Outdoor Root Cellars

Enlarge Image Image Gallery You can harvest crisp veggies through snowy, wintry months using the plans in this article.  ILLUSTRATION: MIKE BIEGEL

You don’t need an underground room to have an effective root cellar — you can easily use soil, mulch and a few other tools to store vegetables and fruits without ever leaving your garden. Based on your winter weather and your available space, choose from these five ideas for outdoor root cellars to store your harvests through the snowy winter months.

The Organic Garden Blanket

The earth holds a surprising amount of summer heat in its mass. If you can trap this heat with some kind of fluffy organic blanket — leaves, clean straw, sawdust or even banked-up snow — it’s entirely possible to keep soil from freezing for months longer than if it were left bare. In areas with mild winters, you can even keep soil soft enough to dig in year-round, allowing you to harvest snapping-fresh, cold-tolerant vegetables while everyone else is relying on food from the grocery store. To make handling the blanket easy, tuck your leaves or other material into recycled trash bags before you lay them over your root crops.

Vegetables that can be harvested when the soil is covered in snow include beets, Brussels sprouts, cabbages, carrots, endive root, Jerusalem artichokes, kale, leeks, parsnips and salsify. After the first hard frosts mark the end of the growing season, nestle your crops under an organic blanket and they’ll keep reliably down to about 25 degrees Fahrenheit. They might even be OK at somewhat lower temperatures, depending on snow cover, the soil moisture level and the variety of vegetables involved. (You’ll know the weather has gotten too cold if the vegetables are soggy and soft when they defrost.)

The Trench Silo

Root crops come from the soil, and soil is wonderful at keeping them fresh. This is the power behind the trench silo, and a shovel is all you need to make one. Start by digging up your beets, carrots, parsnips and other long-keeping root crops, cutting the tops down to about 1 inch. Next, dig a trench 6 to 10 inches deep and 18 to 24 inches wide. Replant your vegetables close together in the bottom of this trench, replacing the soil around them and heaping it 6 to 10 inches above them, burying the crops completely with soil. A variety of crops can be kept in the same trench.

The temperature and humidity levels below ground are perfect for preservation, so you will be able to harvest crisp, living produce from your trench silo right through winter and into spring. Because your vegetables will be deeper underground after you replant them in a trench silo, they’ll be better protected against winter temperatures than if you simply covered them with an organic blanket. How low can the temperature get? That depends on snow cover (the more, the better — snow is a good insulator) and the type of soil you’re working with: Frost penetrates deeper into heavy, wet clay soil than it does into dry, sandy soil.