Low temperatures, frost or dry conditions are all causes of winter injury. In our region we can expect one or all of these conditions during the winter months. The results of these conditions vary from leaf burn to the death of the entire plant.
Causes:
Low temperatures: If the temperature drops below a plants ability to tolerate it, this is known as low temperature injury. Generally this occurs in plants which are not suited for a particular zone. Frost cracks or sun-scald occurs when temperatures drop after the bark has warmed up. Symptoms of low temperature injury include branch or stem die-back, black or brown leaves, or splitting of the bark.
Frost: Injury from frost occurs during the late fall or early spring when plants are still growing. If temperatures drop below or near freezing, this is when frost injury will occur. Symptoms of frost injury include brown to black flowers, fruit or leaves.
Dry Conditions: This is also known as "winter burn". It occurs when the leaves of the plant continue to lose moisture, which is not replaced. Generally plants in exposed sites to the wind in the winter are more likely to have this damage occur.
Although these are the 3 most common injuries to occur in winter, there are other problems that can occur. If there is a heavy snowfall or icy conditions occur (freezing rain), these can cause limbs to break. Food is scarce during the winter months for such animals as deer, mice and rabbits. They will seek out leaves, bud and bark to supplement their winter diets.
Solving the problem:
There are certain steps a homeowner can take to lessen the chances of winter injury. The most important step is choosing shrubs and trees that are hardy for the zone you live in. Check with your local nursery if you are unsure of the zone you live in. Ensure your soil drains well when choosing an area in which to plant. Give your trees and shrubs a good soaking before the soil freezes in the fall to ensure they have sufficient moisture for the winter months. Use some sort of windbreak for trees and shrubs in exposed areas. Good maintenance throughout the growing season by providing nutrients, water, and protection against stress to ensure your plants are more resistant to winter injury.