Winter Preparation
Cold weather events can do just as much damage as a heatwave, but there are several things you can do to protect your garden in winter weather.
Winter Preparation Tips
Moist roots are much more durable in cold weather than dry roots! Often, our coldest weather comes with dry air and clear skies, oftentimes with high winds. Moist soil is a better insulator than dry soil, so please make sure the soil around your plants is moist during cold weather events. Even if the water in the soil freezes, it is still better off moist.
Kale, chard, onions, garlic, and shallots are fine if left uncovered. Lettuce and other greens, broccoli, and cabbages should be harvested or protected with row covers, frost blankets, or cold frames.
Heavy snow or ice can cause branches on some conifers (e.g. arborvitae and junipers) to bend down under the weight, or to splay. Tying twine in a spiral shape, like a candy cane, around the length of the tree before snow arrives can help prevent this. The twine should be removed in spring when danger of harsh weather passes.
Cold winds are our biggest foe in winter. Wind desiccates needles and branches, sapping moisture. The hardiest of plants can sustain winter wind damage. Apply Wilt-Stop to newly planted, evergreen plants to help keep leaves and needles moist during drying winter winds.
Plants in pots are considered to be tender and should be brought into a cool room of the house, like a garage, for the duration of the most extreme temperatures. Citrus, cactus, Gardenia, Bougainvillea, and tropical jasmines are all in this category. Don’t forget to check for pests before bringing them out of the garden!
Move containers close to the house, preferably in a spot that is protected from cold winds. Make sure your geraniums, fuchsias, and other tender plants are tucked away for winter.
Insulate your pots. Many products—like frost blankets and burlap—can be used for insulation. Using old sheets or blankets will work fine too, but avoid using plastic to cover plants, as it will increase moisture while limiting air circulation. Adding straw or leaves under frost blankets will increase protection.
Plants are warmer in the ground than they are in containers. It’s a good idea to increase warmth for anything that is on the border of hardiness by adding mulch and covering plants with frost blanket, burlap, or old sheets. Hebe, New Zealand flax (Phormium), Camellia, and star jasmine are all in this category.
Some people like to cover or wrap their plants during cold snaps. This is fine and can temporarily trap a little bit of heat, but the key word is temporarily. Again, the plant is not making body heat to replace any lost heat. It does have the advantage of keeping some of the wind off of the plant, reducing damage from wind chill. Covers and wraps should be temporary and should not be used during our ordinary chilly, drizzly winter weather. They can trap moisture on the plant and can encourage rot.
Roses and other plants that may be overgrown can be partially cut back now. This is primarily to keep the plants from whipping around in the winter wind. In the case of roses, the actual pruning should be done in February before new growth starts. Some trees and shrubs like to be cut back now, while others prefer late winter (for some, either is fine).
Lay mulch before the cold weather settles in. A layer of composted garden mulch or bark helps to protect the shallow roots in soil from being damaged by freezing air temperatures. It acts like a blanket, trapping some of the heat in the soil while keeping the soil temperature above freezing—even when the air temperatures are temporarily below it.
Please note, neither soil nor plants actually make body heat as we do, so the blanket effect is only to trap existing heat, not continue to make and hold heat the way we do in our beds. It is alright for the mulch to partially cover most perennials, but it should not bury the wooden stems of trees or shrubs. During extended cold snaps, the soil can still freeze—but there is little you can do about this or the possible damage that can happen to plants. Remember, deeply rooted plants such as established trees and shrubs should have no problems with this; it is never cold enough for long enough here to truly freeze the earth like in the tundra.
