Root Cellars 101- Root Cellar Design, Use and Mistakes to Avoid

In this article we’ll talk about 5 things you must include in a root cellar design, plus 10 tips for fruit and vegetable storage. There’s also a printable storage guide for over 30 fruits and veggies, and jump links to additional information at the bottom of the post.

A root cellar is a great low-cost way to store food – not just root vegetables, but other fresh produce, too. They require no energy to use and very little maintenance. You can build in a root cellar when your home is under construction, but it’s also possible to add a root cellar to your basement, or build one outside your home.

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What is a root cellar?

Dig a deep enough hole, and you’ll find that the ground is cool (and often moist). Root cellars tap into those cool, moist soil conditions and use them to store produce – like your refrigerator produce bin.

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Building a Root Cellar

There are five major elements that a root cellar requires:

  1. Ventilation:  Some produce gives off ethylene gas, which can cause other produce to spoil. Also, a tightly sealed cellar will increase the risk of mold. Make sure fresh air can get in, stale air can get out, and air can circulate around the produce.
  2. Earth-shelter:  The soil insulates and maintains a cool temperature. A packed earth floor or gravel floor is better than concrete for keeping moisture levels high.
  3. Darkness:  Light can trigger sprouting, so if you have a window in your root cellar, keep it covered, and don’t leave the lights on.
  4. Humidity:  A high humidity level of 85-95% keeps produce from drying out. Note: Humidity that is high enough for produce may cause canning jar lids to rust, so be sure to check lids and rotate stock if you store canned goods in the root cellar.
  5. Shelving/Storage bins: Wood shelving and bins are naturally antibacterial. Wood also conducts heat more slowly than metal, and doesn’t rust. Avoid treated wood, and stick to those that are naturally rot resistant.

Types of Root Cellars and Natural Cold Storage Options

Natural cold storage options include (click on any item in the list to jump to more information below):

  • Basement or Under Porch Root Cellar (accessible from inside the home)
  • Traditional Root Cellar (buried below ground, accessible from outside)
  • Earth Berm (at ground level or partially above ground)
  • Barrel in the ground

These earth sheltered fruit and vegetable options work best for those in cooler climates, where the ground temp is naturally cooler. For those in warmer areas, check out the posts Above Ground Root Cellars and Build Your Own Walk In Cooler with a CoolBot Controller and A/C Unit.

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You may not be able to store things like we northerners can, but the Above Ground Root Cellar post will give you some ideas of what you can store, plus tips for year round food production so you always have fresh, local food to enjoy. The Coolbot makes it very affordable to use a standard AC unit for refrigerated fruit and vegetable storage.

10 Tips for Fruit and Vegetable Storage in a Root Cellar

Key storage tips to remember:

  1. Late-maturing crops store better than early maturing crops. Specific varieties also store better than others. Watch for varieties that are noted for good storage quality.
  2. Check fruit and vegetable condition at storage time. If you note any damage on produce, use those items first. One bad apple or onion can spoil the whole bin, so it’s good to regularly inspect produce during storage, too.
  3. Cure the vegetables that need it before storage. Vegetables that require curing include onions, garlic, winter squash (pumpkins) and potatoes.
  4. Most root vegetables store best in the root cellar if they are wiped off rather than washed. Wipe excess dirt off of carrots, beets, rutabagas and turnips and store them in lightly dampened leaves or straw. Use fresh leaves each year to prevent potential pathogen buildup. Sand and sawdust will also work, but are messier.
  5. If you have a muddy garden at harvest time, it’s okay to wash, but make sure dry up excess moisture (and cure if needed) before storage to avoid rot.
  6. Less-than-ideal conditions shorten storage life – try to get as close as possible to target temps and moisture levels. Use different areas of your storage for crops that are a best fit, such as storing carrots and beets lower (colder) and tomatoes and winter squash higher (warmer). (See chart below.)
  7. Store fruits that give off ethylene gas away from produce that can be spoiled easily by ethylene gas. You can also wrap fruit that produces excess ethylene in newspaper to contain the gas. See Ethylene Gas below for more information.
  8. The odor of strong smelling vegetables, like turnips and cabbage, can be absorbed by fruits and other vegetables. Store them away from other food and where the odor cannot waft into the house.
  9. Do not allow fruits and vegetables to freeze. They will get mushy and rot. 
  10. Track temperature and humidity to measure your root cellar performance. The SensePushunit can track up to 20 days and sync with your smartphone.

