When Can You Trim a Japanese Maple Tree?

Japanese maple trees are deciduous trees desired for their decorative seasonal foliage in shades of green, orange and red. Native to Asia, these trees grow in USDA hardiness zones 5 through 8. Over 300 cultivars are available in varying foliage and in heights ranging from 6 to 50 feet tall. Severe pruning is rarely needed, but you can trim a Japanese maple to encourage healthy foliage and maintain a graceful shape.

Use hand shears to trim off dead or damaged branches at any time of the year. Remove diseased or infected branches promptly. Trim these branches back to a main stem or branch. If branches are split with jagged wounds, cut the branch back to a fork or main branch. A clean cut heals more quickly than jagged edges. When the slender, arching branches reach the ground, trim these branches back to a main bud or branch inside the tree. Ground-touching damages branch tips and allows insects to travel into the tree.

Encourage a graceful Japanese maple canopy by trimming the tree in late summer. When the tree is in mature foliage, you can see the tendency for the tree to form leaf layers. Stand under the tree or inside the branches. Look for odd branches that run contrary to the layers. Remove these branches back to a main stem or branch. Trim out crowded branches so that air and light filter through the layers. Avoid trimming too early as Japanese maples are heavy weepers, quickly leaking out sap in spring. Though not usually harmful, the dripping branches are unsightly.

Choose late autumn or early winter for primary trimming. Autumn, when leaves are gone, is the best time to trim or prune the Japanese maple tree and remove errant branches. Trim out crossover branches. Remove branches that run straight up or straight out as Japanese maple branches are naturally curved. When two branches run side by side or parallel, remove one branch. Trim away any gnarled or scarred branches. Look for the branch layers and remove contrary limbs that grow inward instead of away from the trunk. Cut out deadwood. This is the opportunity to lift the tree skirt, trimming off branches that are spindly and hanging under the tree.

Trim cautiously. Japanese maples do not need aggressive pruning. They are non-invasive and respond well to trimming. Remove no more than 30 percent of the wood. Be careful in trimming foliage that screens the tree trunk. When the tree trunk is exposed to direct sunlight, it has a tendency to split open, encouraging disease and insect infestation.