I always talk about pruning evergreens after a hard freeze. Why? With the cold, borers and bark beetles are no longer flying ready to attack trees. Since every pruning cut is a wound and these insects are attracted to the chemical signals sent out from wounds, we can avoid insects infesting and weakening trees, particularly drought-stressed trees. That being said, what is a hard freeze anyway? According to weather.gov, a “Hard freeze occurs when the temperature reaches 28 degrees or lower for at least a few hours.” We have experienced a hard freeze here in west Washoe Valley, but not every area has. My husband and I are ready to prune. If it got down to 28 degrees or lower for a few hours where you live, it is now safe to prune pines, spruces and other evergreen trees. Although evergreen trees usually need little pruning, here at home we have a lot of pruning to do for a number of reasons. The blue spruces along the drive have grown so tall and full that they are scraping the RV when we come and go, which totally annoys my husband. You may have heard the phrase “Happy wife, happy life.” Well, the same applies to husbands, although I can’t make it rhyme! There are pine tree branches scraping the ground and making it hard for my spouse to mow. Those have to go. Some pines and spruces have dead branches to be removed. I’m hoping we can prune a layer off the incense cedars to let more sun onto our walkway to reduce the ice in winter. A couple of spruces need lower branches pruned to allow easier access to a gate out to the field. An Arizona cypress is so large, it’s blocking the decorative boulders I paid a fortune for 30 years ago. A little shaping and pruning and the cypress will look good and I will see my rocks too. When pruning evergreen trees, avoid pruning the main leader. Make sure your tools are clean and sharp. Never make a “flush cut” right up into the trunk, which creates a permanent open wound encouraging internal decay and insect infestations. Always cut to the outside of the branch bark collar, which looks like the lowest knuckle on your thumb nearest the palm. With this cut, the tree can close up the wound. For information on pruning evergreens: https://static.colostate.edu/client-files/csfs/pdfs/618.pdf. And, for additional information on proper pruning cuts: https://static.colostate.edu/client-files/csfs/pdfs/613.pdf. The Arbor Day Foundation has a great video library on tree care: https://www.arborday.org/trees/video-library.cfm. JoAnne Skelly is associate professor & extension educator emerita for University of Nevada Cooperative Extension. She can be reached at skellyj@unr.edu.
