Humans may not like it, but snow is good for plants

Like hundreds of locals, shoveling the heavy snow last weekend was a nasty job. But for a gardener, the snow was welcome because it’s good for plants and other garden inhabitants.

We think of snow as an icy solid, but that’s not strictly true. Because each flake is unique, the tiny particles don’t stack tightly against one another on the ground. Instead, air pockets are formed, giving the accumulating snow a structure similar to the roll insulation used in buildings. Light, fluffy snowfalls can actually be made up of only 5% water crystals. The rest is trapped air.

Just as with building insulation, this air makes the transfer of heat between the atmosphere and the ground difficult. A foot of snow cover can make a 10-degree difference between the air temperature and the ground where the plants are.

Snow doesn’t provide much protection where it’s been crushed, so areas next to sidewalks and along driveways frequently have die-back because the packed snow damages the plants instead of protecting them.

We learned that lesson the hard way one year when we killed a young viburnum with the output of the snowblower. Now we make the effort to direct the snowblower stream away from the garden. We pile sidewalk snow on the parkway to protect the adjacent border, too.

Good snow cover also makes a physical barrier to protect plants, especially those with woody stems, from the desiccating effects of frigid winds and the glare of winter sun. It was easy to see this last winter when climbing roses exposed to arctic winds died back to the ground. And many local boxwoods only retained a skirt of green growth at the base where the branches had been protected by snow.

The release of winter moisture is also regulated by snow. Flooding is a problem when the soil is frozen and can’t absorb rainfall. Snow cover holds that moisture and then slowly releases it in spring when it can soak into the soil.

Toads and other creatures we rarely think about this time of year benefit from the protection of snow as well. A healthy population of toads feasting on slugs protects my hostas, so I can live with the fact that snow hides the local voles from predators. There’s a downside to everything and the benefits of snow outweigh the voles for me.

The forecast for this week is for sleet and rain. That will probably reduce our snow cover. As much as many people don’t want to hear it, winter rain and erratic temperatures are signs of climate change. When we moved here over 25 years ago, winter was winter and the snow stayed on the ground. Now Port’s winters are more like those we left 600 miles south in Kansas City. There, where winter temperatures bounce between 70 and -20, gardeners expect plants to take a beating.

Local gardeners should root for winter temperatures to stay in the 20s when snow is most likely to be fluffy and an excellent insulator. They should hope winter stays winter from first frost to last and that high winds don’t arrive with frigid air. That’s the kind of winter our plants are best suited to. Then they’ll thrive and fill our gardens with life when summer finally arrives.