How to Tell If a Potato Is Bad: Key Warning Signs

To tell if a potato is bad, check it in this order: firmness, skin color, sprouts, mold, odor, and leaking or damaged areas. A firm potato with a few short sprouts is usually salvageable after cutting away the sprouts and eyes, while a potato that is green over a large area, moldy, wet, very soft, or foul-smelling should be discarded.

The safest decision depends on how much of the potato has changed and whether the remaining flesh is firm, dry, and normal-looking. When in doubt—especially with a strongly green, rotten, or moldy potato—throw it away rather than trying to rescue it.

Quick decision guide: keep, trim, or discard?

How to tell if a potato is bad: a six-step inspection

1. Feel the potato for firmness

Start with a gentle squeeze. A good potato should feel firm and dense for its variety, with a relatively tight skin. A little surface wrinkling usually means moisture loss and age, not automatically dangerous spoilage, but a potato that bends easily, feels spongy, or collapses under light pressure is a poor candidate for trimming.

Pay attention to whether softness is localized or widespread. A single hard, dry bruise can often be removed. General softness, a waterlogged texture, or a hollow-feeling potato points to deterioration throughout the tuber and is a reason to discard it.

2. Inspect the skin for green color

Green skin is one of the most important warning signs. The color develops when a potato is exposed to light and reflects chlorophyll formation; it can occur alongside higher levels of naturally occurring glycoalkaloids such as solanine and chaconine. The green pigment itself is not the entire risk, so do not treat a green potato as equivalent to an ordinary surface bruise.

If the green area is small and shallow, peel well below it and cut away all green flesh. Check the cut surface in good light. If green remains, if the green area is broad, or if the potato tastes unusually bitter, discard it. The U.S. Department of Agriculture and food-safety authorities commonly advise discarding potatoes with extensive greening rather than relying on cooking; ordinary boiling, baking, or frying should not be treated as a dependable way to remove these compounds.

3. Check sprouts and eyes

Sprouts are not the same as mold. A firm potato with one or two short sprouts may still be usable. Remove each sprout completely, then cut around and below the eye with a paring knife. Do not simply snap off the visible tip, because the eye and nearby flesh are the area to remove.

Use a more conservative standard when sprouts are long, numerous, or accompanied by wrinkling and softness. As a practical guide, a firm potato with sprouts shorter than roughly 1/2 inch (1.3 cm) is easier to assess and salvage than one covered in several-inch shoots. The measurement is not a guaranteed safety cutoff; texture, greening, and odor matter more than an exact length.

Never eat the sprouts themselves. If removing them leaves only a small amount of usable potato, discard the tuber instead of trying to save a thin remnant.

4. Cut open suspicious spots

Wash the potato under running water, scrub off visible soil, and dry it before cutting. Cutting after washing prevents dirt from being dragged through the flesh. Use a clean knife and a stable cutting board, especially if the potato has a deep crack or damaged skin.

Look at the cut surface. Normal flesh should be relatively even in color and firm. A small brown, dry, or bruised section can usually be removed with at least 1/2 inch (1.3 cm) of surrounding flesh when the remainder is firm and odor-free. That margin is a practical kitchen precaution, not a laboratory guarantee.

Do not trim around a wet cavity, slimy patch, spreading discoloration, or soft rot. If the potato releases liquid or the damage extends deeply, discard it. A knife can remove visible damage but cannot confirm that decay has not traveled through moist tissue.

5. Smell the potato

A sound raw potato has a mild earthy or neutral smell. A sour, fermented, musty, chemical-like, or rotten odor indicates that it should not be used, even if the exterior looks acceptable. Odor is particularly useful when the potato is inside a bag or stored beneath other vegetables, where one spoiled tuber can be overlooked.

Do not taste a suspicious raw potato to decide whether it is safe. Bitterness can accompany excessive glycoalkaloids, and tasting is unnecessary when visual or odor clues already indicate a problem.

6. Check for storage damage and neighboring potatoes

Inspect potatoes that have been stored in a dark cupboard, pantry, cellar, or garage for leaks, condensation, insect damage, and contact with a rotten potato. A damp bag or pooled liquid is a warning that spoilage may be affecting more than one tuber.

Remove any obviously rotten potato immediately and examine the others individually. Do not rinse all potatoes and return them wet to storage; moisture encourages decay. Keep sound potatoes dry, dark, and ventilated, ideally in a breathable paper or mesh bag rather than a sealed plastic bag.

When is trimming a potato safe?

Trimming is most reasonable when the problem is small, dry, and clearly localized. Examples include a shallow cut from harvesting, a firm bruise, a small sprout on an otherwise firm potato, or a limited green patch that can be removed completely with deep peeling. After trimming, the remaining potato should be firm, normal in color, and free of unusual odor.

