When winter weather turns abnormally frigid or freezes heavy ice on tree branches, there’s not a lot a gardener can do but salvage what’s left. But some winter damage can be minimized and even prevented by a taking a few important cold-preparation steps in fall. One of the most important – and widely overlooked – measures is keeping the soil damp until it freezes. Depending on your region and each year’s weather variation, that can happen sometime between late October and early December.
Most gardeners know it’s important to water plants in hot, dry weather, but many then put away the hose soon after Labor Day. That can be a problem during dry autumns when plants and roots are still growing. Water demands go down as growth slows and daylight diminishes, but it’s still possible to stress or even kill plants from lack of water in the fall. This is especially important for new plants added in the past year or two – ones that haven’t fully rooted and are most dependent on consistent moisture near the original root ball.
Adequate fall soil moisture also is especially important to broadleaf evergreens, such as cherry laurel, osmanthus, aucuba, camellia, sweetbox, boxwood and holly. Evergreens not only need soil moisture while they’re still growing in fall, but unlike trees and shrubs that drop their leaves in fall, they keep losing moisture through their leaves all winter. Needled evergreens, such as spruce, fir and pine, also run into this issue but not quite as much as evergreens with wider leaves.
When the ground freezes in winter, evergreen roots can’t replenish the moisture being lost through their leaves. If it gets cold and windy enough, plants begin to suffer from “windburn” – a condition in which the foliage first browns around the edges, and in bad enough cases, browns all over. In severe cases, the plant can drop leaves or graduate from winter-burn to dead. To prevent windburn, plant broadleaf evergreens – especially borderline winter-hardy ones – in wind-protected areas, such as courtyards or along the east side of a fence or house.
Then don’t be too quick to put away the hose for winter. Soak the ground every week or two throughout fall if the soil is dry, up until the ground finally freezes regularly. In warm regions where the ground doesn’t freeze, keep the hose handy all winter. You won’t have to water as much or as often as summer, but just because the calendar says winter doesn’t mean plants need no water.
A third windburn prevention is wrapping tender, borderline-hardy or wind-exposed plants with burlap. Pound a few stakes around your plants, and staple burlap sheets to make a windbreak or that goes all around the plants. Stuff the burlap protector with leaves or straw to buy a little extra insulation.
Some professionals recommend spraying evergreens with anti-transpirants (a.k.a. anti-desiccants). These are resin, latex or wax sprays that coat leaves and block their openings in an effort to slow winter moisture loss. However, most field studies show anti-transpirant sprays have little to no effect in preventing winter damage and are more useful when used in transplanting plants during hot weather.
Another helpful winter-prevention strategy is making sure 2 to 3 inches of mulch cover the ground around your trees, shrubs and perennials. Wood chips, shredded hardwood, pine straw and bark mulch are all fine. So are all of those leaves that are dropping from trees in fall. They’re nature’s plant insulation. Mulch helps keep moisture in the soil, keeps the soil warmer longer, and prevents the see-saw freezing and thawing that can shove young plants partly out of the ground, exposing their roots to killing cold and wind. Some people even pack mulch 6 inches or more against the trunks of grafted roses, figs, crape myrtles and similar tender plants to help keep buds low on these plants alive during a super-cold winter spell. That’s usually a gardening no-no, but if you limit it to woody plants and pull back the extra mulch first thing in spring, you may do more good than harm. Two increased risks of mulching up on the trunks: rotting the bark and giving a safe haven to bark-gnawing rodents.
Fall is a good time to test the soil for nutrition and add a granular, slow-acting fertilizer such as GreenView with GreenSmart Fall Lawn Food sometime before the ground starts to freeze. This provides nutrients as grass plants head into dormancy and are then already in place in the root zone when growth resumes first thing in spring.
Finally, don’t overlook winter animal damage. Deer eating foliage, rabbits girdling young tree trunks, and voles eating the roots out from under shrubs and perennials all can be more damaging than any winter storm. Wrap the trunks of young trees and shrubs with paper or plastic tree wrap to prevent animal chewing or protect trunks with a cylinder of wire or hardware cloth around their perimeter. Gardeners in deer country may need to erect a tall fence around the whole yard or at least around plants that deer favor. An alternative (or addition) to fencing is spraying vulnerable plants with one of the many scent and taste repellent sprays available at most garden centers.