How to Prune Ash Trees Safely

Ash trees can take a hard hit from one bad pruning job. The wrong season, a torn branch, or a climb without proper gear can leave lasting damage. When learning how to prune ash trees, start with timing, inspect the tree first, then remove only what needs to go.

For most Northern Utah ash trees, early spring or the period after September is the safer window. The steps below will help you handle light work and spot jobs that belong with a trained tree crew.

We pulled the USDA APHIS emerald ash borer dataset, which lists confirmed infestations in 38 states plus the District of Columbia. A Utah State University Extension fact sheet caps yearly removal at 20 to 25 percent of live canopy and flags dieback from summer cuts. Utah’s own firewood quarantine requires wood entering the state to be heat treated to 160 degrees Fahrenheit for 75 minutes before it can move. With EAB confirmed in 39 jurisdictions nationwide, the 25 percent canopy cap, cooler-season timing, and keeping ash wood on site match the current data.

Step 1: Choose the Right Time to Prune an Ash Tree

Good timing lowers stress on the tree and can reduce the chance of pest activity around fresh cuts. Plan light pruning for late winter or early spring, before strong new growth begins.

Research on ash pruning points to early spring and the period after September as the best windows. That goes against the common idea that summer is always safe. Hot Utah weather can add stress while the tree is already trying to move water through its canopy.

In Northern Utah, watch the local weather before you pick a day. Avoid pruning during extreme heat, drought stress, or a sudden cold snap. If the tree is actively struggling, first deal with the cause. That may mean poor watering, root damage, a pest issue, or a disease problem.

Start by removing dead or dying wood. This is a safety task, but it also helps limit places where decay and disease can spread. General ash tree guidance places dead and dying branches first for both tree health and public safety.

Do not treat timing as a fixed date on the calendar. A higher-elevation site may warm later than a sheltered yard in the valley. Our seasonal pruning guide for Northern Utah can help you compare the tree’s condition with the season before you cut.

If emerald ash borer is known in your area, ask a tree professional about local treatment guidance before moving wood. Timing helps, but it does not replace a pest check.

Step 2: Inspect the Tree and Prepare Safe Pruning Tools

Before learning how to prune ash trees with a saw, inspect the whole tree from the ground. Look for dead limbs, hanging branches, cracks, loose bark, trunk wounds, mushrooms near the base, and branches that press against a roof or utility line.

Check the ground, too. Soft soil, exposed roots, fences, sheds, parked cars, and play areas can change how a branch must be lowered. A branch that looks small from the ground may swing wide when it comes down.

For light work on a small tree, gather tools that fit the branch size. Use a small cutting tool for small twigs, loppers for medium branches, and a pruning saw for larger limbs. Keep each cutting edge sharp and clean. A dull tool can crush bark instead of making a neat cut.

Use appropriate protective equipment when overhead branches could fall. Keep other people and pets out of the drop zone. Never prune near power lines unless the utility company or a qualified professional has made the area safe.

Do not climb while using powered cutting equipment. Do not use ladders beneath large limbs. Professional climbing requires specialized equipment and a plan for lowering wood. Some climbing methods can injure the living layer beneath the bark, which gives pests and disease an easier entry point.

Our tree health assessment service is useful when the signs are hard to read. We look at the tree, its setting, and the risks below the canopy before choosing a pruning plan.

Stop the DIY job if you find a large dead limb, a cracked union, trunk decay, storm damage, or any branch that needs climbing. The safe choice is a trained crew with appropriate equipment.

Step 3: Remove Problem Branches With Correct Pruning Cuts

Correct cuts remove the branch while protecting the trunk. In most cases, start with dead wood, then deal with broken, rubbing, crossing, or poorly placed branches.

Find the branch collar before you cut. The collar is the slightly raised area where the branch joins the trunk or a larger limb. Make the final cut just outside that collar. Do not cut flush against the trunk, and do not leave a long stub.

For a larger branch, use a three-cut method. First, make a shallow undercut a short distance from the final cut. Next, make a top cut farther out to remove most of the branch. Finish with a clean cut just beyond the collar. This keeps the falling limb from tearing a strip of bark down the trunk.

Pruning guidance warns against topping and explains why large limbs need a planned sequence of cuts. Topping leaves stubs and can lead to weak new growth.

Use the natural shape of the ash tree as your guide. Remove a branch because it is dead, unsafe, diseased, or likely to cause a structural problem. Do not cut healthy limbs simply to make the crown look perfectly even.

Skip covering pruning wounds in ordinary pruning jobs. A clean cut and good timing are usually better than covering the wound. If disease is suspected, pause and get a diagnosis before cutting more wood.

Never move ash firewood or pruned branches without checking local rules. Emerald ash borer can spread when infested wood travels. If you must keep wood for firewood, follow local instructions for cutting and drying it.

