Japanese maples, known botanically as the Acer palmatum species, are ornamental trees and shrubs grown for their colorful foliage and graceful, lacy canopies. Japanese maples are relatively slow-growing and do not require regular annual pruning to maintain their health and form when grown in the landscape. According to the University of Florida, the tree looks best when it is not pruned to control the size. Removal of damaged wood and light grooming to show off the trunk or form are the most common reasons for trimming the species.
Remove broken, cracked, discolored, diseased, abrading or dead wood and foliage by pruning back to a point of healthy wood or down to the parent branch or limb. Place the cut just outside the slightly swollen branch collar using secateurs for twigs and stems, loppers for small-diameter wood and a fine-toothed pruning saw for larger diameter wood.
Showcase the trunk and understory of your Japanese maple by trimming a few of the lower branches away to expose more of the tree architecture if desired. Prune according to your eye and cut each lower branch all the way back to the trunk or parent limb to preserve the natural form and flow of the remaining branches. Conduct this pruning carefully, considering each cut before making it, as the tree will be slow to restore its form, if ever. Never remove more than one-third of the branches in any pruning session.
Trim back any branches on cascading or weeping forms of the species that actually come into the contact with the ground soil. This can be a highway to transport disease and insects. Weeping branches should hover over the lower soil but not touch it. Prune back the branch tips to just above a leaf node or remove the branch back to its parent.