You reach into the pantry basket and there it is: an onion with a bright green shoot poking out of the top, sometimes several inches long. The first instinct is to throw it out, the way you would a potato that’s grown long pale sprouts. But onions and potatoes don’t follow the same rules, and in most cases that sprouted onion is perfectly fine to eat. There are just a few things worth checking first, and one clever second life for it if you’d rather not cook it.
Sprouting is simply the onion doing what it’s designed to do. An onion is a bulb, a store of energy for the plant, and when it senses warmth, light or moisture, it starts using that store to grow a new shoot.
Is a sprouted onion safe?
Yes, as long as the onion itself is still sound. Unlike potatoes, which build up solanine in their sprouts and green patches, onions don’t produce a comparable toxin when they sprout. The green shoot is edible too: it tastes much like a scallion or chives, a little stronger, and can be sliced and used the same way.
What changes is the quality. As the shoot grows, it draws sugars and moisture from the bulb, so the flesh gradually becomes softer, less sweet and sometimes slightly bitter, especially near the center.
When to throw it out
The sprout isn’t the problem. These are:
- Mold: black, gray or fuzzy patches under the skin or on the layers.
- Mushy or slimy texture, or layers that have turned brown and wet.
- A sour or rotten smell instead of the usual sharp onion scent.
If only the outer layer is affected, peel it away and check the rest. If the softness goes all the way through, compost it.
How to use it
Cut the onion in half lengthwise and pull out the green core, which is usually tougher than the leafy shoot above it. Use the firm outer layers in cooking, where a slightly softer texture won’t matter: soups, stews, sauces and anything slow-cooked. Slice the green shoot like a scallion for garnish.
Or skip cooking it altogether. A sprouted onion planted in a pot of soil, with the shoot above the surface, will keep producing green leaves you can snip for weeks, a tiny windowsill harvest from something you almost threw away.
How to keep onions from sprouting
Onions like the opposite of the fridge: a cool, dry, dark and well-ventilated spot, in a mesh bag, a basket or a paper bag with holes. The one thing to avoid is storing them next to potatoes. Potatoes give off moisture that encourages onions to sprout and rot, and onions speed up spoilage in potatoes in return. The same pantry rules that keep potatoes from sprouting apply here, just in separate baskets.
Once an onion has been cut, it does belong in the fridge, wrapped or in a sealed container, and should be used within about a week.
A green shoot isn’t a death sentence for an onion. Check it, trim it, cook it or plant it. That’s the trick.
