Root Cellars and In-Ground Storage: Keeping the Harvest Without Power

By GoldBlock WorkshopPublished Updated

The short answer

University of Minnesota Extension gives storage conditions by crop: most roots, potatoes and cabbage want cold and moist (32 to 40°F, about 95% humidity); onions want cold and dry; pumpkins and winter squash want cool and dry (about 50 to 60°F). Onions and potatoes are cured first (UMN); UConn Extension says to keep fruit away from vegetables, check storage about weekly and discard anything rotten or moldy, and notes that carrots, parsnips and turnips “can remain in the garden, if rodents are not an issue.”

Key numbers

Match each crop to its conditions

University of Minnesota Extension gives these storage conditions by crop:

Conditions Crops
Cold and moist: 32 to 40°F, 95% relative humidity Potatoes, carrots, beets, parsnips, rutabagas, turnips, radishes, cabbage, Brussels sprouts, kohlrabi (UMN’s group also lists short-keeping crops such as asparagus, beans, broccoli, lettuce and peas)
Cold and dry: 32 to 40°F, 65% relative humidity Onions
Cool and dry: 50 to 60°F, 60% relative humidity Pumpkins and winter squash

UMN’s expected shelf-life figures: potatoes six months; onions four months; winter squash two to six months, depending on variety; radishes and Brussels sprouts one month; kohlrabi two months. Growing these crops is covered in Home Food Garden.

Curing produce for storage

Extension curing advice:

  • Onions: UMN: “Cure at room temperature for two to four weeks before storage.” Washington State University (EB1326, read October 14, 2026) advises 2 to 3 weeks spread out in a well-ventilated place out of sunlight.
  • Potatoes: UMN: “Cure at 50 to 60 degrees Fahrenheit for 14 days before storage”; Washington State University (read October 14, 2026): in darkness at 45 to 60°F for 10 to 14 days. NDSU Extension says to “store them in a cool, dark area with good air circulation and high humidity”; on greening, “Solanine has a bitter taste and can cause stomach symptoms such as vomiting and diarrhea if you eat enough of it,” “Removing the green portions by simply cutting them out will eliminate most of the toxin,” “if more extensive greening occurs, throw the tuber away,” and “Never eat tubers that are green beneath the skin.”
  • Winter squash and pumpkins: advice differs. Washington State University (read October 14, 2026) cures them for 10 days at 80 to 85°F; UMN: “Curing is unnecessary. Do not cure the Table Queen variety.” WSU excludes acorn squash from curing.

Root cellars and other cold spaces

University of Connecticut Extension (Diane Wright Hirsch, 2017) advises keeping an indoor storage space “cool enough (32˚F–60˚F)” with little temperature fluctuation, checking for gaps around vents or windows that could admit rodents, and:

  • Keep fruit away from vegetables: “fruits release ethylene which speeds the ripening process of vegetables.”
  • Check about once a week and “remove and discard anything that is rotten or moldy.”
  • Use food-grade containers that animals cannot chew through. “Never use drums, garbage cans or containers that might have held garbage, pesticides or other chemicals.”
  • Clean all produce with water and a brush before eating.

UConn notes a well-ventilated basement with central heating is “generally dry” at 50˚F to 60˚F, suitable for short-term storage of potatoes, onions and squash. University of Alaska Fairbanks Extension (HGA-00331, revised June 2020): “Thermometers can be positioned throughout the cellar to monitor temperatures.”

Leaving crops in the ground

Carrots, parsnips and turnips “can remain in the garden, if rodents are not an issue” (UConn). UConn: “Once the ground is cold, or begins to freeze, protect the vegetables from frost and fluctuating temperatures” “with insulating materials such as clean straw, hay, dry leaves, corn stalks, or wood shavings, and some soil”; “A well-drained location is essential”; “Be sure that the insulating materials used are not contaminated with pesticides or manure.”

Mounds and pits: once a mound or pit is opened, UConn says all produce should be removed; it keeps only about one to two weeks afterward.

Common questions

What temperature should a root cellar be?

For most roots, potatoes and cabbage, 32 to 40°F with high humidity (about 95%), per University of Minnesota Extension. Onions want the same cold but dry air; squash and pumpkins want 50 to 60°F and dry.

Can I store apples with potatoes?

UConn Extension: “fruits release ethylene which speeds the ripening process of vegetables.”

How long will potatoes keep?

UMN: “The expected shelf-life is six months,” in cold, moist storage, after curing at 50 to 60°F for 14 days.

Can I leave carrots in the ground over winter?

UConn Extension describes leaving them in place where rodents are not a problem: cover them with straw, hay or dry leaves plus soil once the ground cools, on a well-drained site, and dig as needed (UConn Extension).

Do I need to cure winter squash?

Extension advice differs: Washington State University cures squash at 80 to 85°F for 10 days (read October 14, 2026), while UMN says “Curing is unnecessary.” WSU excludes acorn squash and UMN says “Do not cure the Table Queen variety.”

Where to go next

Sources