by Patrick Leitch
In the late winter months when temperatures have the potential to drop into the single digits or below zero for days or even weeks, plants can be susceptible to winter burn. It may not be noticeable until plant tissue begins to come out of dormancy and the damaged parts are unable to recover to normal function and turn yellow or orange. And damage like this means it is too late to salvage those branches or whole plants.
What can we do to prevent this?
Covering plants is an option, however this can be cumbersome.
You could apply an anti-desiccant; this can be costly.
Would you consider watering in sub-freezing temperatures? Well, most people may avoid this option thinking that it would cause damage potentially due to the already freezing conditions, however the opposite is true.
Proper winter watering is a safe and effective means to helping our plants. If the plant or planting is fairly new (within a few months) the soils in the root zone will be fairly loose still and could dry out more readily. Root damage from frozen dry air is the cause for most winter death in plants. This is even more common in high winds and unprotected areas. Therefore, watering in the winter when the concern is warranted should be a consideration.
Now, ideally the air and soil temperatures should be at or above 40 degrees. Watering the soil zone within the drip line will be enough to keep the roots hydrated and warm. The well-hydrated soil will insulate and keep the ground from freezing as quickly or as deep. So, when the temperatures and flow through the end of the winter look for 40 degree opportunities to protect those at-risk new or wind break plants with supplemental water. The Colorado State University’s Extension published that woody plants with shallow root systems require supplemental watering during extended dry fall and winter periods. These include European white and paper birches; Norway, silver, and red maples; lindens, alders, hornbeams, dogwoods, and willows. Evergreen plants that benefit include spruce, fir, arborvitae, yew, Oregon grape-holly, boxwood, and Manhattan euonymus. Woody plants also benefit from mulch to conserve soil moisture.