When Is the Best Time to Trim Trees in the Pacific Northwest?

West of the Cascades, our mild wet winters and dry summers give trees a rhythm — and pruning at the right point in that rhythm makes a real difference. Here’s how the seasons stack up for the Seattle area.

Late winter to early spring — the sweet spot

For most trees, late winter through early spring, before bud break, is ideal. The tree is dormant, its structure is easy to read with the leaves off, wounds seal quickly as growth resumes, and there’s less disease pressure. This is when we do most structural pruning.

Summer — fine for light work and views

Summer is good for light pruning, deadwood removal, and opening up views once you can see the full leafed-out canopy. It’s also when many hazard issues become obvious. Avoid heavy pruning in a hot, dry stretch, which stresses the tree.

Fall — the season to be careful

Early fall is generally the worst time for major pruning: many decay fungi are releasing spores, and fresh cuts are prime infection sites. Save the big work for winter. Light cleanup is fine.

Anytime — safety doesn’t wait for a season

Broken, dead, diseased, or hazardous limbs should come off whenever you spot them, regardless of the calendar. A limb hanging over the driveway isn’t going to wait for February.

Special cases worth knowing

• Flowering trees (cherries, magnolias): prune right after they bloom so you don’t cut off next year’s flowers.
• Maples and birches “bleed” sap heavily if cut in late winter — not harmful, but many prefer to prune them in summer.
• Storm-prone conifers: thin before the fall/winter windstorm season so there’s less sail for the wind to catch.