As your beautiful native maples drop their leaves and their branching structure becomes more evident, you may be tempted to perform some winter pruning. Generally, for deciduous trees, this would be the ideal time. When the trees lay dormant and the branches are more easily visible, it is very practical to perform the removal of dead, dying or interfering limbs. For maples, any pruning or wounds created during this period may cause an excessive loss of sap known as ‘bleeding’.
Although this bleeding is not fatal to the tree, and is mainly an aesthetic issue, it can be an open invitation for harmful pests and disease to feed on the sweet sugary sap. This coursing liquid is mainly composed of water and nutrients that travel up from the roots to feed the buds as they begin to swell in preparation for spring. This pathway from roots to buds is made possible by the vascular system. A network of conducting tissues that support the movement of water, dissolved minerals and food throughout the tree. The pressure of this upward movement through the tree’s vascular system is greater in spring than in any other time of year due to the rise of outdoor temperatures.
Unless you’re tapping sugar maples in the anticipation of making syrup, native maple trees are best left untouched throughout late winter and into spring. The best time for pruning a maple tree is in mid-summer, when the leaves have fully expanded and have turned a dark green. The exception would be the removal of any dead branches, which can be done at any time of year, or those that are of imminent threat to person or property. This time of year provides a great opportunity to view the branching structure and make plans for any future pruning needs. Placing a ribbon or tie on any branches that need to be removed or pruned back can aid as a reminder once the leaves have flushed and the branches are not as easily visible.
For more information about how to properly prune your maple tree go to:
Written by Caitlin Ayling, MLF Nursery Liaison and Andrew Cowell, MLF Arborist