As I sit at my computer, I glance out the window at the droopy, frostbitten foliage of the purple nandina I like so much. The tender top growth took a hit during this month’s big freeze. So did the lamium and baby tears growing beneath the Japanese maple. What was once a soft, green carpet of ground cover is now a raggedy, blackened mat. Even in the greenhouse there’s trouble. My prized “Mrs. Quilter” and “Vancouver Centennial” geraniums are now compost fodder because I failed to turn on the heater in time.

But there was at least one victory against the dreaded cold. The voluptuous pink phormium in the container by the front door was carried into the garage before Jack Frost could snuff it. Last January I wasn’t so lucky, and lost a phormium in that same pot.

We gardeners could go on about what did and didn’t survive this January’s longer-than-usual freeze, but instead, let’s talk about what causes the problems.

Major damage occurs when water inside the plant freezes. The water in the space between cells freezes first, drawing water through the cell walls and causing them to shrink, which may kill the cells outright. When fluid inside the cells freezes, cell walls rupture.

If the freeze doesn’t get them, thawing often will. When the ice crystals in the intercellular spaces thaw suddenly, water rushes back into the cells, causing them to rupture and deflate. Phenolic compounds leak out of the cells, oxidize, and turn the damaged tissue black. When tender plants turn black and wilt as they thaw, you may as well kiss them goodbye.

Cold-resistant plants, such as our Northwest natives, have adapted to the climate by decreasing the water and increasing the dissolved solids (sugar, salts, protein) in their cellular fluid. This material is a natural antifreeze, lowering the point at which cell contents freeze.

Here are a few ways to protect our plants before the next cold spell hits:

One of the worst scenarios is when morning sun warms frozen plants quickly after a really cold night. You may be able to ward off damage by placing light insulating material such as bed sheets over the plants to allow them to thaw slowly.

Don’t wash frost or snow off with water. This, too, will thaw the cells rapidly and cause further injury. Snow provides plants with natural insulation.

Grass is a plant, too. Walk on frozen lawn as little and as lightly as possible, or you’ll damage it.

Don’t start pruning out dead wood now. Wait until new growth appears, when it’s easier to see the extent of damage. If you’re unsure whether or not a branch is alive, scrape off a little bit of bark. If there’s a greenish tinge to the cambium layer beneath the bark, it’s still growing. Dead wood is brown, black or slimy.

Plants that haven’t gone dormant, that are under stress or have poorly established roots are more likely to freeze. If you haven’t already done so, mulch beds with a couple of inches of organic mulch to help protect roots. Don’t put it directly against trunks of trees or shrubs, as bark-eating rodents may move in.

Newly-planted trees with south or west-facing trunks should be wrapped with light-colored bark wrap to help prevent bark from splitting on cold, sunny days.

Check plants growing under eaves to make sure they have enough moisture. Lack of soil moisture can worsen freeze damage to roots. Water well when temperatures rise above freezing.

Don’t fertilize until spring. No amount of fertilizer will bring a dead plant to life!

Move potted plants into a garage or other shelter during a heavy freeze. Container plants are more susceptible to damage because the soil freezes from all sides. Also, the ceramic and terra cotta pots they’re in can crack and split in freezing conditions.

Don’t use deicing salts near your plants. Most deicers are made from table salt (sodium chloride). Not only is it damaging to plants, but it harms soil structure, as well.

Salt splashed on deciduous plants may result in a dense growth of side branches nicknamed “witch’s broom.” Large quantities of salt will kill plants outright. Evergreen foliage will brown before it dies.

Damage from salt that has leached into the soil may not be noticeable until plants have leafed out. They may look scorched or stunted; growing tips may die back. If you think you have salt in your soil, as soon as the weather moderates, water deeply to leach the salt below the roots of plants.

There are alternatives to sodium chloride, but all have drawbacks. Potassium chloride is even more harmful to plants that sodium chloride. Calcium chloride is easier on plants, but it corrodes concrete. Urea won’t burn plants, but it’s a nitrogen and may cause over-fertilization. Calcium magnesium acetate (CNA) isn’t harmful to plants, nor is it corrosive. However, its price may burn a hole in your wallet!

The best alternatives for garden areas are either sand or clean clay cat litter. They won’t melt ice or snow, but they will provide traction and won’t harm your plants.

Ah, don’t you just love winter? It can be discouraging. But as I walk around the barren garden, I notice that crocuses are already pushing up below the birdbath. The pussy willows are fat and fuzzy, winter camellia, wallflower and hellebore are blooming. If you look closely, I know you’ll see the beginnings of spring in your garden, too.

Mariana Graham writes this column as part of her volunteer efforts as an Island County Master Gardener. E-mail her at frogardn@whidbey.net.