The maple, or acer as it is know botanically, is a genus of deciduous trees grown for its richly colored fall foliage and for shade canopies. Maple trees vary widely in canopy shape and height with Ohio State University stating that the trees grow up to 100 feet tall when mature, depending on the species and cultivar. Many maple trees have symmetrical and beautifully shaped canopies and require no pruning, save the removal of dead or diseased limbs. Others with less uniform canopies can tolerate some trimming and shaping to reduce size with less harm to the form.
Trim your maple trees in the winter or early spring when the tree is dormant before bud break and any new growth has appeared. For maples that bleed sap when pruned, such as sugar maple, prune in summer to lessen the messy and unsightly sap flow.
Place all trimming and pruning cuts on branches flush against the trunk just outside of the slightly swollen berm of the branch collar to protect the wound site from disease and insect infiltration.
Trim back all dead, split, broken, diseased or otherwise compromised wood within the canopy. Place the cuts on the bias just below the damage into healthy wood. Pull the cuttings out of the canopy and burn, chip and compost, burn or otherwise discard them. Refrain from chipping and composting disease-laden wood.
Thin the interior of the canopy to allow sunlight penetration and airflow if it seems congested. Trim down all branches that cross and abrade one another to prevent damage and disease entry points. Place each cut on the bias down to a lateral or outward facing twig, branch or leaf axil or down to the parent branch.
Trim down the branch tips when absolutely necessary to prevent interference with utility lines, structures or other trees. Reduce the size of the canopy or alter the shape as desired, hewing as much as possible to the natural form of the tree. Remove no more than one-third of the canopy tissue in any trimming or pruning session to prevent stress and shock.