Some of my potatoes have a greenish tint to the skin. I’ve always heard that green potatoes were poisonous. What causes this? Are these potatoes edible? -Kay
It’s no old-wives’ tale – green potatoes contain a toxic chemical called solanine, a distant cousin of strychnine. However, you may be able to salvage your potatoes, and you can definitely prevent it from happening again. Here’s what you need to know to keep your potatoes brown and healthy.
Why Potatoes Turn Green
Potatoes turn green when they’re exposed to sunlight. As the plant prepares for photosynthesis and sprouting (by producing green chlorophyll), it develops a bitter, poisonous chemical (solanine) to discourage hungry animals from eating it. The green color serves as a warning that toxic solanine is present. Incidentally, the stems and leaves of potato plants also contain solanine, which is why we don’t eat the greens.
Causes of green potatoes:
- Erosion of garden soil exposing the growing tubers to sunlight.
- Being stored in a bright, sunlit kitchen or shed.
- Fluorescent lights in grocery stores.
So What About Solanine?
Solanine is a nerve toxin. In large quantities, it can cause headaches, nausea, vomiting, diarrhea, and even convulsions. As if that wasn’t enough, it also tastes bitter, so it ruins your recipes! The good news is, the quantities are low enough that you’d have to eat an awful lot of green potatoes to suffer the worst effects. Still, other than the occasional green-tinged potato chip, you need to avoid consuming green potatoes and especially avoid serving them to children.
How To Prevent Green Potatoes
- Hill Your Plants: In the garden, green potatoes mean there’s not enough soil. It’s customary to “hill” potato plants by mounding soil 4”- 6” high around the stems. Check your garden after rainstorms, to make sure the soil hasn’t washed away. Immediately cover any potatoes that start to poke out of the ground.
- Store in the Dark: In the kitchen, green potatoes mean there’s too much light. Store your potatoes in a cool, dark place. Don’t expose them to sunlight or to extremes of heat or cold.
Can Green Potatoes Be Salvaged?
If, despite your best efforts, you have the occasional greenish potato, you can usually salvage it if you cut or peel away every trace of green. If the potato skin is mostly green, or if it’s sprouting from the eyes, you need to throw it away.