Fruit and Vegetable Storage Chart

The chart below gives preferred temperature and moisture ranges for root cellar storage of a variety of fruits and vegetables. Adapted from the University of Missouri Extension Office. 

root cellar storage chart

Root Cellar Location – In the Basement or Buried Outside?

By default, the word “cellar” means “underground”. A big part of why root cellars work as well as they do is that the earth remains at a relatively constant (cool) temperature. This temperature will vary, depending on your location. Closer to the equator, and it may be cooler than air temp, but still isn’t likely to act well as a root cellar. At the opposite extreme, you have arctic permafrost, which the native folks use to store whole animals.

Retrofitting a Root Cellar in an Existing Home

The easiest option for building a root cellar is to section off a part of the basement (or maybe even the whole basement, if you live in an old farmhouse) for produce storage. Old dirt floor basements without heat are great for maintaining proper temperature and humidity levels.

Select an area with an existing window if possible, and use the window for ventilation. Fill the window with exterior grade plywood, and cut the necessary vent holes through the plywood. (The plywood also helps block light.)

North facing corners work well, because you can leave the two exterior walls uninsulated, and only insulate the interior walls. A north facing wall won’t gain heat from the sun. Use materials that tolerate moisture exposure.

Your basement root cellar should have no standard heating or cooling. Take note of ductwork or piping that runs through the ceiling above your root cellar (if any), and make sure vents or hot water pipes are well insulated so they don’t bleed heat into your root cellar.

For additional food storage space, build shelving on the outside of your basement root cellar for canned goods or other items.

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Adding a Root Cellar in a New Home

Many new homes have small concrete exterior porch. Typically this area has 4ft footings and is filled under the porch with dirt. You need to put a foundation wall under it anyway, so why not put this area to good use?

To turn this under porch area into a root cellar, have the builder put in full footings, an insulated exterior grade access door from the basement and two 4 inch vent holes. Add concrete slab on top as normal. This area could also be a wine cellar or safe room.

Our under porch root cellar measures about 6’x8′, which provides plenty of room for our stash of root veggies, plus gives a nice sized porch above. Locating the root cellar outside the footprint of the home allows the root cellar to maintain cooler temperatures more easily than a cellar located within the house.

"root cellars 101" test over table piled carrots and beets

Building a Root Cellar Outside the Home

For an exterior root cellar, similar rules apply – have good ventilation, keep it earth sheltered and dark. A north facing door is preferred, to avoid sun beating in and heating your cellar up. Aim for at least one to two feet of soil covering the root cellar, and make sure you choose a premade option (some people have used new septic tanks) or materials that are rot resistant and can stand the weight of wet soil.

Traditional Root Cellar

This is what most of us think of when we hear the phrase “root cellar”. There are insulated doors that lead down into the earth. It’s dug down or into the side of a hill. Walls are concrete, cinder block, or more creative materials like old tires. You need to make sure the roof and walls are well supported to avoid collapse. Engage an engineer to help ensure safety.

Earth Berm Root Cellar

Above ground root cellars are usually partly sunken with earth mounded on 3 sides and the door avoiding the direct sun. See the  Above Ground Root Cellars post for more information.

For a great resource on building a homestead root cellar, check out the book below by my friend, Teri, of Homestead Honey.

Barrel in the ground A (approximately Zones 6-9)

The size and depth depends on the zone you live in. A simple bucket, with holes drilled in the bottom and top, buried level with the soil with a bale of hay as an insulating cover will work into zone 7 and possibly into zone 6 depending on cover and conditions. The colder and hotter zones require the bucket or barrel to be deeper, and more insulation on the top to avoid the freezing surface temps.

Barrel in the ground B (approximately Zones 3-6)

Buy one large heavy duty garbage can, and a smaller garbage can that fits inside the larger one (with an inch or two gap). Both the larger garbage can and the smaller one need holes in the bottom. The inside one needs a cover with vents / screen. Cover exterior holes with screens to keep rodents out. It also needs significant insulation above it.