Trimming is not a good rescue method for mold, wet rot, widespread softness, a strong bad smell, or extensive greening. Soft foods contain moisture pathways that can allow contamination to extend below the visible surface. For that reason, food-safety guidance generally favors discarding moldy soft produce rather than cutting off a small visible patch.

If you trim a potato, use the rest promptly and cook it thoroughly as part of normal food preparation. Do not store the trimmed piece for several more weeks, because cutting exposes moist interior flesh and shortens its storage life.

Worked example: deciding what to do with a mixed bag

Imagine a 5-pound bag containing 12 medium potatoes:

• Seven are firm, dry, and free of green color: keep them and store them properly.
• Two are firm with one short sprout each: remove the sprouts and eyes, then use those potatoes first.
• One has a 1-inch dry bruise but otherwise firm flesh: cut away the bruise with surrounding margin and cook it soon.
• One is green over roughly half its surface: discard it rather than trying to peel a large amount away.
• One is soft, leaking, and sour-smelling: discard it and inspect the neighboring potatoes.

This approach saves the potatoes that have a clear, localized quality defect without treating a visibly rotten or broadly green potato as recoverable.

Storage practices that prevent bad potatoes

• Block light: Store potatoes in a dark cupboard or pantry. Light encourages greening and sprouting.
• Allow airflow: Use a paper sack, cardboard box with ventilation, or mesh bag. Avoid sealed plastic for long storage.
• Keep them dry: Do not wash potatoes before storage. Wash them immediately before preparation instead.
• Avoid heat and temperature swings: A cool, stable, well-ventilated location slows sprouting. Very cold storage can alter starches and produce a sweeter taste, while warm storage accelerates sprouting.
• Separate ethylene-producing produce: Keep potatoes away from onions and ripening fruit where practical. Ethylene exposure can affect sprouting and storage quality, while excess moisture remains the more immediate spoilage concern.
• Rotate stock: Put newly purchased potatoes behind older ones and inspect the bag weekly during warm or humid weather.

Storage life varies by variety, harvest condition, and environment, so a calendar is less reliable than a regular inspection. In a cool, dark, dry, ventilated home location, sound potatoes may last several weeks; a warm kitchen may shorten that considerably.

Common mistakes when checking potatoes

• Assuming cooking fixes everything: Heat is not a reliable solution for extensive greening, mold, or rot.
• Removing only the sprout tip: Cut out the entire eye and surrounding area, not just the visible shoot.
• Confusing a bruise with rot: A dry, firm bruise can be different from a wet, spreading, foul-smelling soft spot.
• Returning trimmed potatoes to long-term storage: Once cut, use them soon and refrigerate prepared pieces in a covered container.
• Keeping a rotten potato in the bag: One leaking potato can spread moisture and decay to its neighbors.
• Tasting to test safety: Smell, appearance, and texture provide enough information; tasting is not necessary.

Frequently Asked Questions

Can you eat potatoes with small sprouts?

Usually, a firm potato with a few short sprouts can be used after removing every sprout and the surrounding eyes generously. Discard it if it is also green, soft, badly wrinkled, bitter-smelling, or covered with long sprouts. Use the trimmed potato promptly rather than storing it for an extended period.

Are green potatoes safe if you peel them?

A small, shallow green patch may sometimes be removed by peeling deeply and cutting away all remaining green flesh. If greening is extensive, reaches deep into the potato, or remains after peeling, discard the potato. According to food-safety guidance, ordinary cooking should not be relied upon to make a broadly green potato safe.

Can you cut mold off a potato and eat the rest?

Do not rely on trimming when the potato is soft, wet, moldy, or foul-smelling. Mold can extend below the visible surface in moist foods, so the safer choice is to discard the entire potato. A dry soil mark is not the same as fuzzy mold, but it should still be washed off and inspected.

What do bad potatoes smell like?

Bad potatoes may smell sour, fermented, musty, chemical-like, or rotten. A normal potato has a mild earthy smell. If the odor is clearly unpleasant or remains after washing and cutting, discard the potato without tasting it.

Can you eat a potato with a soft spot?

A small, dry, firm bruise can often be cut away when the surrounding flesh is normal, odor-free, and not discolored. A wet, slimy, spreading, or collapsing soft spot is a sign to discard the whole potato. When softness affects much of the tuber, trimming is not a reliable solution.

How should potatoes be stored so they last longer?

Keep them unwashed, dry, dark, and well ventilated in a cool, stable location. A paper or mesh container is preferable to a sealed plastic bag. Inspect them weekly, remove any leaking potato promptly, and use older potatoes before newer ones.