Talking Plants 

Jillian Patrie | University of Minnesota Yard and Garden Extension

January and February tend to be the coldest months, with plenty of wind and snow.  Though it doesn’t seem like there would be any plant care tasks, pruning is something gardeners can do this time of year.  Let’s look at the does and don’ts of winter pruning trees and shrubs.

Why prune in the winter?  In some cases, this is the best time to prune, especially for tree species that are susceptible to disease and insects.  During the winter months, these pests are not active, which makes spreading them less likely.  The lack of leaf cover also makes it easier to see where pruning cuts need to be made.

Apple trees are commonly pruned during the winter months; this is done before bud break in spring.  In the Red River Valley, apple tree pruning can be done from March to the end of April in a typical weather year.  Avoid REALLY cold temperatures when pruning.  Shade trees can also be pruned this time of year to avoid disease movement, oak, elm, ash and chokecherry would all be good candidates.  What about evergreens and shrubs?

Shrubs such as dogwood or spirea can be pruned in the winter, encouraging a healthy spring flush.  Heavy pruning of evergreen trees during the winter months should be avoided.  Spring flower shrubs like lilac and forsythia should be pruned in the late spring, immediately after blooming has finished.

Using proper tools and techniques are important while pruning trees and shrubs.  Sharp, clean pruners will ensure a clean cut that the plant can close, avoiding issues down the road.  If you are pruning a plant that has a known disease, make sure to clean any tools used to avoid spreading bacteria, fungi and insects to other plants.  The way a pruning cut is made matters too.  When pruning trees, never cut flush against the trunk, make sure to cut outside of the branch collar.  Cuts need to be clean, do not leave behind jagged areas, “stumps” or torn bark, these can make it challenging for the tree to close the pruning wound. Keep pruning balanced, it’s best to only remove up to ⅓ of the plant height at one time.  Over pruning can cause a lot of stress to woody plants and may invite unwanted disease and pests during the growing season.  Large trees can have structural issues when the weight is not balanced, leading to failure during extreme weather events.

To learn more about how to prune trees and shrubs visit https://extension.umn.edu/planting-and-growing-guides/pruning-trees-and-shrubs.  Make sure to check the University of Minnesota Extension’s YouTube videos on pruning apples too!  If you are interested in an in-person apple pruning workshop, visit z.umn.edu/AP26 to register for the Moorhead workshop on April 23rd.

For local assistance or questions about this article please contact Clay County Extension Educator Jill Patrie at 218-299-7338 or by email at patri350@umn.edu.