Many of your perennials survive winter without extra care but winterizing is an important step in ensuring colorful flowers in the spring. For tender plants and new additions to the garden, winterizing is vital for cold weather survival.
What causes winter damage?
Cold temperatures, ice/snow, wind, salt and animals can all cause considerable damage to your trees, shrubs and perennials.
Most perennials are cut back after the first hard frost in the fall. This usually occurs in late September or early October. It is important to clean off all plant debris after the frost to help minimize soil-borne diseases.
Most perennials simply need a good layer of mulch applied late in the fall. The purpose of mulching is to protect the crowns of the plants from the alternate freezing and thawing that occurs very late in fall and in early spring. It is important that the ground be allowed to get cold before mulching, so wait until early to mid-November before covering the plants.
When you add fall mulch, aim for a layer that’s 3 to 5 inches deep (deeper in colder regions). Use a material that won’t compact, like straw, chopped leaves or cornstalks, pine straw or clean hay. It’s especially important to mulch shallow-rooted perennials that are prone to frost heave.
Clear out leaves, before applying mulch. Trimming perennials and cleaning up leaves will avoid future garden problems such as insects, slugs and snails, and powdery mildew on roses and apple trees. Weeding in the fall will help to limit the weeds that will grow back in the spring. You can add all this garden debris to your compost pile for future use; remember to avoid using diseased material.
Even on the coldest winter day, the sun can reflect off the snow onto landscape plants and warm the tissue enough to thaw; then the sun sets and the temperatures drop, freezing the plant tissue again. On young trees, this alternate freeze/thaw cycle can causes vertical splits in the bark on the trunk. This is a problem on most young trees, but is most common on maples.
You can wrap the trunks of susceptible trees and prevent almost all splitting. You simply start wrapping around the base of the trunk and work your way up as far as you can reach or to the lowest branches. You can also get plastic tubes that can be slipped around the lower section of the trunk, but they can leave too much of the trunk exposed.
Rodents and deer can do extensive damage to trees and shrubs as they forage for food during the winter. Rodents can be kept from gnawing on trees by encircling the base of the trunk with 1/4″ gauge hardware cloth or screen wire. The wire cylinder should be tall enough to extend at least a foot above the deepest expected snow. Try using repellents as well.
When it is windy and sunny in the winter, evergreen foliage can lose moisture that it cannot replace with the ground frozen, resulting in browning. To help minimize this browning, be sure your plants have been well watered all season, right up until the ground freezes. Avoid planting evergreens in a windy location where they receive the direct afternoon sun in the winter.
To protect these species from browning, wrap the plant with a loose-weave burlap.
While there are some varieties of plants that are tolerant of low levels of salt, nothing will withstand very much. In fact, salt can actually be used as an herbicide. Avoid planting where salt will be used or where there might be salt runoff.
Keep the salt off greenery with a barrier made from 2×4 stakes and erosion-control fabric—the fine mesh won’t let salt seep through.
Ice and Snow
Evergreens can be damaged by heavy snow or ice buildup. On trees such as spruce, the branches will usually bend and recover. Plants with upright branching such as arborvitae and junipers, can split and break.
Wrap tall, narrow shrubs in a tight column with twine to keep branches from collecting heavy snow or ice and breaking off.
Shelter plants up against your home from falling icicles and snow melt with a simple, reusable A-frame structure that you can make from 2x4s and exterior-grade plywood.