How to Tell If a Sweet Potato Is Bad: 5 Clear Signs

A sweet potato has gone bad when it shows significant mold growth, feels excessively soft or mushy throughout, emits a sour or unpleasant odor, or has large dark, discolored spots that penetrate deep into the flesh. Minor surface wrinkles or small sprouts don't necessarily mean it's unsafe to eat.

Discover exactly what to look for when checking your sweet potatoes—learn the critical difference between normal aging and dangerous spoilage that could make you sick. This guide gives you the practical, science-backed knowledge to confidently assess sweet potato freshness, reduce food waste, and protect your health.

Spotting Spoilage: Your Visual Inspection Checklist

When you reach for a sweet potato, your eyes provide the first critical assessment. Unlike regular potatoes, sweet potatoes have unique spoilage indicators you need to recognize immediately.

Start by examining the entire surface under good lighting. Healthy sweet potatoes maintain a firm texture and consistent color—typically deep orange, purple, or white depending on the variety. As spoilage begins, you'll notice these visual red flags:

• Mold growth appearing as fuzzy white, green, or black spots
• Significant darkening beyond normal surface blemishes
• Excessive wrinkling indicating advanced moisture loss
• Leaking liquid or wet spots on the skin
• Sprouting beyond small, isolated growths

According to USDA food safety guidelines, surface mold on dense vegetables like sweet potatoes often indicates deeper contamination you can't see. When in doubt, cut away a small section to check the interior condition.

Spoilage Progression Timeline: What Happens as Sweet Potatoes Deteriorate

Sweet potatoes don't spoil overnight—they progress through predictable stages. Understanding this timeline helps you catch problems early and reduce unnecessary food waste:

Stage	Timeline	Visible Signs	Action Required
Fresh	0-1 week	Firm texture, smooth skin, vibrant color	Store properly for maximum shelf life
Beginning to Age	1-3 weeks	Minor wrinkles, small sprouts, slight softening	Use within 2-3 days; cut away minor imperfections
Advanced Spoilage	3-4+ weeks	Significant soft spots, dark discoloration, surface mold	Discard immediately—do not consume

This progression timeline comes from research conducted by the University of California's Postharvest Technology Center, which tracks produce deterioration under various storage conditions. Temperature significantly affects this timeline—warmer environments accelerate spoilage.

The Critical Touch and Smell Test

Visual inspection alone isn't enough. Your sense of touch and smell provide essential confirmation:

Texture assessment: Gently squeeze the sweet potato. It should feel solid with minimal give. Dangerous spoilage shows as:

• Wet, mushy areas that leave indentations
• Sections that feel hollow when tapped
• Overall softness rather than firmness

Odor detection: Bring the sweet potato close to your nose. Fresh sweet potatoes have an earthy, slightly sweet aroma. Warning signs include:

• Sour or fermented smells
• Vinegar-like odors
• General unpleasantness beyond normal earthiness

The FDA emphasizes that odor changes often indicate bacterial growth that might not be visible. If something smells "off," trust your instincts and discard the sweet potato.

When to Save vs. When to Toss: Practical Decision Guide

Not all imperfections mean immediate disposal. Use this practical framework to minimize food waste while staying safe:

Safe to eat after trimming:

• Small surface wrinkles with firm interior
• Isolated sprouts less than 1 inch long
• Minor surface blemishes that don't penetrate deeply

Discard immediately:

• Mold covering more than 10% of the surface
• Multiple soft spots or overall mushiness
• Dark discoloration extending more than ¼ inch deep
• Any sour or unpleasant odors

Food safety experts at the National Center for Home Food Preservation note that sweet potatoes contain natural sugars that accelerate bacterial growth once the skin barrier is compromised. Unlike some vegetables, they don't have significant natural preservatives to slow spoilage once deterioration begins.

Maximizing Freshness: Storage Best Practices

Proper storage dramatically extends sweet potato shelf life. Follow these evidence-based methods:

Ideal storage conditions:

• Temperature: 55-60°F (13-15°C)—never refrigerate raw sweet potatoes
• Humidity: 85-90% relative humidity
• Ventilation: Allow air circulation around each potato
• Light: Complete darkness

For most home kitchens without ideal root cellar conditions, store sweet potatoes in a cool, dark pantry in a paper bag with ventilation holes. Never store them near onions, which release gases that accelerate sweet potato sprouting.

Refrigeration causes chilling injury that leads to hard centers and off-flavors. If you've accidentally refrigerated sweet potatoes, use them within 3-5 days as quality deteriorates rapidly.

Common Questions About Sweet Potato Freshness

These frequently asked questions address the most pressing concerns home cooks face when evaluating sweet potato quality:

Can you eat sweet potatoes with small sprouts?

Yes, sweet potatoes with small sprouts (under 1 inch) are generally safe to eat. Simply remove the sprouts and the small area beneath them. The rest of the sweet potato remains edible if it feels firm and shows no other signs of spoilage. Larger sprouting indicates advanced aging and potential quality deterioration.

What causes black spots inside sweet potatoes?

Black spots inside sweet potatoes typically indicate either internal bruising from handling or the early stages of decay. Small, isolated spots can be cut away safely. However, if the black areas are soft, spreading, or accompanied by an off smell, the entire sweet potato should be discarded as it's likely developing bacterial or fungal infection.

How long do sweet potatoes last in proper storage?

When stored properly in a cool, dark place with good ventilation, sweet potatoes maintain peak quality for 3-5 weeks. Under ideal root cellar conditions (55-60°F with 85-90% humidity), they can last 2-3 months. Refrigeration significantly reduces shelf life due to chilling injury, while warm conditions accelerate sprouting and spoilage.

Is it safe to eat sweet potatoes with minor surface mold?

No, surface mold on sweet potatoes indicates potential internal contamination. Unlike hard cheeses or firm fruits, sweet potatoes' dense structure allows mold to send invisible threads deep into the flesh. The USDA recommends discarding the entire sweet potato if any mold is visible, as cutting away the affected portion doesn't guarantee safety.

Why do sweet potatoes get hard in the middle when stored incorrectly?

Hard centers in sweet potatoes typically result from chilling injury caused by refrigeration. Cold temperatures below 50°F trigger chemical changes that cause certain starches to convert improperly, creating hard, uncooked areas even after thorough cooking. This doesn't indicate spoilage but significantly affects texture and flavor quality.