Why Do Potatoes Sprout Eyes? (And When They're Unsafe)

Why Do Potatoes Sprout Eyes?

Potatoes sprout eyes because they are living tissue. A potato is not a root — it is a swollen underground stem called a tuber, and every one of those dimples on the skin is a dormant bud waiting for the right moment to grow. When conditions are right, those buds wake up and push out new shoots, turning your pantry potato into a potato plant. This is the same biological process that makes onions sprout and garlic send up green shoots.

The eyes are not a defect or a sign of spoilage. Every potato has them. They are the nodes of the stem, and each one contains a cluster of cells that can produce a new plant. In nature, this is how potatoes reproduce — the tuber stores energy underground through winter, then in spring the eyes sprout, pushing shoots up toward the light to form a new plant. We interrupt that cycle by harvesting and eating the tuber, but the potato does not know that. It keeps trying to grow.

What Triggers Sprouting?

Three things wake up the eyes: warmth, light, and moisture. Potatoes stored in a warm, bright kitchen will sprout fast, sometimes within a week or two. The ideal sprouting temperature is around 15–20°C, which happens to be typical Australian room temperature. Light is a strong trigger too — even indirect daylight tells the potato that spring has arrived and it is time to grow. Moisture, either from humidity or from washing potatoes before storing them, softens the skin and encourages the eyes to break dormancy.

Time is the fourth factor. Potatoes have a natural dormancy period after harvest that lasts several weeks to a few months, depending on the variety. Once that dormancy ends, sprouting is inevitable regardless of storage conditions. This is why potatoes bought in early spring, which may have been in storage since autumn, sprout faster than freshly dug ones.

If you want to keep your potatoes dormant for as long as possible, store them somewhere cool (around 10°C), dark, and dry. A pantry cupboard away from the oven is better than a bright kitchen bench. Do not store them in the fridge — cold temperatures convert potato starch to sugar, which makes them taste sweet and burn easily when fried. You can read more about this in our produce storage guide.

Why You Should Never Store Potatoes Next to Onions

One of the most common pantry mistakes is keeping potatoes and onions together. Onions release ethylene gas as they age, and potatoes are sensitive to it. The ethylene speeds up sprouting in the potatoes, while the moisture from the potatoes encourages the onions to rot. Both go bad faster than they would stored separately. Keep potatoes in a cool, dark, breathable bag (paper or hessian, not plastic) and onions in a separate, dry, ventilated spot.

Apples and bananas also produce ethylene, so keep those away from your potatoes too. If you have ever wondered why your potatoes sprout faster after a banana sits near them on the counter, this is why. Our guide to ethylene and ripening covers this in more detail.

Are Sprouted Potatoes Safe to Eat?

This is the question everyone asks, and the answer is: it depends. Small sprouts on a firm potato can be dealt with safely. Large sprouts on a soft, wrinkled potato are a different story.

When a potato sprouts, it starts producing solanine and chaconine — glycoalkaloid compounds that are toxic in high doses. These compounds are concentrated in the sprouts themselves, the skin around the sprouts, and any green patches on the potato. The flesh is generally lower in these compounds, but levels rise as sprouting progresses.

The practical rule is this: if the sprouts are small (under 1 cm) and the potato is still firm, you can cut away the sprouts and a generous chunk of the surrounding flesh, then cook and eat the rest. If the potato is soft, wrinkled, heavily sprouted, or has large green patches, throw it out. Cooking does not destroy solanine, so you cannot boil or roast your way out of the problem.

You can read more about solanine and the risks in our detailed guide on old potatoes and solanine poisoning, and our guide on why potatoes turn green.

Why Do Some Potatoes Sprout Faster Than Others?

Variety matters. Early-season potatoes like Kipfler and new potatoes have shorter dormancy and sprout faster. Main crop varieties like Sebago, Desiree, and Russet Burbank have longer dormancy and store for months. If you buy the same potatoes every week and find some sprout fast and some do not, it is often down to how long ago they were harvested and how they were stored before they reached you.

The age of the potato at purchase is a big factor. A potato that has been in cold storage for months before hitting the shelf at Woolworths is closer to the end of its dormancy than a freshly dug one from a farmers' market. If you are buying for long-term storage, ask when they were harvested, or scan the potato with PickFresh for a freshness assessment before you commit.

Can You Plant a Sprouted Potato?

Yes, and many home gardeners do exactly this. A sprouted potato is a potato that is ready to grow. Cut the potato into chunks, each with at least one strong sprout, let the cuts dry for a day, then plant them in the garden with the sprouts facing up. Each chunk will produce a new potato plant, and in a few months you will have a crop of new potatoes.

This is how potatoes are traditionally propagated — they are not grown from seed in most home gardens. Seed potatoes (which are just certified disease-free tubers, not actual seeds) are sold specifically for this purpose, but a sprouted potato from the pantry will work for a casual home crop. Just do not expect the exact same quality or yield as certified seed potatoes, which are grown for this purpose. See our potato harvesting guide if you want to go from planting to harvest.

How to Stop Potatoes Sprouting

Storage is the main lever. Keep potatoes cool, dark, and dry. Do not wash them before storing — moisture triggers sprouting and rot. Keep them in a paper or hessian bag, not plastic, which traps moisture. Store them away from onions, bananas, and apples. If you buy in bulk, check the bag every week and remove any that are starting to sprout so they do not trigger the rest.

Do not store potatoes in the fridge. Cold converts starch to sugar, giving potatoes an unpleasantly sweet taste and a tendency to burn when fried. The exception is if you want to make very crisp roast potatoes — some chefs deliberately cold-store potatoes for a week to boost the sugar content for better browning. For everyday eating, though, keep them out of the fridge.