Should You Throw Away Onions That Have Sprouted?

You reach into your pantry for an onion to dice up for tonight’s soup, and notice green shoots sprouting from the top. “Yuck!” you think. “This onion has gone bad!” Your first instinct may be to toss it straight into the compost bin, but wait- sprouted onions can still be safely eaten if used soon.

Onions are living plants that continue respiring after harvest. Given the right conditions like warmth and humidity, dormant buds will begin to sprout, signaling the onion’s attempt to keep growing. Many home cooks see this sprouting as a sign of spoilage and assume sprouted onions have somehow become toxic or dangerous to eat.

Close up of onion sprouts

The truth is, onions sprout in storage all the time, and not using them is simply a waste of good food. While sprouting does impact flavor and texture, sprouted onions can be used in many dishes as long as precautions are taken. This article will explore why onions sprout, how to identify if an onion has gone bad, and plenty of smart ways to use up sprouted onions before they go to waste.

This article is focussed on onions that sprout after being harvested. If you are interested in what to do with onions still in the ground, check my article on leaving onions to flower.

Why Do Onions Sprout?

Onions are biennial plants, meaning they take two years to complete their lifecycle. In the first year, onions form bulbs. If given the chance in the second year, they will sprout flowers and set seed.

When onions are harvested, growth is interrupted before this lifecycle can complete. However, the onions are still living plants with dormant buds that will sprout given the right conditions. There are a few key reasons harvested onions may begin sprouting in storage:

Storage Conditions

Onions last longest when stored in a cool, dry, dark place. Warm temperatures and humidity provide ideal conditions for sprouting. Storing onions in humid environments like a musty basement or near ripening fruit speeds up sprouting.

A wire basket filled with whole onions that have sprouted green tops

Onion Age

Older onions that have been in storage for several months are more likely to sprout than fresh onions. Their internal chemistry changes over time, triggering sprout production.

Onion Variety

Some onion varieties are more prone to sprouting than others. Yellow storage onions typically last longer than red or white onions before sprouting.

The Sprouting Process

When an onion sprouts, changes begin deep within the bulb. Cells in the onion’s inner rings start dividing and elongating into green shoots that emerge through the neck and outer scales. The sprouts originate from small dormant buds scattered throughout the fleshy rings.

Initially, just a single green shoot may emerge. But once the process begins, more sprouts will follow. If left to fully mature, these shoots would eventually produce flowers and seeds to propagate the next generation of onions.

Is it Safe to Eat Sprouted Onions?

The good news is that sprouted onions are completely safe to eat! The sprouts themselves are edible, and the onion bulbs remain good for use in cooking as long as the onion flesh is still firm.

Potential Changes in Flavor

That said, sprouting does impact an onion’s chemistry, so the flavor and pungency may be slightly different than a fresh, non-sprouted onion. As sugars convert to growth compounds, sprouted onions can taste stronger, spicier, or more bitter.

Caution Against Eating Rotten Onions

Onions that have advanced to the point of rotting should be tossed. Signs of rot include a soft, mushy texture and foul, musty odor. But until that point, sprouted onions are perfectly edible.

Bowl of chopped onions

Myths and Safety Concerns

Many people mistakenly believe that sprouted, green onions are poisonous or dangerous to eat. This is simply not true. The sprouts are an all-natural process and contain no toxins.

However, there are some valid safety considerations when handling spoiled onions:

  • Rotten, mushy onions may contain higher levels of bacteria that can cause food poisoning. Stick to firm bulbs only.
  • Moldy onions should be discarded, as mold can cause allergic reactions or illness in some individuals.
  • Onions sprouting thick green stems with flowers blooming on top are very mature and won’t taste good.

Other than these precautions, feel confident that sprouted onions are not toxic, poisonous, or dangerous to eat. Trim off the sprouts and use those firm bulbs as you normally would!

Letting Onions Flower

If you want to experience the full lifecycle of an onion, you can opt to leave onions in the ground to flower and set seed instead of harvesting the bulbs early. Here’s what to expect if you let your onions bolt:

Onion Flowers

In an onion’s second year of growth, a tall green stalk will emerge from the bulb and produce clusters of petite white, pink, or purple flowers. The blooms have a sweet, oniony scent.


Once pollinated by insects, the flowers develop into hundreds of tiny black onion seeds over summer. Seeds can be collected once the flower heads dry out and turn brown.

Bulb Quality

Allowing onions to flower reduces the quality and shelf life of the underground bulb. The energy spent on flowering makes the bulb mature faster with more pungent taste.

