portland nursery

Brrrrr! Cold winds and a chance of snow!

Here are a few things you can do to protect your garden in winter weather.

Winter berries

Don't forget to water!

Moist roots are much more durable in cold weather than dry roots! It is easier to take care of your plants before insulating or draining pipes.

Often our coldest weather around here comes with dry air and clear skies, sometimes with high winds. Make sure the soil around your plants is moist during these times. Moist soil is a better insulator than dry soil. Even if the water in the soil freezes, it is still better off moist.

Winter Vegetables

Kale, chard, onions, garlic and shallots are fine if left uncovered. Lettuce and other greens, broccoli, cabbages should be harvested or protected with row covers, frost blankets or cold frames.

Prepare for heavy snow or ice

Heavy snow or ice can cause branches on some conifers like Arborvitae and Junipers to bend down under the weight, or to splay. To avoid this problem, tie twine in a spiral shape, like a candy cane, around the length of the tree before snows arrive. This will support branches during damaging weather. Twine should be removed in spring when danger of harsh weather passes.

Prepare evergreens for winter winds

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.

Winter berries
Winter berries

Bring tender plants indoors

Plants that are in pots and are considered to be tender should be be checked for hitchhiking insects and brought into a cool room of the house, like a garage, for the duration of the most extreme temperatures. Citrus, Cactus, Gardenias, Bougainvillea and tropical Jasmines are all in this category.

Move containers up close 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 pots. Many products can be used for insulation. Portland Nursery sells frost blankets and burlap for wrapping containers. Using old sheets or blankets will work fine too, but avoid using plastic to cover plants since moisture and air circulation is important. Adding straw or leaves under frost blankets will increase protection.

Plants in the Ground!

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. Hebes, New Zealand Flax (Phormium), Camellias, 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.

We stock frost blankets in 5x50’, 5x25’ as well as 12’ wide in bulk to help protect plants during severe weather conditions. It is permeable and reusable.

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, and some prefer late winter (and for some, either is fine). If you have particular questions about your plant type feel free to contact us.

Winter berries
Winter berries

Adding Mulch

Before the cold weather settles in, lay mulch in the garden, if you haven’t already. 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 something like a blanket to trap some of the heat in the soil, keeping the soil temperature above freezing even when the air temperatures are temporarily below it.

Please note that 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. Keep in mind that 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.