Animals that need food to survive the winter can take a toll on shrubs and young trees, but you can take simple steps to minimize the damage. Peter Linsner, who is in charge of controlling animal damage at The Morton Arboretum, offers these tips:
Check regularly for signs of damage. Voles, mice, rabbits, and deer may chew the thin bark of shrubs and young trees, and if they remove the bark all the way around a stem, it will die. Look around the base of the stems or trunk for signs that the bark has been nibbled.
Clear snow. If snow is deep around shrubs and young trees, mice and voles can tunnel through to reach the bark without being visible to predators. Clear snow away from the bases of especially vulnerable plants. When you’re shoveling after a heavy snowfall, remember that animals standing on the deeper snow can reach higher to browse on shrubs and trees.
Don't pile up mulch. Small animals also can tunnel through too-deep mulch. Spread mulch around a tree or shrub in a wide, even layer just two to three inches deep, and make sure it stays a couple of inches clear of the trunk or stems.
Fence vulnerable trees and shrubs. The best way to protect a plant is by fencing it with a well-anchored cylinder of metal mesh, Linsner says. That’s a lot of work, so think about the plants you need to guard. Rabbits are especially fond of certain species, including spirea, oakleaf hydrangea, and fothergilla, according to Linsner. Deer eat the winter foliage of many evergreen trees and shrubs, such as arborvitae and yews. They also eat the bark of young trees, as well as any twigs, buds, acorns, and berries they can reach. The Arboretum protects individual young trees with four-foot-high wire fencing in a cylinder that is two to three feet out from the branches, strongly attached to sturdy stakes. Deer still may nibble the tips of twigs, Linsner says, but as long as the central stem, or leader, is protected, it will recover. To keep deer out of the yard altogether, you’ll need an eight-foot fence, Linser says. Deer can jump anything lower.
Think about repellents. Animal repellents can keep deer and other animals from nibbling and damagining your plants. These products work by producing an odor or taste creatures dislike. Linsner emphasized the importance of reapplying a repellent after it rains or following a wet, heavy snow as melting snow can dilute the repellent.
No plant is animal-proof. "There are plants that animals don't favor,” Linsner says. “If there's plenty of food around, they'll leave them alone." Most of these plants have a strong odor, such as alliums, or a fuzzy or prickly texture, such as junipers. But if the winter is hard and food is scarce, rabbits, deer, and other animals will be less picky. You can find the Arboretum’s list of plants not favored by deer here, and the Plant Clinic also can help you choose animal-resistant plants.
Stay vigilant through this winter and, as you plan what to plant this spring, think ahead to make your garden a less attractive place for animals to dine.
For more tips on how to keep animals from damaging trees and plants, check out the Plant Clinic.