Beneficial animals Beneficial fungi Gardening Soil

What Happens to Soil in Winter? Does Everything Die?

The soil under your feet is still teeming with life, even in the frozen temperatures of winter. All photos: Soil Science Society of America

What follows is an article by Mary Tiedeman from the excellent site, Soils Matter, Get the Scoop! of the Soil Science Society of America, a go-to source for valuable and honest information on the soils we garden in.

Soil is essential to life. One reason is that soil protects plant roots, animals, and microbes from freezing in the winter. As air temperatures drop below 32 °F (0 °C), water within the top layers of the soil will eventually freeze. This is commonly known as the frost layer. So, while you think that once the ground is frozen, life stops in the soil, that’s very untrue. What’s going on under your feet is exciting stuff!

The frost layer can be several feet (1 meter or so) deep, though many factors influence how far down it goes. If a lot of snow falls on the ground early in the winter, it can serve as a blanket for the soil underneath. Organic matter plays a role in insulating soil, holding in heat stored below ground during the warmer months. The organic matter can be mulch or compost that gardeners add around the plants, or leaves that fall naturally. Dried leaves from plants also provide soil and root insulation. (To learn more about mulches and soils, visit the blog What Do Mulches Do.)

20181222B Soil Science Society of America jpg
Organic matter layer of dead and decomposing leaves, etc. (30 cm = 12 inches) above Alaskan “permafrost” provides insulation throughout the colder months, as well as nutrients for plant life during growing season. Photo: Mary Tiedeman

Perennial plants that grow in colder climates, such as many grasses, trees, and shrubs, are able to withstand freezing. They develop root systems below the frost layer. The root systems of these plants perform a number of tasks that protect them from the cold. Roots can release a lot of water from their cells into the surrounding soil. This allows roots to endure colder temperatures without the risk of internal water expanding and damaging root cells. Water within root cells also contains higher concentrations of sugars and salts. They both assist in lowering the freezing point of water inside and between the cells (much like antifreeze!)

Many soil-dwelling animals burrow below the frost layer to survive the winter months. These include insects, frogs, snakes, turtles, worms, and gophers. Some will hibernate. Others simply live on the food that they have collected for their long “vacation” deep underground.

What is even more fascinating? A great number of soil animals have evolved to withstand temperatures below freezing. At least five frog species in North America make their own natural antifreeze. This allows them to become completely frozen for long times without suffering any serious damage to the structures of their cells.

21081222C Soil Science Society of America.jpg
Soil microbes and creatures living in soil work year round on agricultural fields, even when snow covered.

Even soil microbes—bacteria and fungi that live in the soil year round—can be active in winter months. Studies in Antarctica show microbial life in permanently frozen ground (permafrost). In North America, once spring comes, the microbes become even more active. This ensures the biodiversity that is so important to keep plant and animal life healthy. (To read more about soil microbes, visit the blog Is It True Bacteria Live in the Soil. Isn’t That Bad?.)

Next time you are out braving the cold on a wintery day, try to imagine the root systems and living creatures below ground. We can thank soil for protecting and insulating its inhabitants. Whether they are hibernating or snacking on stored food, they are alive and well.

Larry Hodgson is one of Canada’s best-known garden communicators. After studies at the University of Toronto and Laval University where he obtained his B.A. in modern languages in 1978, he succeeded in combining his language skills with his passion for gardening in a novel career as a garden writer and lecturer. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He is a regular contributor to and horticultural consultant for Fleurs, Plantes, Jardins garden magazine and has written for many other garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening, Rebecca’s Garden and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 50 other titles in English and French. He can be seen in Quebec on French-language television and was notably a regular collaborator for 7 years on the TV shows Fleurs et Jardins and Salut Bonjour Weekend. He is the President of the Garden Writers Association Foundation and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. An avid proponent of garden tourism, he has lead garden tours throughout Canada and to the gardens of over 30 countries over the last 30 years. He presently resides in Quebec City, Quebec.

0 comments on “What Happens to Soil in Winter? Does Everything Die?

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: