Curing

Curing is a post-harvest conditioning process in which specific crops are held at defined temperature and humidity conditions for a period of days to weeks before long-term storage. It is not a preservation technique in the way canning or drying is - it doesn’t prevent spoilage through heat, dehydration, or chemistry. Instead, it prepares the crop’s own biology to support longer storage life.

The mechanisms differ by crop type, but the common thread is surface preparation: curing hardens skin, seals wounds from harvest, dries outer layers that would otherwise harbor decay organisms, and (in some cases) converts starches to sugars.

Garlic and Onions

Curing garlic and onions dries the outer papery skins and neck tissue, creating a barrier against fungal and bacterial decay. An uncured onion with a thick, moist neck is an invitation for neck rot (Botrytis allii). A properly cured onion with a dry, tight neck and hardened outer skins will store for 6-12 months.

Curing conditions:

• Hang or spread in a single layer in a warm (75-95°F), dry, well-ventilated location out of direct rain
• Duration: 2-4 weeks for onions; 3-6 weeks for garlic
• Garlic is ready when the wrapper skins are dry and papery, the cloves are firm, and the stems are completely dry
• Onions are ready when outer skins are fully dry, the neck is tight and brittle

Soft-neck garlic stores up to 12 months when properly cured and stored; hard-neck varieties 6-9 months. Uncured garlic stored damp will rot within weeks.

Winter Squash and Pumpkins

Curing winter squash and pumpkins hardens the skin, heals small cuts and scrapes from harvest, and continues converting starches to sugars (improving flavor). Delicata, butternut, acorn, and most winter squash benefit from curing; acorn squash is the exception (curing degrades acorn squash quality).

Curing conditions:

• 80-85°F, 80-85% relative humidity for 10-14 days
• A warm greenhouse, heated garage, or sunny indoor space after harvest
• Hard-skinned varieties like ‘Hubbard’ develop maximum storage life after curing: up to 6 months in proper cold storage

Inadequately cured squash - stored immediately in a cold cellar after harvest - may store for only 4-6 weeks before rotting.

Sweet Potatoes

Curing sweet potatoes heals the damaged skin and shallow cuts inevitable in harvest, develops the characteristic sweetness (starch-to-sugar conversion continues for weeks), and hardens the skin for long-term storage.

Curing conditions:

• 80-85°F, 85-90% relative humidity for 10-14 days
• Commercial production uses dedicated curing rooms; home growers use a warm indoor space with a damp towel or humidifier
• After curing: store at 55-60°F, 75-80% humidity. Do NOT refrigerate sweet potatoes - below 55°F causes a chilling injury that produces internal browning and off-flavors.

Uncured sweet potatoes store for only 2-4 weeks. Properly cured ones store 4-6 months.

Potatoes

Potatoes are cured at 50-65°F with high humidity (85-95%) for 10-14 days after harvest. Curing heals skin wounds (suberization - the formation of a corky layer over cuts) and allows damaged potatoes to be identified and removed before they infect storage. After curing, lower temperature to 38-40°F for long-term storage.

What Curing Doesn’t Do

Curing cannot save a crop that was harvested with significant rot or disease. It extends storage life of sound crop, not damaged one. Sort carefully during and immediately after curing, removing any soft, moldy, or bruised items that will infect neighbors in storage.