Willows grow quickly, and fast growth comes with weak wood. That makes pruning more important for willows than for many other trees. Good structure when young means fewer broken limbs later. Weeping willows also need regular trimming to keep their long branches off the ground, the roof and the people walking underneath.

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The short answer: prune willows in late winter while they are dormant, or in summer after the spring flush of growth. The Morton Arboretum recommends pruning white willow in summer to late fall. Avoid heavy pruning in spring while leaves are expanding. Remove dead, broken or diseased wood at any time. Focus pruning on young trees to build a single strong trunk with wide-angled branches.

When to prune

Time	What to do
Late winter (dormant)	Structural pruning, removing crossing and competing branches; easy to see the framework without leaves
Spring, during leaf-out	Avoid major cuts
Summer to late fall	The Morton Arboretum’s recommended window for white willow; trim weeping branches, remove water sprouts
Any time	Dead, broken, diseased or hazardous limbs

Like many fast-growing trees, willows can bleed sap from late-winter cuts. That does not harm a healthy tree.

Prune young willows for structure

The University of Florida IFAS Extension says all willows need initial pruning and training when young to develop a strong, central trunk with branch unions that are as wide as possible. UF IFAS notes weeping willows are prone to breakage at the crotch due to poor collar formation, and that their wood itself is weak.

For the first five to ten years:

Keep one main leader. If two stems compete, remove or shorten the weaker one.
Favor wide angles. Remove branches that form tight, V-shaped unions with the trunk; those are the ones that split later.
Space the main branches. Aim for scaffold branches spread along the trunk, not all from one point.
Raise the crown gradually. UF IFAS notes weeping branches droop as the tree grows and need pruning for clearance. Remove the lowest limbs a few at a time over several years.

Trimming weeping branches

Weeping willow branches can reach the ground. Many people like the curtain effect; others prefer to keep a clear path underneath.

Cut hanging branch tips back to a side shoot or bud at the height you want, often 6 to 8 feet above the ground for walking under.
Make cuts where they will be hidden in the foliage, not in a straight horizontal line.
Do this in summer, when you can see where the leaves hang.

Mature willows

For mature trees, the International Society of Arboriculture advises removing only what is needed and generally no more than about a quarter of the live crown in a year. Priorities on a mature willow are:

Dead and broken branches, which are common after storms.
Branches with cracks or weak unions, especially over the house, driveway or play areas.
Crossing or rubbing branches.
Water sprouts, the fast, upright shoots that often appear after pruning or damage.

Don’t top willows

Topping, cutting large branches back to stubs, is especially harmful on willows. They respond with a burst of weakly attached shoots that grow quickly and break easily, making the tree more hazardous. If a willow is too big for its spot, the honest answer is often removal and replacement with a smaller tree.

Pollarding and coppicing: a special case

Some willows are traditionally pollarded (cut back to the same knobs on a short trunk every year or two) or coppiced (cut near the ground) to produce flexible stems for weaving or colorful winter twigs. This must be started on a young tree and repeated regularly. It is not a way to rescue an overgrown mature willow.

Pruning out disease

UF IFAS lists willow scab, black canker and other canker diseases that kill back shoots. The recommended response is to prune out infected branches. Make cuts in dry weather, well into healthy wood, and clean tools between cuts. Rake up fallen diseased leaves in fall.

Making good cuts

Cut just outside the branch collar; do not leave stubs or cut flush.
Use the three-cut method for heavy limbs to avoid tearing the bark.
Do not paint or seal cuts.

Clean up after pruning

Willow twigs root easily when they touch moist soil, so rake up prunings rather than leaving them on damp ground near ponds or ditches. Diseased branches should be removed from the site, not composted. Healthy prunings make good mulch once chipped.

When to hire a professional

Large willows are often brittle and sometimes hollow. Work above head height, with a chainsaw, or near power lines belongs with a certified arborist. The ISA Find an Arborist directory lists professionals by area.

If your willow is dropping leaves, see why a weeping willow loses leaves. Planting a new one? Read how far a willow should be from a house.

Sources

Salix babylonica: Weeping Willow (ENH-734), University of Florida IFAS Extension
White Willow, The Morton Arboretum
Pruning Mature Trees, International Society of Arboriculture, TreesAreGood.org

Top photo: Richard Avery, CC BY-SA 4.0, via Wikimedia Commons

When to Prune a Willow Tree