At a Glance: How to Build a Root Cellar
- Cost: The cheapest way to build a root cellar is to wall off a cold basement corner with framing lumber and foam board.
- Time: A basement room is a few weekends of work for most people (our estimate). An in-ground cellar can take a full season (also our estimate).
- Space: A 4 by 6 foot room suits most families, says University of Alaska Fairbanks Extension.
- Skill level: Basic framing for the basement room. Deep digging and a soil-covered roof belong to a pro.
It’s fall. The garden’s done, and the kitchen floor is lined with bushel baskets. You grew all of it.
Now you’re wondering where it all goes, because the fridge is full and you’d rather not can every last carrot.
That’s the job a root cellar does. It’s any space that stays between 32 and 40°F, stays damp, and moves a little fresh air. That’s all your carrots and potatoes need to keep for months.
And you don’t have to dig a hole in the yard. For most families, the easiest way to build a root cellar is to wall off a cold corner of the basement. It costs a fraction of an in-ground cellar, and it’s steps from your kitchen.
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What Does a Root Cellar Do for Your Homestead?
A root cellar keeps the food you grew good for months, with no power and no jars. It turns one big fall harvest into meals that last well into winter.
Here’s what that means on a real homestead.
You keep what you worked for. A basket of potatoes on a warm counter starts to sprout and go soft long before spring. In a cold, dark cellar, potatoes can keep about 8 months. Carrots packed in damp sand keep about 5.
That’s a whole season of weeding, watering and digging that doesn’t go to the compost pile.
You spend less time canning. Canning means a hot stove and long hours. A cellar needs neither. Carrots go into a tote of sand, potatoes go into a crate, and you carry up what you need for supper.
You still can and freeze the food that won’t keep fresh, like tomatoes and green beans. The cellar just takes a lot off that list.
You eat your own food in February. Say it’s a gray week in midwinter. You walk down the stairs with a bowl, dig a few carrots out of the sand, and grab a cabbage off the shelf. That’s dinner, and you grew it.
You’re picking up an old skill. Before every kitchen had a refrigerator, a lot of farm families kept their winter food in a root cellar. Maybe you remember a grandparent sending you down cool steps for a jar of beans or a few apples. This is that same idea, built to fit the house you have now.
And if your land is rock, sits on a high water table or has no hillside, you aren’t left out. A basement corner still works for most homes, and a small buried container works on ground that drains well. The next section helps you pick.
Which Root Cellar Should You Build?
Pick the path that fits your house and your harvest. A basement corner suits most families. Go in-ground only if you have a slope or a machine budget and you store root crops by the bushel.
| Type | Best for | Big plus | Watch out for |
|---|---|---|---|
| Basement corner room | Most families with a basement | Cheap, close to the kitchen | Basements run dry, so you add moisture |
| Hillside or in-ground cellar | A slope and a big harvest | Steady cold and damp from the soil | Needs a machine, shoring and a roof built to carry soil |
| Buried container in the garden | A first try with a small crop | Very low cost | Holds much less, and floods if water sits there |
What Helps on Day One
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Two things make the first winter go smoother. The first is a thermometer and hygrometer, so you know the room’s real numbers instead of guessing. The second is a sturdy lidded tote for packing carrots and beets in damp sand.
A lidded tote keeps the sand from drying out in a basement that runs on the dry side. It’s heavy once it’s full, so set it on the floor or a low shelf before you fill it. This 14-gallon one has a lid that snaps tight and grip handles.
- HEAVY-DUTY: Storage bin is a heavy-duty storage container used for storing and transporting items
- ERGONOMIC HANDLES: User-friendly grip handles decrease potential for back injury and finger strain
- HANDLE DRAINS: Holes in handle allow water to drain, reducing risk of bacteria build up
What You Need
Here’s the list for a basement corner room. Buy the lumber after your thermometer test, not before.
For a basement corner room:
- A thermometer and a hygrometer, or one gauge that reads both
- Framing lumber for two interior walls, plus wood rated for ground contact anywhere it touches concrete
- Rigid foam insulation for the interior walls and the ceiling
- A vapor barrier for the cellar side of the new walls
- Two vent pipes with screen or hardware cloth over both ends
- An insulated door that closes snug
- Slatted wooden shelves
- Shallow pans for water, or damp sand for packing root crops
How to Build a Root Cellar in a Basement Corner
This is the build most families can do with basic framing skills. Each step tells you why it matters, so you can adjust it to your house.
