How long do sweet potatoes last before they go bad?

Stored somewhere cool, dark and dry — not the fridge — a raw sweet potato typically keeps for around three to five weeks, sometimes longer if it was well cured before you bought it. That is a shorter window than a regular potato usually gets, and the fridge makes it worse in a more direct way than it does for a regular potato: cold does not just change the taste here, it can injure the sweet potato itself.

The name is doing a lot of misleading work

A sweet potato is not a potato that happens to be sweet. Regular potatoes belong to the nightshade family, the same family as tomatoes and peppers; sweet potatoes are a member of the morning glory family and are not closely related at all. They just ended up with the same English word, and that shared name is most of the reason people assume one set of storage rules covers both. It does not. The two vegetables fail in different ways, on different timelines, for different reasons — and the fridge, in particular, treats them almost oppositely.

Why the fridge does more damage here

Regular potatoes tolerate a cold fridge without being harmed; the downside is purely a taste one, an enzyme converting starch to sugar faster than intended. Sweet potatoes do not get off that lightly. Below about 12–13°C — noticeably warmer than a normal fridge, not just below freezing — a sweet potato can suffer what is usually called chilling injury: the interior can turn hard and woody even after long cooking, an off, sometimes bitter taste develops, and the flesh becomes more vulnerable to internal decay once it warms back up. Unlike the potato's sugar conversion, which is a quality issue you can live with, a chilled sweet potato with a hardened core is not something a hot oven fixes. The damage happens whether or not anything looks wrong on the outside, which is what makes it worth knowing about in advance rather than discovering it in the middle of cooking one.

What curing is, and why it matters even though you cannot do it yourself

Freshly dug sweet potatoes are thin-skinned and bruise easily. Growers typically cure them right after harvest — holding them warm and humid for a week or so — which thickens the skin, heals small cuts from harvesting, and converts some starch to sugar, all of which meaningfully extends how long the sweet potato keeps and improves how it tastes. Most sweet potatoes sold in supermarkets have already been through this process before you ever see them, which is part of why a bag from the shop usually outlasts one bought directly from a farm stand a day after digging. There is nothing to do with this at home beyond knowing it happened — it is not a step you can add later — but it explains why storage life varies more for sweet potatoes than for most vegetables even when everyone is following the same advice afterward.

What spoilage actually looks like

Soft or mushy patches. A firm sweet potato with one soft, giving spot, especially near an end, is the earliest common sign — the surrounding flesh is usually still fine, but the clock has started.
Shriveling and wrinkled skin. This means moisture loss, not danger, but a sweet potato that has visibly shrunk is well past its best and drying out from the inside as well as the outside.
Sprouting. Like a regular potato, small shoots at the ends are common and are not, by themselves, a reason to throw the whole thing out — they are worth trimming away at the point of cooking rather than treating as a verdict.
Mold, leaking, or dark wet spots. This is the point of no return. A sweet potato that is oozing, has visible fuzzy growth, or has gone soft and dark rather than firm and shrunken should not be trimmed and used — the decay usually runs further into the flesh than it appears from outside.
A sour or fermented smell. Trust this over how it looks. A sweet potato that smells off has usually gone further than the outside suggests.

What actually helps

A cool, dark, ventilated spot — not the fridge, and not somewhere warm either. Roughly 13–16°C is the sweet spot: cool enough to slow spoilage, warm enough to avoid chilling injury. A pantry shelf or a cupboard away from the oven usually lands in that range better than a countertop or a fridge does.
Open storage, not a sealed bag. A paper bag, a basket, or a loosely closed container lets the moisture a sweet potato gives off escape instead of sitting against the skin and encouraging rot.
Away from onions. The same ethylene-and-moisture logic that applies to regular potatoes applies here — keep them stored apart even if they get bought and carried home together.
Buy roughly what the next few weeks will use. Three to five weeks is a real window, not a floor, and it shortens for any sweet potato that had a rough trip from the shop — bruised, damp, or left in a hot car for a while.
If it must go in the fridge, cook it first. A cooked sweet potato refrigerates the same as any other cooked vegetable and is genuinely fine there for a few days — it is the raw sweet potato that the cold actually damages.

The practical problem is rarely knowing the rule — it is remembering which cupboard a bag went into and how long ago, especially once it drifts from the pantry to wherever there was space that week. Munch lets you log an item against where it is actually stored, pantry included, so a bag of sweet potatoes carries an honest age that everyone in the household can see, rather than depending on whoever bought it to remember.

None of this needs memorising beyond the one distinction that matters: a sweet potato is not a cold-loving vegetable wearing a potato's name. Keep it cool rather than cold, dark rather than damp, and it will comfortably outlast the few weeks most people need from it.