How Do I Store Sweet Potatoes After Harvest?

Fresh-harvested sweet potatoes are not actually at their sweetest — the starch-to-sugar conversion that gives cured sweet potatoes their characteristic flavour only develops over the weeks and months after curing and storage. A sweet potato stored correctly can last six to twelve months and improve in flavour throughout that time. A sweet potato stored incorrectly — too cold, too warm, in a wet environment, or uncured — may rot within weeks. The two-step process of curing followed by proper storage is not optional; it is fundamental to a successful harvest.

The curing process

Cure immediately after harvest. The curing environment should be warm (29–32°C) and humid (85–90% relative humidity) for four to seven days. A clean shed, polytunnel or greenhouse in a warm spell works well — place tubers in a single layer on paper, not touching each other, with good air circulation. In a cool autumn, a heated airing cupboard at 27–30°C with a damp cloth nearby for humidity is a practical alternative. Curing hardens the skin, heals harvest wounds (dramatically reducing post-harvest disease entry), and initiates the starch-to-sugar conversion that improves flavour.

Long-term storage conditions

After curing, store at 13–15°C in a dark, dry, well-ventilated place. A cool pantry, cellar or insulated garage is ideal. Do not store at temperatures below 10°C — chilling injury causes the flesh to harden, discolour internally and develop an unpleasant off-flavour, even when later cooked. Do not refrigerate sweet potato. Avoid temperatures above 18°C as this encourages sprouting and shrinkage. Store in boxes, crates or paper bags (not plastic — moisture trapped in plastic causes rot).

Preparing tubers for storage

Handle tubers gently at every stage — bruising and abrasion create entry points for rot. Do not wash tubers before storage: washing removes the natural protective compounds from the skin surface and increases rot risk. Allow any surface soil to dry and brush off gently before storing. Sort out any badly damaged, cracked or diseased tubers and use them first — do not put them into long-term storage as they will rot and spread to nearby tubers.

Checking stored tubers

Check every two to three weeks and remove any tubers that are softening, developing mould or showing disease symptoms. One rotting tuber in a box will accelerate deterioration in all the tubers touching it. A stored sweet potato that begins to sprout at one end is still perfectly good to eat — just cut off the sprout and use the tuber promptly.