All About Onion
Your complete guide to onion - discover how to store it properly, identify when it's gone bad, and find the best substitutes for your recipes.
How Long Does Onion Last?
Storage times and freshness tips for onion in different conditions.
Safety first: This guide provides general information. When in doubt, throw it out! Trust your senses and err on the side of caution. If something smells, looks, or tastes off, don't consume it.
cut or peeled (refrigerator)7-10 days
Signs of Spoilage
Sliminess, strong pungent odor (more intense than fresh cut onion), discoloration (yellowing, browning, or dark spots), fuzzy mold growth.
How to Check
Visually inspect for any changes in color or texture. Touch the surface – it should not feel slimy. Smell it – a sharp, sour, or overly pungent smell indicates it's gone bad.
Storage Tips
Store in an airtight container or a tightly sealed plastic bag to prevent drying out and to contain their strong odor from affecting other foods in the fridge. The pungent odor of cut onions can intensify over time, but it's the sliminess and discoloration that are true indicators of spoilage.
frozen (freezer)6-8 months (raw, chopped), up to 12 months (blanched or sautéed)
Signs of Spoilage
Significant freezer burn (dry, discolored spots), off-odor (unlikely if properly frozen), changes in texture making them overly mushy even when thawed.
How to Check
Visually inspect for excessive ice crystals or freezer burn. While a slight change in texture is normal after freezing, they should not be completely disintegrated or smell sour. If the smell is off, discard.
Storage Tips
For best results, chop onions into desired sizes. Raw onions can be frozen directly, but blanching for 1-2 minutes or lightly sautéing them before freezing can help preserve their texture and flavor better. Spread in a single layer on a baking sheet to freeze individually, then transfer to freezer-safe bags or containers, removing as much air as possible to prevent freezer burn. Label with the date. Frozen onions are best used in cooked dishes as their texture softens significantly upon thawing.
cooked (refrigerator)3-4 days
Signs of Spoilage
Sour or off-odor, visible mold, sliminess or mushy texture, unusual discoloration (darker than initial cooked state, green/black spots).
How to Check
Smell for any sourness or unpleasant odors. Look for mold or unusual colors. Touch to check for sliminess.
Storage Tips
Allow cooked onions to cool completely before transferring to an airtight container. Refrigerate promptly within two hours of cooking to prevent bacterial growth. Label with the date to keep track of freshness.
whole, unpeeled (pantry/room temperature)1-3 months (yellow/red onions), 2-4 weeks (sweet onions), 1-2 weeks (green onions/scallions are different and need refrigeration, but assuming standard bulb onions here)
Signs of Spoilage
Soft spots, dark patches, mold growth (especially around the root or neck), a strong, unpleasant sulfurous odor, sprouting (though sprouted onions can often still be used if firm), excessive moisture or sliminess.
How to Check
Visually inspect for any discoloration, mold, or sprouts. Gently squeeze the onion – it should feel firm all over. A soft or squishy spot indicates spoilage. Smell it – it should have a mild onion aroma; a very strong, foul, or sour smell is a bad sign.
Storage Tips
Store in a mesh bag, basket, or open bowl to allow air circulation. Avoid storing in plastic bags, which trap moisture and accelerate spoilage. Keep away from potatoes, as both release gases that can cause the other to spoil faster. Do not store in the refrigerator as the humidity can make them soft and moldy faster.