The most important factors for proper onion storage are good air circulation, relative dryness and cool temperatures. Look for an appropriate area in your home that has these conditions. Store your onions in small quantities and make sure they are safe from freezing.
You should periodically inspect the onions for damage and disease. Be careful to use or discard any onions that show signs of problems. If you want to use the onions, simply cut away the infected area and use within a few days. Onions that begin to feel soft to the touch may start to rot quickly. You may want to send these onions to the compost pile rather than using them.
In order to properly store onions, they must be well ripened and cured. Those that are immature, soft, or â€œthick neckedâ€ should never be placed in storage but used as soon as possible. Properly stored onions should be hard and may even rattle almost like wooden blocks when poured from one crate to another.
For the bulbs to remain bright and attractive, they should not be allowed to lie exposed to the weather, but should be stored in cool, dry areas as soon as possible.
In handling onions it is a good idea to pass them over a screen to catch any of the loose skins and to remove any of the soft, decaying bulbs.
Another good option for storing onions is to tie them up in bunches and store them by hanging them upside down in a cool, dry place.
Note that the stronger flavored onions last longer in storage than the sweet onion varieties. Try using all your sweet onions no later than two months after placing them in storage.