By Jim McCausland, Sunset Magazine

When snow covers the garden, as it has recently in much of the country, it works both for and against the plants you’re growing.

It’s good insulation when it completely covers plants that might be burned out by frost—and in the coastal Northwest, where I live, we grow lots of plants whose hardiness is doubtful. The principle is that night-time temperatures are usually much lower when skies are clear than when they’re cloudy. So when the clouds blow away after the snow blankets your garden, temperatures usually drop. A friend in Vale, Colorado, had one garden thermometer covered by snow, and one above the snow level. She dug out the bottom one and compared: temperatures at plant level were 20° warmer than above the surface of the snow.

Use this by leaving snow on your compost pile (believe it or not, it holds in heat and keeps the pile working), on your winter vegetable beds (mine are pictured at bottom), and on beds that hold borderline perennials.

On the other side of the balance, snow—especially the wet snow that falls when temperatures are near freezing—tends to deform woody plants by weighing them down and either breaking or deforming them. The best strategy is to shake snow off or knock it off with a broom to keep it from building up. Branches of pyramidal arborvitae, for example, tend to pull away from the trunk and stay that way for months after a snow storm. Ugly.

Bamboos usually recover well from snowfall, but it varies a lot by variety.

Ned Jaquith at Bamboo Garden in Oregon says that the worst is Phyllostachys vivax, a timber bamboo (and the hardiest one at that) that tends to break off in snow or ice. Yellow-groove bamboo (P. aureosulcata) and its relations often break off at the crooks.

Black bamboo (P. nigra) goes down easily in snow or rain, but it recovers well too, as does Fargesia robusta (mine is pictured at right, before I shook if off). Golden bamboo (P. aurea) and moso bamboo (P. pubescens) stand up better in snow.

Ned says that the problem is that once bamboos are flattened by snow, they almost never grow back as straight as they were before snowfall—a good argument for shaking the snow off before it takes the bamboo down.