Every autumn I go to a pick-your-own farm and harvest several bags of onions. This is how I keep them fresh for use throughout the following months. If done correctly, stored onions using this method should last ten months.
After drying the onions and trimming the roots, place the onions in the pantyhose, separating each by a knot.
Find a pair of discarded pantyhose, or buy an inexpensive pair like the ones above purchased for $1.47, and then cut them in half.
The final step is to store the onions in a cool, dry place away from sunlight, such as a store room or garage, depending upon your environment. When you need an onion, just cut the bottom one off below the knot.