Preparing Your Trees for Winter

Jesse Fulbright, MSU Liberty County Extension

As much as I hate to admit it, leaves are beginning to fall slowly from the trees and gardeners are wrapping up their harvests.  Doesn’t it seem like winter was just here in April?  As we prepare for autumn now we need to be thinking about how to prepare our perennials, especially our trees for the long winter ahead.

During a normal autumn, as leaves fall off and temperatures drop, transpiration, or the loss of water from plant tissues, also falls off, most of it occuring through the stomata and epidermal openings on shoots and leaves.  Water loss therefore is minimal in the fall under normal conditions according to the Montana Master Gardener Handbook.  The low rate of transpiration, coupled with low temperatures, allows plants to harden and enter dormancy to survive the winter.  A normal recommendation for trees and shrubs, especially for conifers, is to water throughout the fall until the soil freezes.  Fall watering fills the plant’s reserves for use during the winter months.  Watering also reduces desiccation of shoots and foliage, and because the plants are dormant, doesn’t stimulate new growth. 

Photo courtesy of University of Illinois Extension

Everything I just mentioned is true for a normal autumn.  However, if we have a warm autumn, continued watering may keep less hardy trees from hardening off.  Therefore, you have a tree that is not prepared for those icy blasts of fall and winter when they do come.  However, withholding water from conifers may make them more susceptible to sun scald, which is just a fancy term for winter desiccation.  Overall, recommendations from M.S.U. Extension is to reduce, but don’t stop, watering in the fall.  Conifers are the exception to this as they still need water going into the winter. 

Continuing to speak about the conifers in our yards, they need attention during the winter when we get those warm spells or chinooks.  Evergreen trees and shrubs should get watered during these warm spells to help them with the winds and south and western sun aspects.  However, avoid heavy watering as this could stimulate early growth, especially under warm conditions.  We would like all the trees to break dormancy naturally and not be fooled into breaking dormancy when there is still more winter ahead. 

If you need further information about how to prepare your yards, trees and shrubs for winter I would encourage you to contact your local county Extension office.