I saw this on pintrest and tried it out. It seriously WORKS!!! Its like I have a mini green onion garden on my windowsill in the kitchen! Love it!

The next time you have green onions, don't throw away the white ends. Simply submerge them in a glass of water and place them in a sunny window. Your onions will begin to grow almost immediately and can be harvested almost indefinitely. Make sure you periodically empty out the water, gently rinse off the roots and then refill with fresh water.