Green onions, also called scallions, are a versatile ingredient that's included in many recipes. They add both flavor and color to a dish, can be cooked or eaten raw, and used as a garnish. So it would make sense to keep them on hand, but, unfortunately, they can turn limp and slimy before you get around to using them. This is often due to improper storage. By using one of three methods for storing green onions, you'll find that they'll last days longer than if they were simply placed in the refrigerator. This avoids food waste and avoids wasting your grocery money, too.
All you need to store green onions and keep them fresher longer is a jar, plastic bag, and paper towel. Before proceeding with any method, be sure to remove all packaging materials from the scallions.
Store on a Windowsill
As we don't need to store other types of onions in the fridge, it seems logical that it's not necessary to store green onions in the refrigerator. This method calls for storing on a windowsill. Put the onions in a heavy-bottomed jar that is tall enough to hold the scallions without them flopping over. Place the green onions root-side down and fill the jar with an inch or two of cold or room temperature water (just enough to cover the roots). Then simply place the jar on the windowsill in your kitchen. Your onions will not only stay fresh but will also continue to grow. Change or add water every couple of days, as needed.
Store in the Refrigerator
If you don't have a windowsill in your kitchen, you can store green onions in the fridge following the same directions for storing on a windowsill, but then covering the tops of the onions with a plastic bag—this can be the bag they came in or a zip-top bag.
You want to keep some of the humidity within the bag, so you need to cinch the bag a bit. If using the grocery bag, place a rubber band or string around the bag where it meets the mouth of the jar; for a zip-top bag, just close each side a little bit. You don't need an airtight seal, just enough to keep in the humidity. Once in place, store in the refrigerator. Just be sure to put the jar where it isn't likely to get knocked over, and remember to replace the water every couple of days.
Store in a Damp Paper Towel
Instead of placing the scallions in a jar, you can use a paper towel and storage bag. First, wrap the green onions in a slightly damp paper towel. The dampness provides the humidity needed for proper storage; if the towel is too wet though, it can promote rotting. If you prefer, you can sprinkle the towel with water after wrapping the green onions. Place the wrapped scallions inside a plastic bag or storage container; it doesn't need to be sealed airtight. Remoisten the paper towel if it dries out and replace it if it becomes too wet.
Keep Onions Past Their Prime
If you have onions lying around that are deteriorating, you don't have to throw them out. You can employ a few different methods that will actually cause them to regrow. First, cut off one inch of the green part of each onion (keeping the white part with the roots intact) and plant in your garden or in a pot on your windowsill, root-end buried in the soil. Any time you need some green onion, snip off some of the tops, leaving the white part with the roots planted in the ground. The onions will grow back again, and you can keep doing this as long as you don't disturb the roots. In many places, green onions will even survive the winter.