Once you have produced a bumper onion crop, we recommend these products to harvest and extend the shelf life of your endeavors. The key to keeping onions for a long period is to harvest them at the proper time. There are three things to look for that indicate proper curing: the neck, the roots, and the outside layer of skin. Of the three, the most critical is the neck; clip the tops off when you don't feel any moisture at the base of the neck when you rub it with your forefinger and thumb. Keep the onions in a well ventilated area.