It is important to take a few steps to winterize your broadleaf evergreens. Sometimes you will not be able to see the bad effects of winter on your plants until spring arrives and you see what has happened to your yard and garden plants. Very often a plant will seem to come through the winter with no visible signs of damage. It is only when you see the leaves with browning edges, and split bark in the early spring, that you realize that your plant has some major damage from winter kill. It is essential that you take precautions with yours shrubs and evergreens to get them winterized.
The cause of this is from a temperature imbalance. During prolonged cold spells a plant goes largely dormant. It will not take in moisture or let moisture out. On warm, sunny days in midwinter, such as during the traditional February thaw, the leaves may begin to transpire.
The roots are unable to replace the lost water while buried in the frozen ground. The plant becomes desiccated, as does many other broadleaved evergreens who are prone to this same condition. Rhododendrons, with their large leaves, are especially prone to this condition.
How to Prevent or Minimize Winter Kill
1.One thing that you can do, is to make sure your plants go into the winter season in a good healthy condition and place plenty of mulch around them.
2. The other thing you can do is to protect their exposed surfaces once cold weather sets in by coating them with an anti-desiccant spray. Apply the anti-desiccant spray when December temperatures are around 40 degrees, so that the mixture will be able to dry out properly.
*This type of spray will vary in effectiveness and may require respraying a second or third time. Be sure to read the labels and apply as directed. You should only apply the winter rate to the plant after it becomes dormant, not before.
This spray will sometimes be the one thing that will save your plants. There are many brands on the market. I have two anti-desiccants to suggest, 'Moisturin' and 'Wilt Pruf'.
3. Another way to reduce dehydration is to make a screen to block out wind, or completely cover your evergreen. If you may need to add stakes to hold up a wind screen made of burlap or plastic. Be sure to place the stakes into the ground before the ground freezes.
If you take care of your plants through the summer, they should do okay in the winter time. Avoid summer droughts that will quickly weaken your plants. Make sure they get enough water during the hot summer months.
Check the amount of mulch and replenish it so that it sufficiently protects the base and lower stems of the pant. Also, make sure you have no insect or disease problems.