Pruning Woody Trees and Shrubs

A common mistake homeowners make is waiting too long to prune woody plant materials. Don’t wait until you have a problem on your hands! Prune trees and shrubs as they mature; training them for shape and habit. Some things to look for when deciding whether to prune are: crossing or rubbing branches, narrow crotches, trees with multiple leaders, and damaged stems and limbs. Keep interior branching clear so that sunlight and air can penetrate the interior of plants. Trees and shrubs compartmentalize their wounds. So the smaller the pruning cuts, the quicker and easier it is for the plant to recover and care for itself.

When pruning avoid: stump cuts, cutting into the collar and use of any pruning sealants. If a stump is left behind when pruning, the stump will rot away, which is a great entrance point for insects and disease. If a pruning cut is made too close to the collar, the pruning cut can damage the main branch and the wound will not be able to close up completely. This results in a weak point for insects and disease. In the past it was believed that a fresh pruning cut should be made impenetrable with a pruning sealant to prevent sap from leaking and to aid in compartmentalization. Using these types of products should absolutely be avoided because they can actually seal in bacteria, leaving no exit point. Release of sap or ‘bleeding’ following larger pruning cuts can be unsightly; however it does not injure plant materials. When larger branches are removed, they should result in a donut shaped scar at the point of removal. This is how one can be assured that it was pruned away at the proper distance from the remaining branch or trunk.

Always use the right tool for the right job and keep those tools clean, especially when moving from plant to plant. Main hand tools are pruners, loppers, and hand saws. Pruners are the best tool for making cuts which are 3/4” or less in diameter. Loppers work best for cutting branches 3/4” to 2” in diameter. Branches with larger diameters should be pruned using a hand saw. Make sure your pruning equipment is properly sharpened to ensure that the cut is smooth and clean. It is important to avoid leaving crushed or rough pruning cuts because they will not properly close up. Keep tools sanitized to avoid spreading disease from one plant to another.

As a general rule, winter dormancy is the best time to prune most deciduous trees and shrubs. This gives you the opportunity to view the branching structure to see what branches need to be removed. However, there is always an exception to the rule. Early spring bloomers such as lilacs, spirea, and forsythia should be pruned immediately following their bloom. Semi-woody perennials or perennials which have hollow stems, such as hardy hibiscus and Russian sage, should not be cut back until mid spring. Snow and moisture can find their way into these hollow stems if cut back too soon and cause crown rot, killing the plant. Evergreen shrubs should be pruned in early spring before active growth begins and light pruning can be done in the summer. If pruned too late into the fall, soft new growth is susceptible to winter injury. Prune evergreen trees, such as spruce and fir, when they are still dormant in late winter; pines should be pinched in early June to early July.

Woody trees and shrubs provide the bones and structure of our surrounding landscapes. We are reaching the optimal time for pruning before buds break dormancy, so get out in your winter garden and prepare for the upcoming growing season! Gardeners start to get very antsy this time of year because we can start to see hints of spring right around the corner. It’s almost here…!

-Alyssa Eyman