Step 1: Find the coldest corner
Look for a corner with two outside walls, as far from the furnace and water heater as you can get. Those outside walls pull cold from the ground and keep the room cool.
CHECKPOINT: Leave a thermometer in that corner for a week in late fall. If it trends toward 40°F or lower, you’ve found your spot. If it stays warm, try another corner before you buy lumber.
Step 2: Frame and insulate the inside walls
Frame the two walls that face the warm basement. Insulate those walls and the ceiling above, since the house is the heat you’re keeping out. Leave the below-ground part of the outside foundation walls bare. Bare masonry lets the ground’s cold come straight in, as University of Alaska Fairbanks Extension points out. Insulate any part of those walls that sits above the soil line.
Put a vapor barrier on the cellar side of the new walls. That keeps the damp air in the cellar from soaking into the rest of your house and rotting the framing.
STOP POINT: Any wood that touches concrete or soil must be rated for ground contact. Check that the treatment is safe for a room where food is stored before you buy it.
Step 3: Add two screened vents
Run one vent pipe in low to bring in fresh air and one out high to let stale, warm air leave. Cold air sinks and warm air rises, so this setup keeps air moving on its own. An existing basement window is often the easiest place to run them.
Cover both pipe ends with screen or hardware cloth. Mice love a warm pipe that leads to food.
Step 4: Hang a snug door
Use an insulated door, or add foam to a solid one. It needs to close tight so warm basement air doesn’t drift in every time the furnace runs.
Step 5: Build slatted shelves
Slatted wood shelves let air move around every crate. Keep them a few inches off the floor and away from the walls so damp spots don’t form behind the boxes.
Step 6: Set the moisture
Basements usually run dry, and dry air turns carrots limp. A dirt floor holds moisture on its own. On concrete, set out a few shallow pans of water, or pack root crops in damp sand in a lidded tote.
CHECKPOINT: Aim for 85 to 95 percent humidity on the hygrometer. A full cellar holds more moisture than an empty one, so expect the number to climb as you fill it.
Building Into the Ground or a Hillside
An in-ground cellar holds steadier cold and damp than any basement. It’s also a real construction job, and the hole is the dangerous part.
Before anyone digs
Before you build a root cellar in the ground, call 811 a few days ahead so buried utility lines get marked. Plan the hole on paper first, including where the dirt pile goes.
STOP POINT: Never stand in a hole 5 feet deep or deeper unless the walls are shored or sloped back. OSHA’s trench guidance requires a protective system at 5 feet, because the walls can collapse without warning. Keep the dirt pile at least 2 feet back from the edge.
Water, walls and roof
Water is the biggest threat to a buried cellar. Lay a gravel bed under the floor and give water a drain path away from the site. Pick a spot that doesn’t flood, and a shaded or north-facing slope if you have one.
Use block or poured walls, and wood rated for direct burial anywhere wood meets soil. Frost can reach more than 4 feet down in cold country, according to University of Alaska Fairbanks Extension, so carry insulation on any exposed walls below the frost line.
A roof covered in soil carries a lot of weight, and more after a heavy snow. Have a builder or engineer size that roof. Don’t guess at it.
Where Each Crop Goes
Not everything wants the same air. Most root crops want cold and damp. Onions and winter squash want it drier, and they’ll mold in a damp cellar. Here’s how to sort your harvest, using storage times from University of Alaska Fairbanks Extension and conditions from University of Minnesota Extension.
| Crop | Where it goes | About how long it keeps |
|---|---|---|
| Carrots | Cold and very damp, packed in damp sand | 5 months |
| Beets and turnips | Cold and very damp | 3 months |
| Cabbage | Cold and very damp | 4 months |
| Potatoes | Cold, damp and dark | 8 months |
| Onions | Cool and dry, with good airflow | 8 months |
| Winter squash and pumpkins | Warmer and dry, often a spare room shelf | 3 months |
Cure potatoes before they go in. University of Minnesota Extension says to hold them at 50 to 60°F for 14 days first. Onions cure at room temperature for 2 to 4 weeks.
