Spoiled onions may develop dark spots, which will eventually begin to grow mold. You'll also want to avoid onions that have started sprouting, as this indicates they're beginning to go bad. You can also feel your onions to check how fresh they are. Onions with soft or mushy spots are starting to go bad.
How long do onions last? According to The Chef's Garden cookbook, onions stored at temperatures between 30°F and 50°F will keep for up to one year. Otherwise, they'll last for several weeks. Store cut onions in the refrigerator (or even the freezer)…
For onions, the sprout grows through the center of the bulb. The good news is the sprouts are safe to eat. They do have a tendency to taste a bit bitter, however.
Peeled onions can be stored in the fridge for up to two weeks, while diced or sliced onions will only last for 7–10 days (4). Avoid storing whole, unpeeled onions in the fridge, as they easily absorb moisture. Doing so may cause them to become mushy and spoil faster.
Spoiled onions may develop dark spots, which will eventually begin to grow mold. You'll also want to avoid onions that have started sprouting, as this indicates they're beginning to go bad. You can also feel your onions to check how fresh they are. Onions with soft or mushy spots are starting to go bad.
Store in a Cool, Dry Place
For this reason, he says it's best to store onions in a cool, dry place like a cellar, pantry, or even a garage. While they can be stored whole in the fridge, Yee notes that this causes the onion to convert starch to sugar, and can result in soft or soggy onions.
THE BOTTOM LINE: Cook sprouted onions as soon as possible after the sprouts appear, since the flavor and texture of the onion will only continue to deteriorate. And that green bit? Resist the temptation to use it in your food; garnish the compost pile with it instead.
You should plant the seedlings just 1″ into the ground and space them at least 4″ apart so the bulbs have room to grow. Planted onion sprouts will take about 3 weeks to look perky. Keep them watered and plant them in a place that gets plenty of sun.
USDA Foods say when an onion is chilled, the cold temperatures convert the starch to sugars, meaning onions become soft and soggy a lot faster than they otherwise would. Oh, and that they make everything else taste/smell like nasty onions, and no one wants that.
Don't wash your onions or garlic before you store them. Keep them very dry. While in Storage Check and cull them often to make sure the onions and garlic are not sprouting or developing soft spots. Remove and eat any damaged bulbs.
If you notice a green sprout emerging from the top of an onion, it means it's trying to regrow. By separating the sprouts inside an onion's layers and planting them in good soil you can grow multiple new onions within a single season.
Store in a cold, dry, dark place
The optimal storage is 35 to 40. But be sure to protect them from freezing, if they freeze and then thaw they will start to rot. If you only have a few onions a fridge isn't a bad option. But if you have 50 or more then you need to find a cool spot.
How do you keep onions from rotting? It's all about proper storage: Keep the onions away from sunlight, in a cool, dry, well-ventilated spot. Any environment that fosters moisture will result in onion spoilage.
Best practice is to store eggs in the fridge; that way the temperature is always at a constant and your eggs will be fresher!
Any moisture that gets trapped around the onions will promote early spoilage, so good air circulation is key, as is removing thm from plastic produce bags, if you use those to gather them at the store. Place the container in a dry, dark spot, like in the back of your pantry or inside a cabinet.
Storage rots are caused by fungi and bacteria (Pseudomonas and Erwinia spp.) that live on organic matter and onion debris in the soil. These organisms are common in soil and will attack several different host plants. They become a major problem wherever onions are grown in a short rotation.
If you have onions without a label or sticker, or that you don't know the source of, throw them out. Wash any surfaces and containers that have come in contact with onions with hot soapy water or in the dishwasher.
Keep Onions Away from Apples and Potatoes
"In general, don't store ethylene-sensitive fruits or vegetables with fruits or vegetables that produce a high amount of ethylene gasses," says John Adler, the vice president of culinary at Blue Apron.
Once the onion tops and roots have fully dried, you can tidy 'em up by trimming the roots and cutting off the stems with garden scissors. A couple layers of the outside skin will usually flake off with the stems, leaving you with a clean, smooth onion.
Whole onions keep for 2 to 4 weeks at room temperature and more than 3 months if refrigerated. No matter the storage spot, onions need good airflow, so they don't grow mold. After cutting, onions keep for 4 to 7 days in a sealed container in the fridge.
As long as it does not have that intense rotting smell, you can safely remove the affected layers and continue to use the parts of the onion that are white.