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What Happens to a Potato in the Sun?

Potatoes (Solanum tuberosum) are common and productive vegetables for home gardeners. Starchy and high in nutrients, they last a long time in storage if properly handled. Store potatoes in the dark, both in the garden and after harvest, to keep them safe to eat. Potatoes exposed to sunlight develop a toxin that's harmful to humans and animals.
  1. About Potatoes

    • Potatoes are edible members of the nightshade family. The vegetables that we eat are enlarged root segments called tubers, starch-storing structures that allow the plant to live from year to year in warm climates. Each tuber contains latent growth points, called eyes, that send out new stems and roots under the right conditions. Occasionally, potato plants also produce above-ground fruit along the stems in addition to the below-ground tubers. Discard the above-ground fruit, since they're unfit to eat.

    Potatoes and Sunlight

    • Potato tubers exposed to light, whether artificial or natural, produce chlorophyll and turn green. The chlorophyll is harmless, but it indicates that the potato has also produced solanine, a bitter but colorless alkaloid harmful to humans and animals. Large amounts of solanine affect the nervous system and can cause death.


    • Always remove and discard any portion of the potato that has turned green. In addition, remove the eyes from potatoes, since they contain a large amount of solanine, even if the rest of the potato appears fine. Also, discard potatoes that have begun to sprout or are no longer firm. Don't add green potato peelings, sprouted potatoes or over-ripe potatoes to your compost pile if you use the finished product on your vegetable garden.


    • The old gardening practice of mounding soil around potato plants is still good advice. Adding extra soil over the plant stems and roots ensures that developing potatoes have a soil cover deep enough to prevent solanine formation. Alternatively, mulch your potato plants heavily with straw, adding extra as the season progresses and the first layer settles. In the kitchen, store potatoes in a dark pantry.