How to Build a Root Cellar in Your Basement

No place for a traditional root cellar? Build a cold-storage area in your basement to enjoy fresh root vegetables all winter long.

by Amy Grisak
PHOTO: iStock/Thinkstock

While many of us dream of having the ideal root cellar where we can venture into its chilly depths and gather fresh fruits and vegetables held over from the summer season, the reality is that it isn’t a possibility for most of us. But even if you don’t have the means or the space to build a model of perfect cold storage, the good news is you can create a highly functional system right in your home.

What You Need

The magical combination of temperature and humidity proper root-cellar storage requires depends on the particular type of fruit or vegetable you wish to keep in long-term storage. For example, root crops, such as potatoes and carrots, do exceedingly well when kept in an area roughly 32 degrees F with a 90- to 95-percent humidity level. At these conditions, you can feasibly keep them until the following late spring or early summer. Squashes, including pumpkins, with their durable outer skins, need a slightly warmer temperature ranging between 50 to 55 degrees F and relatively dry conditions at 50- to 60-percent humidity. Given this environment, you can enjoy them well into the winter and sometimes into the spring. Once you know what produce you want to store, you can determine how to go about creating an environment where they’ll keep well.

Identifying Your Storage Area

root cellar basement

Begin by looking at the setup of your basement to determine the best location to create a small cold-storage room or storage area. You’ll want a place that’s cool and properly ventilated. Be mindful to keep away from heat sources, such as the furnace or hot-water tank. Having a wood-burning or pellet stove in the basement can present a few challenges, though it doesn’t preclude you from successfully storing fruits and vegetables for the long term.

Ventilation is important because it allows fresh air to enter the room, as well as letting ethylene, a naturally occurring gas expired by the fruits and vegetables during the ripening process, to escape. Without proper ventilation, your produce will break down at a faster rate. If you’re able to locate an area with a window, this is ideal. The window can be covered to block out light and opened on occasion for passive ventilation. You can also install a PVC ventilation pipe through the window opening to allow for consistent passive ventilation, or use a small fan (like you would in a greenhouse) attached to the PVC pipe to pull gasses out of the cold storage. If the best storage area in your basement isn’t near a window, the other option is to drill a hole through the wall and insert a ventilation tube.

Building the Cold-Storage Room

Once you’ve determined your location and ventilation options, your next considerations are the walls and insulation. Concrete blocks with rigid foam insulation can create a snug storage space, though you might find it easier to build the walls out of 2×4 lumber with 3½-inch fiberglass insulation sandwiched in between. Use faced insulation—the kind with the foil paper on one side—if possible; otherwise, add plastic sheeting as a vapor barrier. It’s not necessary to put insulation on the exterior wall (aka the basement wall), but you will want to put it on the ceiling and along the walls dividing the room from the rest of the basement.

Regulating your temperature and humidity can be as easy as opening a window or the vent. Many people take advantage of the cool fall nights to allow cold air to pour into the room, ultimately bringing down the temperature to the desired range. Humidity, which is a challenge in drier regions of the country, can be bolstered by setting a pan of water in the room.

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The ideal temperature and humidity you want to maintain depends on what you want to store. If you’re storing several items, consider what you have the largest amounts of and make that your baseline gauge. Below is a chart of commonly stored fruits and vegetables, their ideal storage conditions, and how long they keep. Use this as a reference point when making your decisions.

winter vegetable storage root cellar basement

Containing Your Produce

Build shelves to hold burlap bags of produce, or create bins to keep everything in place. Here are some additional tips to keep in mind when working with specific produce:

  • Potatoes do best when placed in burlap bags, in order to prevent light from reaching them and turning the skin green, and either stacked in bins or set upon shelves.
  • Onions can also be stored in bags, but because they require more air circulation, avoid stacking them upon one another.
  • Sweet peppers will often keep very well in cold storage. Place them in a single row in a shallow box or container and cover with a plastic bag to retain humidity. Check them frequently, and use them before they show spots or softening. They will often keep for two to three weeks or longer.
  • Tomatoes, particularly green ones, can also hold up well in a similar storage system for months. Place them in a single row in boxes and cover with a plastic bag or towel. Use them as they ripen, and if many of them are already mature, simply be vigilant to use them before they rot.
  • Squashes will store well in a similar environment to tomatoes, where the temperature is closer to 50 or 60 degrees F. Simply set them on shelves and check them periodically to use any that show signs of degradation.

Other Storage Options

If you don’t have the means to build a separate cold-storage room in your basement, don’t feel that you can’t store produce throughout the winter. Many people make the best of what they have with perfectly acceptable results. As you’re looking for a place to keep fruits and vegetables, keep your mind focused on staying as close to the standard storage requirements (listed above) as possible. It doesn’t have to be perfect, but the closer you can get, the better the outcome will be.

Lauren Dixon of Creston, Mont., hopes to build a root cellar someday, but for the time being, she’s had impressive success simply segregating a bedroom in her 900-square-foot log cabin for produce storage.

“I turn that into a cold room,” she says. “I let it stay just above freezing.”

The interior walls of Dixon’s home are very well insulated, allowing her to open the window in the bedroom to cool it down after insulating the door with wool blankets. The room stays cold without kicking her furnace into overdrive. She uses easily stackable dairy crates as storage bins for potatoes and other root crops because they provide ample ventilation, and shelves are available to keep other foods organized.

“It works really well,” Dixon says. “Usually things start to turn on me around April, which is not that bad. I’ve had seed potatoes make it all through to spring planting.”

If a separate unheated room isn’t available, some people store produce in the space underneath a staircase because it’s usually dark and out of the way.

Although many of us love the idea of having an in-ground root cellar where we can keep the season’s bounty well into the winter months, knowing that we can successfully store many of these same fruits and vegetables down the basement stairs offers equal satisfaction.

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