Winter burn is a common evergreen problem that happens during the winter, but doesn’t become visible until around March when temperatures start to increase. Winter burn occurs when the evergreen plant loses water through its leaves faster than the root system can replace the water. This process of losing water through the leaves is called transpiration. When transpiration occurs and the roots can’t take up enough water, the leaf tissues are damaged.
Watch out for winters where the temperatures warm up and then drop again rapidly. When the warm temperatures occur, the plants need to have enough moisture in the soil to replace the natural transpiration process. If the soil is dry when it’s above freezing and then the temperatures drop dramatically, it’s likely damage will be done.
How do you prevent winter damage? Water broadleaved evergreens in the fall during dry spells, especially those that are newly-planted. You may need to water once or twice during the winter when the ground is thawed, more regularly if the plants are in containers. Broadleaved evergreens are especially susceptible to winter burn.
Besides excellent watering in the fall and mild winter days, another preventative measure is to apply anti-transpirants that prevent water loss through the leaves. A common brand found at most garden centers is “Wilt Pruf”, but there are several excellent products on the market. This product would need to be applied a few times throughout the winter since it washes off after a couple of rains/snows. Contact your landscape maintenance provider if you’d like to get a treatment scheduled for your plants.
It’s March and the Winter Burn has already happened?
What to do now? Give the plants a good soaking. Let the damaged leaves drop, they will be replaced by fresh leaves soon. For evergreen perennials such as hellebores or epimedium, remove the old damaged leaves and stems, taking care not to cut off the newly emerging leaves and/or flowers.
If the entire shoot looks dead, scratch the stem with your fingernail. If it is green beneath the bark, it is still alive and may send out new leaves. If it looks dry beneath the bark like a toothpick, then the shoot is probably dead. Regardless, wait a few weeks to see where new growth emerges before you prune out dead shoots, or pull out the plant. Unless you are an experienced gardener, it’s best to wait until mid-or late April before pronouncing the patient dead.