How to Tell If a Potato Is Bad: 7 Clear Warning Signs

A bad potato shows clear signs: soft or mushy spots, green discoloration, strong unpleasant odor, excessive sprouting, or visible mold. Never eat potatoes with significant green areas or a bitter taste, as they contain toxic solanine. Properly stored potatoes last 3-5 weeks in a cool, dark place.

Spotting Spoilage: Your Complete Guide to Potato Freshness

Nothing ruins meal planning like reaching for potatoes only to discover they've gone bad. Knowing exactly how to tell if a potato is bad saves money, prevents food waste, and protects your health. This guide delivers the precise visual, tactile, and olfactory indicators you need to confidently assess potato quality.

Visual Warning Signs You Can't Ignore

Start your inspection with these critical visual cues that indicate spoiled potatoes:

• Green patches - Caused by light exposure, these areas contain solanine, a natural toxin
• Significant dark spots - Indicates advanced decay beneath the skin
• Excessive sprouting - While small sprouts are common, long sprouts signal aging
• Mold growth - Fuzzy white, green, or black patches mean immediate disposal

According to the USDA Food Safety and Inspection Service, potatoes with minor sprouting or small green spots can be salvaged by removing affected areas, but extensive greening requires complete disposal.

Tactile Indicators: What Bad Potatoes Feel Like

Your fingers provide crucial information when determining if potatoes have gone bad:

• Mushy texture - Gently press the potato; firmness indicates freshness while soft spots signal decay
• Wrinkled skin - Excessive wrinkling means moisture loss and advanced aging
• Hollow areas - When squeezed, bad potatoes often feel less dense with potential hollow spots inside

Condition	Safe to Eat?	Recommended Action
Minor sprouting (1/4 inch)	Yes	Remove sprouts before cooking
Small green spots	Yes	Cut away green areas completely
Extensive greening	No	Discard entire potato
Mushy texture	No	Compost or discard
Visible mold	No	Immediately discard

The Critical Smell Test: When Potatoes Signal Danger

Fresh potatoes have an earthy, neutral scent. Trust your nose with these guidelines for identifying rotten potatoes:

• Sour or musty odor - Indicates bacterial growth
• Bitter smell - Warning sign of high solanine levels
• Ammonia-like scent - Clear indicator of advanced decomposition

The National Center for Home Food Preservation notes that potatoes developing off-odors should never be consumed, even if visual signs appear minimal. Your sense of smell provides early warning before visible spoilage occurs.

Understanding Solanine: The Hidden Danger in Bad Potatoes

Green potatoes contain solanine, a natural defense compound that becomes toxic at high levels. Symptoms of solanine poisoning include:

• Nausea and vomiting
• Headache and dizziness
• Abdominal pain
• In severe cases, neurological symptoms

The FDA states that concentrations above 20mg per 100g can cause illness. Peeling removes about 30% of solanine, but extensive greening requires complete disposal.

What to Do With Questionable Potatoes

Not all imperfect potatoes need immediate disposal. Follow these professional kitchen guidelines:

• Slightly sprouted potatoes - Remove sprouts and "eyes" with a knife; safe to eat if firm
• Minor green spots - Cut away affected areas plus 1/4 inch around them
• Soft spots - Excise affected areas if limited to small sections
• Wrinkled but firm potatoes - Best used for mashed potatoes or soups

When in doubt about if potatoes are bad, follow the chef's rule: "When you have to ask, throw it out." Better safe than sorry with potential foodborne illness.

Preventing Potato Spoilage: Pro Storage Techniques

Extend your potatoes' shelf life with these evidence-based storage methods:

• Store in a cool, dark place between 45-50°F (7-10°C)
• Use ventilated containers like paper bags or wicker baskets
• Never refrigerate - Cold temperatures convert starch to sugar
• Keep away from onions - They release gases that accelerate sprouting
• Check regularly - Remove any spoiling potatoes immediately

Research from the University of Idaho Extension shows that properly stored potatoes maintain quality for 3-5 weeks, compared to just 1-2 weeks under suboptimal conditions.

When to Toss Potatoes: Clear Disposal Guidelines

Discard potatoes immediately if you notice any of these signs of spoiled potatoes:

• More than 25% of the surface shows green discoloration
• Strong bitter taste during cooking
• Extensive soft or mushy areas
• Visible mold growth
• Unpleasant odor

Remember that cooking doesn't destroy solanine, so green potatoes remain unsafe even after preparation. When evaluating how to tell if potatoes have gone bad, prioritize safety over saving food.

Can you eat potatoes with small sprouts?

Yes, potatoes with small sprouts (under 1/4 inch) are safe to eat if firm. Simply remove sprouts and 'eyes' with a knife before cooking. However, extensive sprouting indicates aging and reduced quality.

Why do potatoes turn green and is it dangerous?

Potatoes turn green when exposed to light, producing chlorophyll and solanine. While chlorophyll is harmless, solanine is a natural toxin that can cause nausea, headaches, and digestive issues. Potatoes with significant greening should be discarded entirely.

How long do potatoes last before going bad?

Properly stored in a cool, dark place, potatoes typically last 3-5 weeks. At room temperature, they may only last 1-2 weeks. Refrigeration isn't recommended as it converts starch to sugar, altering flavor and texture.

Can you cut the bad parts off a potato and eat the rest?

Yes, for minor issues like small green spots or sprouts. Cut away affected areas plus 1/4 inch around them. However, if more than 25% is affected, or if the potato feels soft/mushy, discard the entire potato as toxins may have spread internally.

What's the best way to store potatoes to prevent spoilage?

Store potatoes in a cool (45-50°F), dark, well-ventilated place like a paper bag or wicker basket. Never refrigerate, and keep away from onions which release gases that accelerate sprouting. Check regularly and remove any spoiling potatoes immediately.