Appalachia--Science in the Public Interest

ROOT CELLARS

Root cellars have long been used to store food in order to increase the diversity of flavors on the winter table. Root cellars allow roots and other crops to be preserved through cooler weather in cool, dark, and moderately humid storage space. We give this a special place because it is both a good way to preserve food and is a storage area as well.

Contents. Produce which can be stored in a root cellar includes: beets, carrots, garlic, Hamburg rooted Parsley, horseradish, Japanese radishes, Jerusalem artichokes, onions, parsnips, potatoes, rutabaga, salsify, sweet potatoes, and turnips -- all of which can be stored under moderate conditions. Cabbage, celery, pumpkins, winter squash, pears, apples, and endive can be given longer term storage, while cauliflower, cantaloupe, cucumbers, eggplants, sweet peppers, ripe tomatoes, and watermelon only a short term (up to a month).

Maintenance. Maintaining the root cellar at 32 to 40F makes for an ideal natural refrigerator. This temperature can be maintained in winter with proper venting and insulation. In spring and fall, allow cool night air to flow in, and close off the cellar during warmer parts of the day. Place the produce at different temperature gradient levels within the cellar itself. Note that pumpkins, sweet potatoes, and winter squash need warmer temperatures in the 50 to 60F range, and peas, beans, garlic, and onions need dryer conditions (60 to 70% humidity) then those found in root cellars (85 to 95% humidity).

Construction. Root cellars range from dirt and rock compartments, which are partially or totally underground, to above-ground structures with rooms that have earth mounded around them for insulation. The goal is to satisfy three conditions: coolness, darkness, and proper humidity. "Cool" does not mean frigid. Darkness is essential to keep roots from sprouting. Wooden slats or flooring should not be used in a root cellar. If possible, the cellar should have an earth floor covered with gravel. Stone or cement walls work quite well and can even stabilize moisture content. The space does not have to be air tight, but the tighter it is, the easier it is to control temperature and air quality using vents. (See Matlack in reference).

Earth Sheltered Cellars. For excavated root cellars, native materials such as stone, or earthen walls should be used. Several advantages accrue from building an excavated structure and berming in all sides with earth. The berming insulates, and keeps the cellar dark, cool, and at a constant level of humidity. Drainage is important to keep the walls from expanding and contracting due to freezing and thawing of water laden soil. After backfilling the soil around the walls to about two feet below the surface, lay a perforated drainpipe around the back of the cellar, extending all the way around the sides at a slope to daylight. This pipe should be placed in a bed of gravel and the top covered with plastic or other waterproof material.

If possible, dug-in cellars should have poured concrete roofs reinforced with rebar. Once the concrete has set (3-7 days) the exterior of the roof should be covered with rigid styrofoam insulation and a layer of plastic (6-mil polyethylene). A layer of dirt should then be added and grass planted to prevent erosion.

Some good tips in construction include not building beyond your needs, laying drain pipe to divert outside moisture away from the storage area, reinforcing the ceiling to avoid weight problems, and insulating exterior concrete walls and roof with rigid styrofoam or urethane and covering with a sheet of 6 mil polyethylene plastic sheeting. In colder climates an ante-room or airlock may be required. Air flow around the vegetables prevents produce from becoming moldy. For the best humidity control use a hygrometer (humidity measuring device) along with adjustment of outside vents.

For free-standing root cellars, use native materials such as stone, earthen walls, or concrete block. Several advantages accrue from building a free-standing structure and berming in all sides with earth, though strictly speaking this is more of a bunker than a cellar. Nonetheless, the berming insulates, and keeps the cellar dark, cool, and with relatively stabile humidity.

Produce Preparation. Cut away greenery and rotting areas from fruits and vegetables to be stored in the root cellar. Remove excess soil from roots and arrange them so that air can freely move through the storage area. Store produce making optimal use of the temperature gradient. Choose packing materials best suited for the particular vegetable. Use up short-term vegetables early, and check regularly during extreme cold periods to ensure vegetables do not freeze.

REFERENCES Bubel, Mike and Nancy. "The Year-Round Harvest: The Fundamentals of Root Cellaring," Mother Earth News. August/September, 1991, pp. 74-82. Matlack, Fred. "Build a Root Cellar!," Organic Gardening. November, 1992, pp. 34-35.