cutting anything that matters.
• Pole pruners: useful for reaching 3 to 4 m from the ground, but wear a helmet and eye protection, stand out of the drop zone and stay well away from lines.
• Drop zone: clear people and pets, and think about where the branch will swing as it comes down. Branches under tension from a bent neighbour can spring back.
• Conditions: don’t work in wind, rain, ice or fading light, and don’t prune alone if you can avoid it.

When to hire a certified arborist

A certified arborist (for example, ISA Certified in many countries) carries training, insurance and rigging gear, and can judge whether a tree is sound. Pay for one rather than improvise in these cases:

• The limb is thicker than about 10 cm (4 in), or heavy enough that you could not hold it at arm’s length.
• You would need to climb the tree, or stand on a ladder with a saw, to reach it.
• Any part of the tree, or the path of the falling wood, is within 10 m (33 ft) of wires, or over a roof, fence, car or neighbour’s property.
• The tree has been hit by storm or lightning, has hanging or cracked limbs, or has a sudden new lean.
• You see bracket fungi on the trunk, hollows, mushrooms at the base or a thinning crown, which may mean internal decay (see Tree Diseases: Identification and Organic Treatment).
• You’re considering removal, or the tree is protected by a local order or heritage rule. Check this before any cutting.

Ask for proof of insurance and certification, a written quote that names the work, and a promise not to top the tree. Be wary of door-to-door offers after storms.

Choose the right tool to prune trees by thickness

A dull tool tears bark and leaves ragged edges that heal slowly, so sharpen blades each season. Cleaning matters most when you move from a tree with fire blight, canker or silver leaf to a healthy one.

The three-cut method for pruning trees

If you saw straight down through a heavy limb from above, its own weight tears a long strip of bark off the trunk as it falls. Three cuts prevent that.

1. Undercut. About 30 cm (12 in) out from the trunk, cut a third of the way up through the underside of the branch. This stops the bark ripping.
2. Top cut. A few centimetres further out, saw down from above until the limb drops, leaving a short stub.
3. Final cut. Remove the stub just outside the branch collar. The collar is the ring of wound-sealing tissue; cut flush and you remove it, leave a long stub and the stub dies back and rots.

When to prune trees by type

Dead, broken or hanging branches can come out at any time, since they are a hazard. In subtropical and tropical climates there’s often no true dormancy, so prune after the main growth flush and avoid the hottest weeks and heavy monsoon rain. Palms are different: see Palm and Tropical Tree Care.

What to remove from a tree, in order

1. Dead, diseased and damaged wood. Cut back to healthy tissue with a clean blade.
2. Crossing and rubbing branches. Remove the weaker one of each pair.
3. Narrow forks. Where two stems of similar size join in a tight V, bark is squeezed between them (included bark) and the union can split. Remove one while it’s still thin.
4. Water sprouts and suckers. Remove them cleanly at their origin.
5. Low branches. Lift the crown gradually over several years, as a rule of thumb taking branches no more than about one third of the diameter of the stem they join.

Stand back after each few cuts and look at the tree from several sides. It’s easy to remove more than you meant to; it’s impossible to put wood back.

Why topping trees fails

Cutting main limbs back to stubs, often called topping or lopping, is the commonest pruning mistake. The tree responds with dense, weakly attached shoots that can break in wind, the large wounds seldom seal, and the crown has to be pruned repeatedly. If a tree is too big for its spot, the fix is a properly done crown reduction by an arborist (cutting back to side branches at least a third the diameter of the removed limb), or choosing a smaller species from Best Shade Trees for Home Gardens.

Troubleshooting after pruning trees

What pruning does to a tree

A clean cut just outside the branch collar lets the wound seal, while a flush cut removes that collar and encourages decay and canker. Sharp loppers and a pruning saw prevent torn bark, and disinfected blades stop fungus and virus from spreading between oak, maple and cherry. Winter pruning of apple and pear reduces disease pressure and improves light, but you should leave plum and cherry until summer because silver leaf spreads in wet weather.

Removing up to a quarter of the crown suits most mature trees, because heavy cuts force soft shoots that attract aphid colonies. Three cuts hold the weight of a heavy branch and stop bark stripping down the trunk. Why hire an arborist? Large limbs, power lines and ladders cause serious injuries, and a professional needs far less time than you’ll spend learning on a risky cut. Wound paint isn’t needed, since a good cut seals itself, and your extension service can explain timing for your species.

How the right cuts, timing and tools protect a pruned tree

A cut just outside the branch collar lets the wound seal in a season or two, while a flush cut removes the collar and encourages canker and decay. Sharp loppers and a saw prevent torn bark, and disinfected secateurs stop fungus and virus from spreading between cherry, maple and oak. Removing no more than 25% of the crown suits most mature oak and maple, because heavy pruning causes soft shoots that attract aphid.

Winter pruning of apple and pear reduces disease and improves light, while plum and cherry need summer cuts because silver leaf spreads through wet winter wounds. A three-cut method holds the weight of a heavy branch and stops bark stripping down the trunk of an elm or maple. Dead and crossing branches of birch and apple come out first, since they block airflow and host canker. Ladders and chainsaws cause serious injuries, so you should hire an arborist for limbs over 10 cm, anything near power lines or any job above 3 m. Wound paint isn’t needed on cherry or oak, because a clean cut seals itself, and your extension service lists timing for your species. The tree disease guide shows canker and fungus signs that pruning controls.

Sharp secateurs cut stems up to 2 cm, loppers handle up to 4 cm and a pruning saw suits branches up to 10 cm, so you’ll match the tool to the wood. Pruning in dry weather prevents fungus and canker from entering fresh wounds, and mulch around the base protects roots from drought after a heavy cut. Fertiliser high in nitrogen encourages soft growth after pruning, so you should hold off for 6 weeks. Birch and maple bleed sap in late winter, and that does little harm, but a vet or arborist can help if bark splits or the tree leans. Fruit trees such as apple and pear fruit better when light reaches the centre, and compost under the drip line feeds the new wood.

Pruning in late winter suits apple and pear, because dormant buds heal fast and frost damage on cuts is rare. A sharp saw and clean loppers reduce canker risk, and compost or mulch under the drip line protects roots from drought. An arborist can remove limbs near wires, and a vet can’t help a bird nesting in the crown, so check for nests before you cut in spring.

Common mistakes

• Flush cuts. They remove the collar and its healing tissue, so the wound stays open. Cut just outside the collar.
• Leaving stubs. A stub can’t heal because the collar is gone from the stub tip; it dies and rots inward. Cut back to the collar.
• Removing too much. More than about 25% of the canopy starves roots and forces weak regrowth. Spread the work across seasons.
• Wrong season. Winter cuts on plums invite silver leaf, and winter cuts on spring-flowering trees remove the flowers. Check the timing table first.
• Climbing up with a chainsaw. Kickback with one hand on a ladder is how serious injuries happen. Use a pole saw from the ground or hire a professional.
• Ignoring wires. Branches near lines conduct electricity and fall unpredictably. Call the utility or a line-clearance arborist.
• Dirty tools. Moving diseased sap from tree to tree spreads infection. Disinfect between trees.

Choosing the right blade makes pruning cleaner and safer, and Best Pruning Tools and Loppers compares secateurs, loppers and saws by cutting capacity.

Next steps

Put your pruned tree on a sound footing with Tree Watering and Mulching, learn to read cankers and dieback in Tree Diseases: Identification and Organic Treatment, and plan your seasonal jobs with Winter Garden Care. For the rest of the topic, return to the Trees guides.