Too soon to start pruning evergreens
University of Nevada Cooperative Extension
I’m just itching to start pruning our evergreens, but my arborist self knows it’s a bit soon. I will wait until we have a hard freeze, to ensure my pruning cuts won’t attract any bark beetles. When a tree is pruned, we actually are wounding it. This causes the tree to release chemical signals that can attract beetles to infest the weakened tree. However, beetles are no longer active after freezing weather.
I‘m waiting for temperatures to drop to 27 degrees or lower for a long enough time to kill back sensitive plants. Since I’m certainly enjoying these gorgeous fall days and autumn colors, I will control myself and wait a little longer before pruning evergreens.
Most evergreen trees need little pruning other than occasional shaping. Any dead, diseased or damaged wood should be removed. With diseased plants, be sure to disinfect tools with isopropyl alcohol so you don’t infect healthy wood on the same plant or on other plants. I prefer isopropyl over a bleach/water mix because it doesn’t damage tools and is easy to carry in a spray bottle.
Before pruning, make sure your tools are sharp, clean and disinfected. Sharp tools make good cuts without damaging branch tissue. Since every pruning cut is a wound to the tree, it’s important to keep the wound damage to a minimum. At the base of each limb where it connects to the trunk is a “branch bark collar,” which allows a tree to compartmentalize and close up the wound. Remove a branch back to the trunk just outside of the branch bark collar. Do not injure the branch bark collar, or the cut will never callus over and the tree will always be susceptible to diseases and pests. Do not make flush cuts up against the trunk.
Remove a branch in the three-cut method: Make the first cut an undercut 12-15 inches out from the trunk, one third to half way through the branch. The second cut occurs on top of the branch a couple of inches out past the first cut, removing the branch. This initial double-cut method prevents the weight of the branch from tearing the branch bark and tissue below the branch bark collar into the trunk. With the final cut, remove the rest of the branch carefully, just outside the branch bark collar. Avoid pruning the central leader.
Evergreen trees and shrubs should be pruned according to the species growth characteristics. Timely pruning means healthy plants.
JoAnne Skelly is Associate Professor & Extension Educator, Emerita, University of Nevada Cooperative Extension. She can be reached at firstname.lastname@example.org.