Pruning Japanese Maples: Timing and Technique

Japanese Maples are among the most forgiving trees to prune, but they are not immune to poor timing or careless cuts. The goal of pruning is to reveal and refine the tree's natural structure, not to impose a shape on it.

When to Prune

Late winter is the ideal window for structural pruning. The tree is fully dormant, you can see the branch structure clearly, and wounds callus over quickly once growth resumes. In the Pacific Northwest, late January through mid-February is generally right, before buds begin to swell.

A secondary opportunity exists in midsummer, after the initial flush of growth has hardened off. Light thinning at this point reduces density without stressing the tree. Avoid pruning in spring when sap is actively rising, or in fall when you want the tree to slow and harden before winter.

What to Remove

Start by removing anything dead, damaged, or diseased. Then look for branches that cross or rub against each other, and remove the weaker of the two. Next, take out any growth pointing straight up through the canopy or straight down toward the ground. Finally, step back and consider whether the overall canopy is balanced.

As a general rule, never remove more than 20 to 25 percent of the canopy in a single session. Japanese Maples can be slow to recover from heavy pruning, and overthinning leads to a flush of weak, congested regrowth.

Tools and Cuts

Sharp bypass pruners for stems under half an inch, a sharp pruning saw for anything larger. Make cuts just outside the branch collar at a slight angle. Clean tools with rubbing alcohol between trees if disease has been present.

Wound sealants are generally not recommended for Japanese Maples. The tree seals its own wounds best when cuts are clean and correctly placed.