Building a Root Cellar

What does a root cellar actually do?

A root cellar uses the steady temperature of the ground to hold crops at cool, humid conditions that slow spoilage. It works best for sturdy storage crops such as root vegetables, cabbages, winter squash and apples, each of which wants somewhat different conditions. Look to extension publications for the storage conditions of each crop.

A root cellar does not replace safe food preservation methods for foods that need canning, freezing or drying. For those, use current tested recipes from the National Center for Home Food Preservation, the USDA Complete Guide to Home Canning or your extension office, and never rely on untested or old recipes.

Think of the cellar as one part of a storage plan. Crops grown, harvested and handled well keep much longer than those that were bruised or picked at the wrong stage. Ask your extension office for crop-by-crop advice on curing and storing, since each crop differs.

What are my options?

Choices include an unused basement corner, a basement room with an outside vent, an insulated room, a buried container or a hillside cellar. A basement room is usually the easiest and cheapest category of project, because the structure already exists.

Freestanding underground cellars need excavation and a strong structure. Soil can collapse, so deep or large digging should be handled by a qualified contractor, not improvised. Ask your local building office what rules and permits apply.

What site conditions matter most?

Drainage is first. A cellar in ground that floods or holds water will mold and may be unsafe. Choose a slope or high point, and check the water table with your county office or a soil survey. The Web Soil Survey from the Natural Resources Conservation Service can show soil drainage classes for your parcel.

Stay well away from wells, septic systems and buried lines. Call your utility locating service before any digging, and ask your health department about required distances from wells and septic systems.

• Good drainage and a low water table
• Distance from wells and septic components
• Utilities located and marked before digging
• Stable soil, with professional advice on bracing

How do I handle ventilation and humidity?

Air movement removes ethylene from ripening fruit and keeps conditions steady. A common design uses two vents, one low for cool air to enter and one high for warm air to exit, with ways to close them in extreme weather. Humidity should stay high enough to keep produce from shriveling but not so high that mold grows.

A thermometer and hygrometer let you track conditions. Adjust vents as the seasons change, and ask your extension office for target ranges for the crops you grow.

How do I keep it safe?

Enclosed underground spaces can have poor air, and a dug cellar can collapse. Never enter a newly dug or damp enclosed space without ventilation and a second person nearby. Use a sturdy structure designed or approved by a qualified professional, and make sure there is a safe way out.

Any electrical lighting should be installed by a licensed electrician where required, and moisture-rated. Keep the entry clear and prevent children from playing in or around it.

Before you commit to a new build, test a spot you already have. Place a thermometer and a hygrometer in a basement corner, an unheated room or a cool crawl space through a season. The readings will show whether a simple solution is enough.

What should I store and how do I keep it from spoiling?

Store only sound produce. Bruised or damaged items spoil sooner and can affect the rest. Keep different crops separate where they have different needs, and check the cellar every week or two to remove anything that is rotting.

Clean shelves and bins each year. Rodents are a common problem, so seal gaps and use metal or hard containers for food. If food smells off, looks slimy or has mold, do not eat it, and ask your extension office if you are unsure about a specific item.

What does it cost and is it worth it?

Cost categories include excavation or materials, concrete or blocks, insulation, vents, shelving, drainage, lighting and any professional design or inspection. Costs rise quickly for underground construction, so compare with simply insulating a basement corner.

Match the project to how much you grow. Someone storing a few bushels may do very well with a simple basement room.

Think also about resale and insurance. A below-grade structure can affect how your property is assessed and covered, so ask your insurance agent and local building office before you begin, and keep any plans and permits in a safe place.

Last reviewed: November 12, 2026. Written by the Homestead & Small Farm Editorial Team. See our editorial policy.