This is an article readdressing an issue that many homeowners faced last year. We had a very hard winter for many of the evergreens listed in this article. I am hoping for a milder winter, however there are never any guarantees! For the sake of helping you save your evergreens this winter, we are visiting this issue again.
Evergreens are wonderful additions to our yards. They offer four seasons of interest because of their ever green needles which are really modified leaves. Because of the fragile nature of these beauties, it is important we do our very best to care for them. Proper care will help you avoid winter burn. Winter burn, the browning or death of evergreen needles or leaves, is caused when the leaves or needles dry out and die.
There are four primary reasons winter burn occurs:
- New growth that has not had a chance to harden off is especially sensitive to sudden, extreme temperature drops in early fall or late spring. Injury or death may occur to this tender new growth.
- Wind and the winter sun cause excessive water loss from the leaves while the roots are not able to replace lost water due to frozen soil.
- Bright, sunny, winter days can warm leaves which can cause cellular activity. As leaves become shaded, foliage temperatures can quickly drop below freezing. This sudden temperature drop can lead to foliage injury or death.
- The chlorophyll in the needles can be destroyed (photo-oxidized) during sunny, cold winter days. Chlorophyll cannot be reproduced when temperatures are below 28° F which causes the leaves to become bleached.
Winter burn damage typically occurs on the south or southwest facing sides and where evergreens that experience the most wind. Yew, arborvitae, hemlock, and newly planted evergreens are most sensitive to winter burn. Often, people may confuse this type of damage as a disease or damage from extremely cold winter temperatures. More often, winter burn damage occurs during warm weather in late winter and early spring.
A few other reasons winter burn occurs are salt and salt spray coming from products commonly used to de-ice walkways and streets. The hot air blowing from heat vents and dryer vents can also be problematic. Planting too late in the fall can also increase winter burn because roots do not have proper time grow, causing poor water uptake by the plants. Planting after mid-October can become risky for root development.
There are several ways to minimize winter damage to evergreens. Most importantly, plant evergreens in the best locations for their well-being. Avoid planting on south, south-west or windy exposures to minimize winter burn. Covering or constructing a barrier of burlap or similar material on the south, southwest, and windswept sides of evergreens, especially on newly planted trees, can help minimize damage. If an evergreen is fully exposed on all sides, surround it with some loose covering like burlap leaving the top open to allow for some air and light penetration. Anti-desiccant sprays may also be helpful in reducing water loss through the leaves. Follow all directions on the label for the health of your tree.
Proper watering throughout the growing season and into the fall is another way to reduce winter injury. Water evergreens slowly and deeply by letting the hose trickle for half an hour or so near the base of the plant once per week. Take care that you are not creating more plant stress by over or under watering. Continue watering until the ground freezes.
If an evergreen has suffered winter injury, damaged foliage and branches can be pruned out in mid-spring. Healthy buds may grow and fill in areas where there was brown foliage was removed. If the buds are also dead, branches can be pruned back to living tissue. Fertilize plants in early spring and water them well throughout the season. Make note of problem areas and provide appropriate protection the following winter.
Best practices will offer greater success for you. Best practices include covering newly planted evergreens with some type of breathable fabric, proper plant maintenance, proper plant selection, and proper plant placement. Following these guidelines will help increase your chances of minimizing winter damage to your evergreens. Giving your plants the proper care and maintenance will keep them happy for years to come.
– Deb, Treelot Manager