Build a Root Cellar on Your Farm
Try this time-tested method for storing your bounty of fruits and vegetables.
By Hank Will | Illustration by Ray E. Watkins, Jr.
WEB EXCLUSIVE: For information on root cellars and cellaring, see “Fundamentals of Root Cellaring” here. Also, check out Root Cellaring: Natural Cold Storage of Fruits & Vegetables, here.
You toil in the garden all summer and fall, and may even devour much of your bounty fresh off the plant. What, however, can you do with large harvests of crops such as apples, winter squash and potatoes? You can do as our ancestors did and store them in a root cellar.
Root cellars can be as rustic as small caves carved into limestone or as high-tech as a fully plumbed, wired and temperature-controlled room in your basement. In days gone by, root cellars took advantage of cool ground temperatures and strategic ventilation to keep the produce at just slightly over freezing through much of the winter and around 40 degrees below ambient during the heat of summer. A quick Google search will net you hundreds of ideas on how to create a storage cellar. Ours can be adapted to installation into a hillside or with an artificial mound in a flat area.
Site your cellar—a north-facing slope or otherwise shaded area where groundwater is at least 8 feet below the surface should suffice. A boom truck and hydraulic excavator, such as a backhoe on your tractor, should be able to access the site.
Size your cellar. How much produce do you anticipate storing? We suggest interior dimensions in the range of 5 feet wide, 10 feet long and 7 feet tall for starters.
Contact your local precast concrete company and spec out your cellar tank with them. These folks make culverts, septic tanks, storm shelters, etc. Be sure to have them cut two 4-inch-diameter holes (or another size to match your chosen vent piping) in the top to accommodate the vent pipes and, for an intake pipe, one about a foot off the bottom on the front wall. Arrange to have them cut one side of your tank to accommodate a standard metal door and frame. Most will want to cut the door opening after setting the tank.
Stake out your excavation and put your backhoe-equipped loader tractor to work. Excavate the hillside so the bottom of the cellar will drain with gravity. Or excavate the flat area to 3 to 4 feet to keep above the water table; at this depth you’ll only need to install a graded ramp or simple steps at the entrance (as opposed to going to the expense of installing a concrete stairwell and stairs). Be sure the excavations allow at least 2 feet of clearance all the way around the external dimensions of the concrete tank you ordered.
Spread, level and pack at least 6 inches of ¾–inch crushed stone on the bottom of the excavation.
Have the tank set in place. Be sure you specified that placing the tank was the precast company’s responsibility, unless you are able to handle it yourself.
Surround the tank with flexible, perforated plastic drain tile. Run it out to daylight in the hill installation, and trench it to daylight or a French drain in a flat excavation. Cover with pea rock to a depth of at least 6 inches more than the diameter of the tile. Optionally, cover the pea rock with a soil-excluding geotextile fabric to slow soil infiltration into the drain.
Backfill the tank sides in layers, compacting as you go. You may need to add retaining walls to keep material away from the door. In the flat installation you will need to mound soil against the side and back walls to build earth mass around the tank; place soil over roof after completing the next step.
Install your two vent pipes and intake pipe with blast gates to control the flow; waterproof the roof if you are concerned that it could leak; mound soil over it; and plant a soil-holding ground cover such as grass.
Install the metal door per the manufacturer’s instructions.
Build shelving. You can also store your home-canned goods in the root cellar. Cool, dark conditions will preserve them longer.
Monitor the internal temperature and do what you can to adjust it. If the cellar is too cold, you will want to partially close the blast gate on the intake and fully close one of the vent pipes. If it is too warm, you will want to reduce the flow of air through the cellar during the day but not shut it off, while opening it at night if it is cooler outside the cellar.
Spend some time monitoring how the temperature changes daily and seasonally, and take note of temperature gradients within the cellar to get a handle on where to place which fruits and vegetables to keep them in the best condition throughout the storage season.
Since most produce stores best at cool temperatures with relative humidity in the 90 to 95% range, you might occasionally wet the floor of your cellar, or use a layer of gravel or sand on the floor and keep it damp.