How to Shape and Train Japanese Maples

With its dramatic coloring and versatility in shape and size, it's no wonder the Japanese maple (Acer palmatum) is a favorite for landscapers and homeowners who want a little low-maintenance beauty in their yards. The slow-growing tree is relatively small, reaching around 15 to 20 feet high, and responds to and even benefits from training and shaping. Although minor pruning can be done almost any time of year, any major shaping should be done during the tree's winter dormant season.

Japanese maple

Pruning tools

Bleach

Water

Bucket

Wire (if bonsai)

Decide on your shape. Do you want to maintain the tree's natural crown shape? Are you trying to train a bonsai? Deciding ahead of time what you want your tree to look like will prevent mistakes. As the Japanese maple is a slow-growing tree, any major mistakes you make will be visible for a long time.

Disinfect your tools. Prepare a weak (roughly one part bleach to ten parts water) solution. Dip your blades in. This will prevent your tree from becoming infected when you prune.

Start pruning and shaping. Prune the dead leaves and branches first. Prune away the branches that are crossing over another or overcrowding or that are damaged or otherwise weak. Take away the branches that are growing at angles too close to the tree's main leader or trunk; they will eventually crowd out other branches and compete for air and light. Prune the crown to your desired shape.

Don't prune branches too closely to the main branch or leave long stubs that will just die. If you're pruning a tree in an area where there's a lot of traffic, prune away branches that may get hit or damaged by passersby. This will prevent wounding that could result in breakage or stripping and lead to infection.

Pinch leaves back during the growing season to encourage the regrowth of smaller leaves, a technique you might want to consider if training bonsai. When training bonsai, wire the trunk and branches to your desired shape.