The snow has finally arrived, offering spectacular vistas and providing a covering blanket for ground-cover-type plants and other species of plants with shallow root systems or crowns that are partially exposed, such as day lily or sedum. The snow provides shelter and protection from the drying winter winds that can wreak havoc on foliage of evergreen type ground cover, preventing severe moisture loss and die back. Most gardeners are grateful for the help that snow provides. But snow cover can be a double-edged sword, since when it provides cover for the plants, it also provides cover for garden pests that are active all year, most commonly mice and voles, which use snow cover to search for food.
During the spring, summer and fall months, these pests forage for food using the cover plants provide to keep them out of sight of the predators that feed on them, primarily hawks, falcons, owls and snakes. Snakes hibernate during cold weather, so they are not a danger during the winter, but birds of prey are still active. Snow provides the cover mice and voles need during the winter. While these pests are considered omnivorous, they are usually almost totally herbivorous during the winter months.
Though mice sometimes travel on top of the snow, they much prefer to travel under it. Creating tunnels under the snow, these pests can travel from one landscaped area to another without being detected. These tunnels are actually channels that the pests chew through the grass to create a pathway. They scurry along unimpeded and safe. They can do serious damage to plant material, especially ground cover shrubs such as juniper. They chew the bark off the branches, causing severe dieback. The extent of the damage depends on the number of animals involved and the length of time the snow cover remains.
Don’t despair or discard plans to install plantings that may attract these pests! With the use of traps and bait you will be able to reduce severe damage. Use mousetraps with bait such as peanut butter or spread warfarin pellets throughout the planting. Ensure that foliage does not reach the edge of the bed but leave a four- to six-inch buffer of bare soil, and place traps in that area. The damage caused by these pests is not readily apparent, but one tell-tale sign is the sinuous channels devoid of any grass detectable as soon as the snow melts. If you see these, check your plants, lifting the branches to check for chewing. If it is still winter and you have not yet taken any preventative measures, it is not too late. You can still set traps or scatter pellets. If you miss signs of damage during the winter months, you may find your plants dying back during the summer for no clear reason, as mouse and vole damage can take a while to kill foliage.
Another animal that can do a lot of winter damage is the rabbit. Cute but not friendly, they are lazy feeders in that they won’t dig for food but will sit on top of the snow and chew the bark off branches. Damage can occur from ground level to any height and is readily noticeable, shiny white ends of branches with rabbit droppings nearby. Control methods vary, from the extreme of shooting them to less violent hot pepper spray. There are only a few plants that escape their incessant chewing, though mature trees are rarely damaged. The nursery industry reports serious loss of income due to rabbit damage, amounting to billions of dollars yearly.
The home landscaper or gardener can discourage rabbits by putting up barriers made of woven chestnut or hazel branches, twelve- to eighteen-inches high and 48 inches long. These are pleasant to look at and store well in the garage or garden shed. Chicken wire is also a useful protective material, though somewhat less attractive to look at!
The other small mammal that plagues gardeners, the mole, is largely inactive during the winter months, especially when the ground freezes. So winter brings a respite for the gardener from at least one critter!