Troubleshooting Your Root Cellar
Most problems show up in the first month, and each one has a simple fix. Find what you’re seeing below.
| What you see | Likely cause | Fix |
|---|---|---|
| Potatoes sprouting | Too warm | Move them lower and colder, and check the thermometer |
| Potatoes taste sweet | Too cold for frying potatoes | Keep frying potatoes at 40 to 50°F |
| Carrots go limp | Air too dry | Add water pans or pack them in damp sand |
| Mold on onions or squash | Too damp for them | Move them to a drier, warmer shelf or room |
| Water dripping from the ceiling | Moist air with nowhere to go | Open the high vent more |
| Chewed produce | Rodents | Screen every vent and seal gaps at the door |
Shortcuts to Avoid
Some time-savers cause the exact problems people blame on root cellars. Skip these.
- Insulating the below-ground outside walls. That blocks the ground’s cold, which is the whole point.
- Skipping the cure. Uncured potatoes and onions rot sooner.
- Closing the vents to hold cold. Stale air and trapped moisture bring mold.
- Hand-digging a deep pit with straight walls. That’s how cave-ins happen.
- Ordinary lumber against concrete or soil. It rots, and the shelf comes down.
When to Call a Pro
You can build a root cellar in a basement corner on your own. Bring in help for any digging or soil-covered roof, and for any work on your foundation.
- Any hole 5 feet deep or deeper needs a contractor with shoring, or a protective system an engineer designed.
- A roof that carries soil should be sized by a builder or engineer.
- Cutting a new vent through a foundation wall is a job for a mason or contractor.
- If your basement takes on water, fix the drainage before you build a cellar in it.
Buy Once
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You don’t need much. These last for years.
- Best: a digital thermometer and hygrometer with a min and max memory, so you see last night’s low.
- Better: a heavy lidded tote for root crops packed in damp sand.
- Budget: wooden crates or slatted boxes you already have.
Your First Winter of Cellar Food
The best time to build a root cellar is before the first hard frost, so start this week with a thermometer in your coldest basement corner. If it trends toward 40°F, you’ve got your cellar. Frame two walls, add two screened vents and a snug door, and set out a pan of water.
By the first hard frost, you can carry potatoes down in a crate. In February, you’ll pull carrots out of the sand for supper. That’s when the work pays you back.
Getting the house ready too? Work through our plan for winterizing your home, and stack the best firewood before the cold sets in.
FAQs
Is it worth it to build a root cellar if I already can and freeze?
Yes, for the crops that keep raw. Potatoes, carrots, cabbage, onions and winter squash store for months in the right air with no jars and no power. That frees your canning time for food that won’t keep fresh, like tomatoes and green beans. Most homesteads end up using both.
What temperature and humidity should a root cellar be?
Most root crops keep best between 32 and 40°F with 85 to 95 percent humidity. Onions and winter squash are the exception. They want it drier and a bit warmer, or they mold. A thermometer and a hygrometer tell you where each shelf really sits.
Can I build a root cellar in my basement?
Yes, and it’s the easiest place to start. Pick a corner with two outside walls, away from the furnace. Insulate the walls that face the house, leave the below-ground foundation bare, and add a vapor barrier on the cellar side. Basements run dry, so add water pans or damp sand.
Why do my stored potatoes taste sweet?
They got too cold. Cold storage turns some of the starch to sugar. University of Minnesota Extension says to keep potatoes for frying at 40 to 50°F to avoid that. Cure them at 50 to 60°F for 14 days before they go into storage.
Is it safe to dig a root cellar myself?
A shallow hole is fine with care. Once a hole reaches 5 feet, the walls can collapse without warning, and OSHA rules call for shoring or a protective system. Call 811 to mark buried lines first. Then hire a machine and a crew with shoring for anything that deep, and have a pro size a soil-covered roof.
Which Root Cellar Would You Build First?
If you build a root cellar this year, the choice comes down to space and budget. A basement corner is cheap and close to the kitchen, but basements run dry and warm. A dug-in cellar holds steady cold and damp, but it needs a machine and a careful build. A buried container costs almost nothing, but it holds a lot less.
Tell us what you’d store in it first.
