When Can You Trim Branches on a Maple Tree?

Spring Pruning Advantages

• Most shade trees, like the maple tree, respond best to trimming before buds open and trees leaf out in the spring. Pruning wounds will callus over, healing most rapidly during this time of year. There will be relatively few insects and disease spores present to potentially infect wounds due to cold weather. In addition, it is easier to see branches and make the correct cuts while trees are without leaves. Pruning in the late summer and fall can stimulate off-season growth, which in turn, can result in freezing damage to tender shoots. It will also remove nutrients stored in branches before they can reach the roots of the tree.

Sap Flow

• Maples, along with birches and elms, are often referred to as "bleeders" in the pruning context. Large limbs, approximately 3 inches or more in diameter, pruned during the spring can produce heavy sap flow. The sap will exude from the xylem at the pruning cut. The actual substance consists primarily of water, with a small amount of sugar and nutrients. It is the same substance that is used to produce maple syrup. Sap flow is tied to temperature. It only occurs when below freezing night temperatures are followed by warm days. This may occur anytime trees are dormant from October through April. It ends when buds expand, leaves develop and when night temperatures are continuously above freezing.

Pruning

• Avoid cuts that are flush with the trunk. Branch collar cuts, made at a 45-degree angle, will result in a much smaller wound. The branch collar is the slightly enlarged area at the base of the branch that holds the branch base, just beyond a noticeable bark ridge. In general, start at the highest point of the tree. Make clean cuts and avoid tearing bark as much as possible. Cut back dead branches until healthy wood is reached.

Pruning Need

• A healthy maple with good structural form, planted where there is ample room to grow, will need minimal pruning once established. In fact, too much pruning will reduce the tree's ability to generate food reserves through photosynthesis and could possibly weaken the tree. Provide annual pruning during establishment years to fix any structural problems present and create an attractive and strong framework. Once established, only prune select branches when necessary.