Identifying Sprouted Onions

It’s easy to identify onions that have started sprouting. Here’s what to look for:

Green Shoots

Emerging green shoots are the most obvious sign of sprouting. These delicate sprouts will originate from the onion’s neck area and may reach several inches in length if left to grow.

Softening Texture

As sprouting depletes the onion’s internal food reserves, the texture slowly becomes softer and thinner. The outside layer of paper-like skin will remain dry but the inner rings feel more wilted.

Foul Odor

A rotten, musty smell means the onion has gone bad and should be discarded. Trust your nose – if it smells funky, it’s done.

Comparing Onion Sprouts and Scallions

At first glance, the slender green sprouts may resemble scallions. However, scallions are an entirely different vegetable. The key difference is scallions are harvested young before a bulb forms. Onion sprouts emerge from a previously formed bulb.

Removing Sprouts

If you catch onion sprouts when they are small, simply snap or cut them off, leaving the firm bulb intact. Take care not to cut too deeply and damage the usable rings of onion flesh below.

For larger sprout clusters, trim back to the surface of the onion. Or, cut the root end off entirely – new sprouts won’t form from the remaining upper portion.

Storing Onions to Prevent Sprouting

To help your onions last as long as possible before sprouting, use these storage tips:

Ideal Storage Conditions

Onions keep best in a cool, dry, dark space around 40-50°F [4-10°C]. The ideal humidity level is fairly low, around 65-70%. Avoid warm, moist areas that will accelerate sprouting.

Well-Ventilated Containers

Store onions in breathable containers like mesh sacks or laundry baskets. Avoid sealing them in plastic bags, which traps moisture. Open-topped crates or baskets work well.

Remove Outer Layers

Peeling off the dried, papery outer skins before storage prevents the necks from drying out. This minimizes shriveling that can expose sprout buds.

Keep Separated

Onions release gases that speed ripening. Keep them separated from each other and store away from fruits like apples that also emit ethylene gas.

Canning or Freezing

For long-term storage, canned or frozen onions won’t sprout. Pressure canning whole peeled onions lets them last up to a year. Chopped onions can be frozen in bags for 6-12 months.

Other Tips

  • Buy smaller onions which sprout slower than larger bulbs.
  • Use older onions first and don’t over-purchase.
  • Check regularly and remove any sprouting onions.
  • Cut away roots and top to stop sprouts from advancing.

Following proper onion storage guidelines minimizes sprouting so you can enjoy fresh onions as long as possible!

What to Do With Sprouted Onions

Sprouted onions should be used as soon as possible before they go bad. Here are some great ways to put them to use:

Photo of thinly sliced white onions sautéing in an iron skillet

Cook Them

Sauté sprouted onions into stir-fries, frittatas, or omelets. The sprouts can be chopped up too. Roasting brings out the natural sweetness in sprouted onions. Add them to soups, stews, chili, etc. The moisture in cooked dishes softens any bitter notes.

Pickle or Caramelize

Pickling onions in vinegar masks any strong flavors. Caramelizing sprouted onions mellows their taste.

Use in Stock

Simmer sprouted onion trimmings or halves in homemade broth or stock. This infuses flavor and the sprouts soften into the liquid.

Mix into Salsa

Chopped sprouted onions add a punch of flavor to fresh salsas and pico de gallo. The acidity balances out bitterness.


If sprouted onions have softened or you won’t use them soon enough, place them into a compost bin. They’ll break down into nutrient-rich food for plants and gardens.

Other Ideas

  • Add to casseroles, pasta sauce, pizza, etc.
  • Dry sprouts for homemade onion powder.
  • Infuse vinegar or oil.
  • Make into onion jam.

With some creativity, you can take advantage of those sprouted onions instead of throwing them out!


In summary, don’t be too quick to discard those sprouted onions! With their green sprouts emerging, it may be tempting to assume they’ve gone bad and toss them out. However, sprouting alone does not make onions unsafe or inedible.

Onions sprout naturally as a result of storage conditions, age, and variety. Sprouted onions can be used in many cooked dishes, although their flavor may intensify. Only discard onions that have become mushy, moldy or foul-smelling.

Storing onions properly helps prevent sprouting in the first place. Keep them cool, dry, separated and in ventilated containers. Remove papery outer layers before storage.

Sprouted onions should be used promptly before they spoil. But they can still be enjoyed sautéed, roasted, pickled, or added to soups, stocks and salsas. With some creativity, those sprouted onions don’t have to go to waste!

Being more open-minded about produce imperfections like sprouts is an important step in reducing food waste. Respect your food, and your wallet, by finding ways to use up what you buy – sprouts and all!

Leave a Reply

Your email address will not be published. Required fields are marked *