Preventing Winter Injury

January 12, 2017

Preventing Winter Injury in the Landscape

            The other night, for some unexplained reason, I got online and checked one of the weather websites that offers a 90 day forecast. Now I don’t put much more faith in a 90 day forecast than I do in the plan someone wants to sell me to help win the next lottery. But I do find that they might be giving us a general indication of the way things might develop this winter, even if they aren’t day-to-day accurate.

            What I found particularly interesting was, in the next 90 days, this website predicted our heaviest snowfall for our area to be less than three inches. Now I just know someone is going to come back and remind me of this when we’re belly deep in snow, but if this is anywhere close to accurate, it could provide some problems in and around our homes.

            Not having to deal with a lot of snow is something most of us welcome. While I never did, I find I enjoy scooping snow less and less as time goes on.  A lack of snow can be great for people and livestock, but it can cause injury to trees, shrubs and ornamentals. But there are things we can do to lessen the impact of an open winter in our landscape.

            A winter with little precipitation and no snow cover increases the risk of winter desiccation injury. We’ve had several winters recently with below normal snowfall. Often the result is woody ornamentals and perennials that fail to green up in the spring. Evergreen trees and shrubs are most susceptible, but lawns and perennials can also be injured. Tender and marginally hardy plants were hardest hit.

            One thing we can do to reduce this injury is to water plants when conditions are right. Winter watering can be done IF the ground is not frozen and the air temperatures is above 40OF. It is important to understand winter watering, because even rainfall or melting snow, can also cause plant injury. Be sure to apply water about mid-day so it has time to percolate into soil before freezing occurs night. Avoid excess watering so it does not pool around plant stems.

            If you decide to water this winter, make evergreen trees and shrubs your first priority. Marginally hardy plants should be second on your list. While all plants continue to lose moisture during winter, evergreens lose more moisture because their foliage is green all year. Evergreens don’t recover from the injury as well and may be more costly to replace if severely injured or killed. It is not uncommon for evergreens to turn light brown when spring arrives.

            The most common cause of spring browning is winter drying, not cold temperatures. The evergreens Arborvitae and Japanese Yew are most likely to sustain winter desiccation injury. Any evergreen grown in an exposed area, near pavement, or on the south side of a home is also more susceptible.

            Correct summer and especially fall watering, before the soil freezes, is important to prevent winter desiccation on evergreens. But if dry, open conditions persist, watering should continue during the winter months. Again, only water when the soil is not frozen, air temperatures are above 40OF, and at mid-day so water soaks into soil and does not pool and freeze around plant crowns at night.

            For valuable plants grown in exposed sites, a physical barrier made of burlap, weed barrier fabric, or snow fencing can still be installed to provide protection. Anti-transpirant sprays could also be applied according to the label. Mid to late winter is often when the majority injury due to desiccation occurs, so continue to water this winter and early spring if dry, open conditions persist. 

            For more information on preventing winter drying injury in your landscape, contact your local Nebraska Extension office.