Fall Pruning: What to Cut Now and What to Leave Until Late Winter

Fall is cleanup season. The leaves are down, the yard looks ragged, and it feels like the right time to get the pruners out. For most trees and shrubs it isn't. On the golf course, our big pruning push was in late winter, not fall, and there's a good reason.

Why fall is a bad time for most pruning

• Wounds close slower. In fall, plants are slowing down. Cuts made now sit open longer, and that's when decay fungi get a foothold.
• It can trigger new growth. A hard pruning in early fall can push out tender new shoots that don't have time to harden off before the first freeze, and they die back.
• You're cutting off next year's flowers. Many shrubs have already set their flower buds for spring.

Late winter is the sweet spot

For most deciduous trees and summer-flowering shrubs, the best time to prune is late winter to early spring, while they're still dormant but just before growth starts. Across most of the northern US, that's February into March.

Why it works:

• Without leaves, you can see the structure of the tree.
• Wounds start closing right away when growth starts in spring.
• Many insects and disease spores are inactive.

What's safe to cut in fall

1. Dead branches. Anytime. Dead wood is easy to spot in fall before the leaves are gone or right after.
2. Broken or damaged branches. After a storm, clean up broken limbs with a proper cut so the wound can close.
3. Diseased wood. Cut back to healthy wood and clean your pruners between cuts.
4. Branches that are a hazard: rubbing the roof, hanging over the driveway, blocking sight lines.
5. Perennials that had disease problems this year, so the disease doesn't overwinter in the debris.

What to leave alone in fall

Spring-flowering shrubs

These bloom on wood that grew last summer. If you prune them in fall, you cut off the flower buds:

• Lilac
• Forsythia
• Azaleas and rhododendrons
• Spring-blooming spireas
• Bigleaf hydrangeas (most varieties)

Prune these right after they finish blooming in spring.

Oaks

In areas where oak wilt is present, many extension services advise against pruning oaks from spring into summer, when the beetles that spread the disease are active. Late fall and winter is actually the safer window for oaks. Check your state's guidance.

Maples, birches, and walnuts

These "bleed" sap if you prune them in late winter. It doesn't hurt the tree, but some people prefer to prune them in early summer after the leaves are out.

Evergreens

Light shaping of yews and arborvitae is best done in spring or early summer, not fall.

How to make a good cut

• Cut just outside the branch collar, the swollen ring where the branch meets the trunk. Don't cut flush with the trunk, and don't leave a stub.
• Use the three-cut method on big branches: an undercut a foot or so out, a top cut just beyond it to drop the branch, then a final cut at the collar. This keeps the bark from tearing.
• No wound paint. Research shows it doesn't help and can trap moisture.
• Sharp, clean tools. Dull pruners crush stems.

When to call an arborist

Anything you'd need a ladder or a chainsaw above your shoulders for, or anything near power lines, is a job for a certified arborist. Look for ISA certification.

Fall jobs that do help

Instead of pruning, spend fall time on:

• Watering trees and shrubs before the ground freezes
• Protecting young trees from sunscald and rodents
• Mulching the root zone

Put the pruners away until late winter, and your trees and shrubs will come back stronger.

Photo: Tree Pruning by TreeMinion15, CC BY-SA 4.0.

Related: Planting Trees in Fall in the Northern US