A branch that is too large for your saw is too large for a casual backyard job. At that point, lowering the limb matters as much as making the cut.

Step 4: Shape Young and Mature Ash Trees Without Overpruning

Shaping means guiding growth, not stripping the crown. Young ash trees need small corrections that build a sound structure over time.

For a young tree, select one main leader when the form allows it. Keep branches that attach at stronger, wider angles. Remove branches that compete with the leader or crowd the same point on the trunk. Leave temporary lower branches when they protect the trunk and do not block a walkway or road.

Space permanent branches up the trunk instead of leaving several major limbs at one level. Branches that grow too close together can compete for room and may create weak unions later. Make small cuts while branches are young. That avoids removing a large limb years later.

For a mature ash, focus on clearance and weight balance. Raise the canopy only as much as needed for a driveway, roof, sidewalk, or view. Thin selected interior branches if the crown is crowded, but do not strip out all inner growth. The tree needs enough foliage to make and store energy.

Stay below 25 percent of the live canopy in one year. If the tree needs more work, spread the job across seasons. Removing too much at once can cause stress and trigger a flush of weak shoots.

Young trees may need follow-up checks as new shoots grow. The goal is to catch a branch that starts competing with the leader before it becomes a large problem. Our young tree pruning guide explains that lighter corrections are easier on the tree than late heavy cuts.

Do not copy a pruning pattern from another species. Ash trees have their own growth habits, and a mature tree may need a different plan than a newly planted one. When the crown needs major reshaping, an ISA-certified arborist can mark the branches before the crew begins.

Step 5: Clean Up, Monitor the Tree, and Know When to Call a Professional

Good pruning ends with a clean site and a follow-up check. Gather every branch and twig from the work area. Do not leave ash wood stacked beside another ash tree, especially when pest activity is a concern.

Look at the tree again after the cut. The remaining crown should still have a natural outline. Check that no stub remains, bark has not torn, and the trunk has no fresh damage from falling limbs or equipment.

Monitor the tree through the next growing season. Watch for new dieback, thinning leaves, bark cracks, small holes, unusual shoots, or sawdust-like material near the trunk. A single symptom does not prove emerald ash borer or another disease, but it does justify a closer look.

Call a professional when the work involves height, heavy limbs, power lines, a narrow drop zone, storm damage, or signs of decay. The same applies when you cannot tell whether a branch is dead or when the tree has lost a large part of its crown.

All Wood’s Tree Service, Inc. helps Northern Utah homeowners, HOAs, property managers, and commercial clients with trimming, removal, stump grinding, and emergency cleanup. Our crews can match the method to the site, whether that means hand work on a small tree or heavier equipment for a high-risk job.

We also assess disease concerns before recommending removal. In some cases, injection treatments, meaning targeted chemicals applied through the trunk, may be part of a care plan. In other cases, removal is safer for the property and nearby trees.

We provide free estimates and 24-hour emergency cleanup for urgent tree hazards. All Wood’s Tree Service, Inc. has served Northern Utah since 1995, and we aim to be your long-term property care partner, not a crew that rushes through a cut and leaves you with the next problem.

FAQ

When is the best time to prune an ash tree?

The best time to prune an ash tree is usually early spring or after September, when conditions are cooler and pest activity may be lower. Avoid heavy pruning during hot, dry weather. Check the tree first, because drought stress, disease, or active pest damage may need attention before routine shaping.

How much of an ash tree can you prune at once?

Remove no more than 25 percent of an ash tree’s live canopy in one year. Light cuts are safer than a major crown reduction. If the tree needs more work, spread the pruning over later seasons or hire an arborist to set a staged plan.

Can I prune an ash tree in summer?

You can remove an immediate hazard in summer, but summer is usually a poor time for heavy ash pruning. Heat and low water can add stress, while fresh cuts may raise pest concerns. Limit summer work to urgent deadwood or storm damage unless a qualified professional recommends more.

Should I move ash branches after pruning?

Do not move ash branches or firewood without checking local pest rules. Infested wood can help emerald ash borer spread to healthy trees. Keep cut material on the same property only when local guidance allows it, and ask a tree professional how to handle suspect wood.

When should I hire a professional to prune an ash tree?

Hire a professional when the ash tree is large, near power lines, over a structure, or damaged by a storm. You should also get help when the trunk shows decay or the tree needs climbing. Professional crews have the gear to lower limbs safely and protect the property below.

Conclusion

For a small ash tree, prune in a cool season, remove dead wood first, and make each final cut just outside the branch collar. Stop when the job involves height, heavy limbs, decay, or power lines. If you’re unsure, request a free estimate from All Wood’s Tree Service, Inc. so we can inspect the tree and suggest the safest next step.

Ready to put this into practice? All Wood’s Tree Service, Inc. was built for exactly this.