STOP! Don’t dig it up!
Despite that it looks rather devastating, turns out it’s best to wait when you have winter burn damage on conifers and other evergreens. The primary symptoms are needle/leaf browning, particularly on evergreens that are out in the open and not clustered with other trees. However, this is NOT an indicator as to the health of your conifer! The only way to tell is by selecting a section of stem and scraping off the outer layer of bark. If you find green inside and the stem to be supple, your conifer is going to be just fine. If, on the other hand, it’s brittle and dead, then you’re one of the few who are simply out of luck.
Plants that are likely to be affected:
- Schip Laurel
- Otto Luyken Laurel
- Manhattan Euonymous
Soo… Why does this happen?
Turns out it’s science! Evergreens are doing a whole lot more work during the winter than their deciduous cousins. Since their leaves (or needles) are still green, they are still photosynthesizing all Winter long. Photosynthesis requires water, sunlight & carbon dioxide. So as evergreens take in CO2 and create O2, the leaves/needles are using water. Normally evergreens draw water up through the roots to replace what is used in the process of photosynthesis + what water evaporates through the leaf/needle membranes and the cycle of photosynthesis continues. However, during winter months where the ground is frozen, water may not be readily available and thus, the strategy (and only option) for the evergreen is to allow their leaves/needles to die and preserve what little water they have left. The result, as I mentioned before, looks rather devastating… brown, dead-looking needles/leaves that are dry and brittle. Often due to the severity of appearance, winter burn is misdiagnosed as a disease, when it is actually more likely for the plant to make a full recovery!
Prevention & Treatment
Prevention: It’s as simple as pouring hot water on the frozen ground at the base of your conifers on a bi-weekly basis while temperatures remain below freezing. The idea here is that the hot water unfreezes the ground temporarily and allows your evergreens to drink until it freezes up again. Some people have also reported success with placing a thick layer of hay with mulch on top around the base of your evergreens for the winter to insulate the ground around them. In extreme cases you can also wrap evergreens in burlap to shield from wind during winter storms.
Treatment: There are of course some steps you can take to treat winter burn. Two methods in particular seem to be the most effective.
- Trim dead sections down to the point where you scrape the bark off and find green underneath
- Wait for new growth to begin and allow the evergreen to shed it’s dead leaves naturally
It is important to make sure that your evergreens are properly fertilized and watered after a Winter burn event. Subsequent unfavorable conditions (such as a hot, dry summer with little water) can further weaken your plants and make them more susceptible to disease and increases the chance they will not survive a second round of Winter burn the following Winter.