From June thru July, you can prune up to 20% of the foliage on Japanese maples. You can also lightly tip-prune thru August to control new growth or runaway water. Save major pruning for winter when the tree is fully dormant. Do not prune after the leaf buds start swelling because the tree can bleed quite severely and become weakened.
All Japanese maples have “eyes” on the branches where the leaves are attached during the growing season. These “eyes” are small half-moon swellings, spaced every 1-3” along the Each “eye” faces a different direction, rotating along the branches.
Pruning ¼” above a particular “eye” will make the tree branch out in that direction the following You can control the shape and direction of the tree each year simply by deciding which “eyes” to prune above.
Avoid pruning beyond the previous year’s Always allow at least 2 “eyes” of new growth each year to remain on the tree. Pruning more severely can lead to knurled and stunted growth, with many tiny shoots coming out from same spot. If a large branch needs to be pruned to thin out the tree and allow more light, prune it completely off.