Pruning Deciduous Trees and Shrubs in Winter
By Robin Haglund
When plants are resting for winter, leaves have fallen, and branching structure is unclothed, pruning is easier on the plant and on the person pruning. Knowing how to make cuts, where to make cuts, when to cut, why to cut (or not to cut), and what tool to cut with are key in optimizing our pruning practices and plant health.
Before you decide to prune your twiggy winterized shrubs, it is important to know when it will bloom. Many bare-branched beauties are already filled with tightly held flower buds for spring. If you cut them off in winter, they won’t bloom for another year. Witch Hazel, Flowering Winter Currant, Forsythia, and Viburnum may offer bare winter branches, but better to prune them right after they bloom in spring instead.
Every pruning class I teach begins with a basic overview of how plants grow, which impacts how they react to pruning cuts. Tip buds on branches control how the rest of the stem grows. If we chop off those tip buds randomly, we can cause plants to flush out with new growth – in all the wrong places. These tipping or shearing cuts can be very detrimental to the overall health and safety of our trees and shrubs. * Instead of chopping randomly on branches, it is important to remove branches to points where they connect to other branches or trunks. Take care not to cut into the raised collar or ridge at the point where branches meet; this collar is important to tree’s ability to cope with pruning disturbances.
I prefer to use sterilized, sharp bypass hand shears and pruning saws to prune. If your hand shears aren’t big enough to make a clean-cut, use your hand saw instead. If you can’t reach, use a pole saw. For big trees requiring the pros, be sure to find a certified arborist who climbs using ropes, saddles and ladders. Climbing spikes will damage your trees.
Before you start cutting, evaluate the plant for basic clean up requirements. Look for dead material, broken branches, suckers, water sprouts and branches that are crossing or rubbing. Begin by clearing out all of the dead material, which will allow you to see the plant’s structure more clearly. Then, remove broken or torn branches, followed by suckers, water sprouts and rubbing/crossing branches. Always keep an eye on the volume of living material you have removed from the plant, never taking off more than one quarter (older, bigger plants) to one third (younger plants) within one growth year.
Once you have completed the basic clean up, step back and evaluate the project for shape; remove branches as needed, but don’t exceed the maximum annual removal total. Pruning for shape is usually what we want to do first; it should be what we do last.
And please, never cut the top off the plant in an attempt to make it shorter; cutting this way will simply cause the plant to send out all sorts of ugly shoots that get even taller, bushier, and will make for more intensive work in years ahead. “Topping” a tree this way will make your plant weak, ugly and potentially a hazard. If your plant is too big for your space, consider replacing it with the right, size appropriate plant for that place.
*Shearing some hedges, when done correctly (and not in the dead of winter) can be desirable.