Prepare a hole that is deeper than the large garbage can, with rocks and gravel in the bottom to create a simple French drain. If water drains well, you will need a small amount of rocks and gravel. If soil doesn’t drain well, you need to go deeper and wider so your underground storage barrel doesn’t turn into a water hole. Another trick is to dig a very deep, large hole next to the garbage can hole and fill that hole with rocks. The deeper hole acts as a drain for your shallower garbage can root cellar.

Once you have the large garbage can in the ground and secure, lower the smaller one into the larger barrel. Store food in the small barrel. When you need access, grab from the top or pull out the smaller barrel. This makes it easier to reach food the bottom. There are many variations on this. Search “garbage can root cellar” for examples.

stored potatoes

Root Cellar Ventilation

Improper ventilation is one of most common mistakes that people make when designing/installing a root cellar. They build their underground food storage airtight to keep things nice and cold, and everything spoils. Why? Because some foods give off ethylene gas, which speeds ripening (and rotting). A root cellar that is too airtight may also build up excess humidity, leading to mold and mildew.

How should you ventilate your root cellar? Use two vents, about 3-4 inches in diameter. Place the vents so that one is near the top of the root cellar to exhaust stale air and ethylene gas. The other vent should be run down to near the floor, to drop in fresh air. 4 inch vents should be adequate for to up to around an 8’x10’ room. If your cellar is larger than this, consider additional ventilation. Make sure to put screen on the outside to keep mice and other small animals out!

Ethylene Gas

As fruits such as apples and pears ripen, they give off ethylene gas, which decreases the storage life of some produce. Ethylene gas can cause sprouting, decay, mold, yellowing, shrinking, toughness, softness, bitterness and other damage.

To combat spoilage from ethylene gas, segregate fruits and veggies that produce excess ethylene gas from those that are easily damaged from ethylene gas. (This is a good idea for your refrigerator produce bins, too.)

Fruits and Vegetables that may create excess ethylene gas include:

Apples, apricots, avocados, ripening bananas, blueberries, cantaloupe, citrus fruit (not grapefruit), cranberries, figs, guavas, grapes, green onions, honeydew, ripe kiwi fruit, mangoes, melons, mushrooms, nectarines, okra, papayas, passion fruit, peaches, pears, peppers, persimmons, pineapple, plantains, plums, prunes, quinces, tomatoes and watermelon.

Fruits and vegetables that may be damaged by excess ethylene gas include:

Asparagus, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, chard, cucumbers, cut flowers, eggplant, endive, escarole, florist greens, green beans, kale, kiwi fruit, leafy greens, lettuce, parsley, peas, peppers, potatoes, potted plants, romaine lettuce spinach, squash, sweet potatoes, watercress and yams.

Root Cellar Lighting

Light exposure is the enemy of food storage. Every time I see people lining up their canning jars or spices on open shelves, I cringe. It looks beautiful, but light bleaches out the color and the nutrient value of foods.

In the root cellar, light exposure may lead to sprouting and green potatoes. If you’re venting through a window, cover the rest of the window. If you have a light in your root cellar so you can see your food storage better, don’t leave the light on when you’re not using it. A hunk of burlap drawn over bins of potatoes or fruit will allow ventilation while still blocking the light. A single incandescent light (switched on exterior) should provide adequate lighting (unless your room is really huge) and, if for some reason your storage gets too cold, you can always use it to introduce a little heat.

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Root Cellar Humidity – Keep Things Moist But Not Wet

Checking the fruit and vegetable storage chart, you’ll see that most store best with fairly high humidity. If you have a dirt or gravel floor in your root cellar, you’re in luck, because the natural ground moisture will help keep your produce damp.

Produce will give off some moisture on its own, but if you note that your produce is shriveling, your root cellar is probably too dry. Take a tip from the grocery stores, and try a little misting action with a spray bottle. Avoid getting any area too wet, as that can lead to standing water and potential mold growth. Some people leave trays of water in the root cellar to increase humidity. Be careful with this option, as it can also result in bacteria or mold growth.

pumpkins and squash

Root Cellar Shelving

Shelving should allow airflow and add storage. Keep a gap between the shelving or storage bins and wall to encourage air flow. Remember to check the chart and keep produce that likes cooler temps lower and food that like warmer temps higher.

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