Heritage Field Notes · Category G
Before refrigeration, every household in a cold climate kept vegetables through winter. The USDA documented exactly how they did it. Most of the techniques are still viable — and several require nothing more than a refrigerator.
In 1942, the USDA Bureau of Plant Industry published Farmers' Bulletin No. 1939, Storing Vegetables and Fruits in Basements, Cellars, Outbuildings, and Pits. The bulletin's opening sentence made the objective explicit: "The proper storing of vegetables and fruits produced in the home garden or obtained cheaply in season conserves labor, money, and food."
The context was wartime. Food rationing had begun. Commercial refrigeration was difficult to obtain. Extension services were encouraging every household with a garden to extend their harvest through winter using the same techniques rural households had practiced for generations. The bulletin was an attempt to systematize that knowledge — to translate what farm families in Minnesota knew intuitively into something a new urban gardener in Detroit could apply.
The result was a document that treated cold storage the same way a mechanic treats a repair manual: here is the system, here are the variables, here is what happens when each goes wrong. It covered root cellars, basement storage rooms, outbuildings, outdoor pits, and apartment-scale alternatives. The fundamental science has not changed.
Primary Source
Storing Vegetables and Fruits in Basements, Cellars, Outbuildings, and Pits
U.S. Department of Agriculture, Bureau of Plant Industry, Soils, and Agricultural Engineering. Farmers' Bulletin No. 1939. Washington, D.C.: Government Printing Office, 1942.
Public domain — U.S. government work. Search the Internet Archive →
A companion document, USDA Home and Garden Bulletin No. 119, Home Storage of Vegetables and Fruits (1973), updated the guidance for the postwar suburban household, acknowledging that most readers no longer had basements or outbuildings. Both documents cover the same underlying science.
The Core Science
The 1942 bulletin organized all cold storage knowledge around two numbers: temperature and relative humidity. Every storage method described in the document is a variation on how to achieve and maintain specific combinations of these two variables.
Cold slows the enzymatic processes that cause spoilage. Most root vegetables require temperatures between 32°F and 40°F — cold enough to significantly slow respiration and microbial activity, but not cold enough to freeze the cells.
The bulletin documented freezing damage in detail: when cell walls rupture from ice crystal formation, the vegetable softens, weeps moisture, and begins rapid decomposition. The practical consequence is that outdoor pits in very cold climates required insulation — straw, leaves, or soil layers — to keep temperatures above 28-30°F even when ambient temperatures dropped well below zero.
A few crops prefer warmer storage: winter squash and pumpkins do best at 50-60°F. Sweet potatoes need 55-60°F. Onions and garlic tolerate a wider range. The bulletin organized crops by their temperature requirements, not alphabetically — a practical structure that tells you which crops can share a space.
Moisture control is where most household cold storage fails. Root vegetables lose moisture through their skins — this is a continuous process. In dry storage conditions, a carrot stored for three months will emerge shriveled, rubbery, and of low culinary quality even if it hasn't technically spoiled.
Most root vegetables require 90-95% relative humidity — near-saturated air. The traditional method for achieving this was packing vegetables in slightly damp sand, sawdust, or sphagnum moss. These media hold moisture around the vegetables without direct contact with free water. Direct contact with standing water causes rot.
Onions and garlic require the opposite: 65-70% humidity, dry enough to prevent the outer layers from softening. This is why onions and carrots cannot share a root cellar bin without compromising one or the other.
Storage Conditions
The following conditions come directly from the 1942 bulletin and the 1973 Home and Garden Bulletin, cross-checked against current USDA Agricultural Research Service guidance.
Group 1
32–40°F · 90–95% humidity
Pack in damp sand or sawdust. Keep in ventilated bins. Do not wash before storing.
Group 2
32–40°F · 65–70% humidity
Cure before storing (2–4 weeks at room temperature). Store in mesh bags with good air circulation. Keep away from apples.
Group 3
50–60°F · 70–75% humidity
Cure squash and sweet potatoes before storing. Store on shelves, not packed. Check monthly for soft spots.
Methods
The 1942 bulletin described six methods in order of structure required. Most households had access to at least two. The method used determined the temperature and humidity range achievable.
Root Cellar
The original system
A dedicated underground storage room, typically below the frost line, with ventilation vents to regulate temperature. The ideal root cellar maintained 32-40°F year-round and 90-95% humidity from the surrounding earth. The bulletin provided construction plans. Very few modern households have root cellars — but many older rural homes still do, and the technique remains viable for anyone with excavation access.
Basement Room
Most common 1942 method
An unheated corner of a basement, preferably on the north or northeast side, partially below grade. The bulletin recommended insulating the interior walls and ceiling of this corner from the heated house while leaving the exterior foundation walls exposed to the cold. Ventilation windows allowed temperature control. Bins of damp sand or sawdust maintained humidity. This setup is still achievable in older homes with unfinished basements.
Outdoor Pit
The rural backup
A cone or trench pit dug in well-drained ground, lined with straw, filled with vegetables, covered with more straw and then soil. The insulation kept temperatures above freezing in most winters. The primary disadvantage was access: once sealed for winter, vegetables could not be removed without disturbing the entire pit. The bulletin recommended making multiple small pits rather than one large one, so that each could be opened and emptied without disrupting the rest.
Modern Refrigerator
What most households use today
A refrigerator set to 38-40°F with the crisper drawer set to high humidity approximates root cellar conditions for the vegetables in Group 1. It is not equivalent — most refrigerators hold 5-15 pounds of root vegetables maximum, versus hundreds of pounds in a working root cellar — but it serves the same function for a household not trying to store an entire garden harvest.
What It Teaches
The 1942 bulletin's organizing insight — that storage is a systems problem, not a product problem — is the part that transfers most directly to a modern household. Cold storage fails because people don't understand that different vegetables require different conditions, or because they create the right temperature but not the right humidity, or because they store incompatible produce together.
The modern refrigerator handles what the root cellar did for most households. For the quantities most households actually grow or buy in bulk, a refrigerator set correctly — cold drawer for carrots and beets, warmer shelf for squash, mesh drawer for onions in cool pantry — covers the storage needs the bulletin addressed with entire rooms of infrastructure.
Where the bulletin becomes newly relevant is in the scenario of extended power outages. Refrigeration disappears. What remains are the older methods: cool rooms, outdoor cold, and insulated containers. Knowing that carrots can be stored for four months in damp sand at 35°F — and that this is not primitive folk knowledge but documented USDA science — is the kind of resilience information that becomes practical when infrastructure becomes unreliable.
The bulletin's attention to harvest timing, curing, and selection before storage is also directly applicable. The best root cellar in the world cannot salvage a vegetable that was harvested too late or damaged at harvest. The discipline of cold storage begins in the garden, not the cellar.
Further Reading
Farmers' Bulletin No. 1939 (USDA, 1942) — Internet Archive
The primary source. Full bulletin available in the public domain.
Food Self-Reliance — NWS
Growing, storing, and preserving food at home.
The Victory Garden Soil Method — Heritage
What the 1943 USDA knew about preparing soil for production — the step before storage.
Sources