One of the many reasons we love evergreens so much is because they’re a steadfast source of life and color during the cold months. They don’t normally require much attention compared to the rest of your garden, so it’s easy to assume they don’t need any extra protection. Although your evergreens are hardy enough to endure the worst of winter in the Quad Cities metro area, that doesn’t mean they enjoy it. A little extra TLC will lessen the potential for damage, allowing them to maintain good health through the season.
Winter Burn on Evergreens
The biggest threat to your evergreens over the cold months is winter burn. It might sound a little contradictory for trees to “burn” in the winter rather than summer, but the cold, dry air is actually much more damaging.
We already know that plants absorb moisture from the soil through their roots. That water is stored in the plant’s foliage—this gives conifer needles their rigid structure. Plants also release moisture through evaporation, which is necessary for many plant processes. This entire cycle of water movement is called transpiration, and it happens to all kinds of trees.
The key difference here is that conifers hold onto their needles all year long, which means they’re continually transpiring, even when they’re dormant. Not only do the harsh conditions of the cold season, like bright sun, dry air, and strong winds increase this rate of transpiration, but the frozen ground also means there isn’t much water available to absorb. When trees lose moisture faster than they can restore it through their roots, they become dehydrated, leading to the browning effect that we call winter burn.
Identifying Winter Burn on Evergreens
Luckily, winter burn is pretty easy to spot and simple to avoid. The first and most obvious sign of a dehydrated evergreen tree or shrub is the discoloration of its foliage, turning bright green leaves and needles an unpleasant shade of yellow, rust, or brown—as if we needed more dull shades this time of year!
The burn works it’s way inward, starting at the tip of the needles and working down towards the base, or starting at the outer margin of broadleaf leaves and moving toward the center. Similarly, the discoloration will begin on the outer branches and slowly make its way to the trunk if the tree isn’t protected.
Of course, many things can cause discolored leaves and needles. The best way to determine if your tree has a cold burn problem is to take note of which side of the tree is most exposed to the sun and wind—if the damage is worse there, then it’s probably due to burning. Keep in mind; prevailing winds here in the Quad Cities metro area are from the west from November to February and from the north from February to April.
Tips for Protecting Your Evergreens for Winter
Understanding how harsh temperatures and winds can affect our lovely snow-covered landscape can help us take measures to prevent damage. Adding just a couple of extra steps to your fall gardening routine will make a world of difference to your evergreens. Here’s how to protect them from winter damage:
Give your plants a deep watering, just before the ground freezes. This goes for all the plants in your garden, but is especially helpful for supporting your coniferous foliage. Keeping on top of fall irrigation will ensure your plants’ roots drink up as much water as they can, creating a good water supply for themselves before the ground freezes.
Mulch your evergreens in the fall. Some of you may already know the benefits of mulch during spring and summer, but did you know that mulching is equally important in fall? Similar to how it locks in moisture and protects your plant’s roots from the hot summer sun, a good layer of mulch will also help to regulate soil temperature and retain moisture during the snowy season. Mulch delays the ground freeze happening underneath, giving roots a little extra time to soak up some more moisture.
Wrap your more fragile evergreens with burlap. Wrapping trees with burlap or canvas is especially crucial when protecting newly planted trees and smaller shrubs, as they’re a little more susceptible to harsh conditions. Not only does wrapping protect against burn, but it also prevents damage and breaking from strong winds, protects against road salts, and deters hungry pests from nibbling on bark and branches. Simply wrap the burlap around your tree, starting from the bottom and working your way up, and secure it with twine in several areas.
Use an anti-desiccant spray. Anti-desiccant sprays, also called anti-transpirants, are sprayed on conifers to form a protective coating over their needles. The coating affects the tree’s transpiration rates, minimizing moisture loss. Our favorite product here at Meyer is called Wilt Pruf. Unlike other products that use chemical polymers, Wilt Pruf is an all-natural spray made from pine oil. It’s non-hazardous and biodegradable, so you can be confident that it won’t affect the growth or health of your plant. You can even use Wilt Pruf to extend the life of your Christmas trees, winter porch pots, garlands, and holiday wreaths!
Treating Winter Burn
While the easiest way to control cold burn is by taking steps to protect your plants, sometimes damage from a particularly strong midwest storm is inevitable. Luckily, treating winter burn isn’t usually all that bad, as long as the affected branches are still alive. To check, scrape away a small patch of bark—if the plant tissue underneath is green, that means it’s still supporting growth. Just brush off the discolored needles and give your plant a healthy drink of water in the spring, and it’ll bounce back in no time!
If the branch is dry and lacks color after peeling some bark back, then it’s too late, and you’ll have to prune that branch off. Just make sure it’s not going to leave a gaping hole—some conifers, like pine, only support new growth at their tips and won’t replace a pruned branch with a new one!
Evergreens and Heavy Snow
Wet, heavy snowfalls are another danger to your evergreens. Unlike deciduous trees, evergreens keep their foliage all year, creating a “net” effect for falling snow. After a heavy snowfall, especially when the snow is heavy and sticky (the kind that’s perfect for making snowmen!), the snow can collect on branches and weigh them down. Heavy snow can accumulate on your evergreens enough to bend or snap off large branches. After a heavy snowfall, use the brush side of your window scraper to gently brush snow off your evergreens to prevent damage and help them keep their shape.
Just because they’re characteristically hardy, doesn’t mean your evergreens won’t find the freezing temperatures hard to handle. Although they’ll likely survive the season, they’ll definitely be a little worse for wear by the time the spring thaw finally happens. By equipping your evergreens for the cold, you’ll be keeping your landscape bright and green all year round.