I was skeptical when I heard this on Food Network, but I'll be darned if it doesn't work like a charm.
After you chop the green end off of your green onions, put the roots in a cup of water. Almost immediately (no kidding) the green stalks will begin growing again. I think mine grew an inch overnight.
So, if you use a lot of green onions in your food (like we do) start "recycling" your green onions instead of tossing the roots and buying more.
I took this photo right after I put the onions in the cup (about 8pm on Friday night). The tops were about as tall as the top of the cup, maybe just a bit higher.
This photo was taken Sunday morning, just 2 days after I put them in the cup!