If you store your onions right, they’ll stay fresh for several months. 

Onions are incredibly versatile. They can be pureed into soups, chopped up to add crunch to tacos or sandwiches, and add delicious flavor to just about anything. Because they can be used in so many dishes, it's a great idea to buy them in bulk. That means less trips to the store and potential savings at checkout. The other thing that makes onions a great candidate for buying in bulk is their long shelf life. According to the National Onion Association, onions will last an average of one to three months if you store them properly. If you want to make sure your onions will last as long as possible, this is what you need to know. 

Store Onions in a Well-Ventilated Place 

The National Onion Association says it's imperative to store onions in a well-ventilated area. Otherwise, they'll mildew quickly. If you buy your onions in a plastic bag, be sure to remove them as soon as you get home. A paper bag, basket, or cardboard box will provide better ventilation. Make sure they're stacked loosely so air will have a chance to circulate around them. 

Store Onions Somewhere Cool And Dry 

Whole onions will deteriorate faster if they're exposed to excess moisture. This means it isn't a good idea to store them in your refrigerator. According to the National Onion Association, the optimum storage temperature for onions is 45 - 55 degrees. A basement, garage, or anywhere where they'll be protected from heat or sunlight will generally be the best fit.  

Once you cut into an onion, however, you'll want to store the remainder in the refrigerator. If you put the pieces in an airtight container, it should last one to two weeks. 

Do Not Store Onions With Apples or Potatoes 

Potatoes release moisture, which will cause your onions to deteriorate more quickly. In addition, apples and potatoes are prone to absorb the pungent aroma of onions, so unless you want your apple pie to have a hint of onion, it's a good practice to make sure they are stored separately. 

How Do You Know if an Onion Has Spoiled? 

It's generally easy to tell if an onion is bad a glance. First, look for dark spots. This is usually a precursor to mold and a good sign your onion is starting to turn. A good onion should be firm to the touch. If you feel soft spots, the onion is past its prime. If your onion has started to grow sprouts, that is also an indication it has gone bad. Lastly, give it a good sniff. If it smells "off" then it's probably a good idea to dispose of it and reach for a fresh one instead.