We’ve been experimenting for some time with harvesting a second and even third crop of scallions simply by placing the roots in water. You can place them on a window sill and grow a second batch quite easily. They won’t grow to the same length and girth as the originals, but, hey, it’s free scallions and who doesn’t like free scallions?
And if you are more ambitious, you can transplant them in soil as well.

In fact, why stop at green onions? How about celery? Sherry has set up this experiment and it seems to be working; we will keep you updated.
Now, you may notice in this photo not only scallions and celery, but cilantro. This is not a transplant in progress. You can also keep these types of greens fresh for days, simply by placing the roots in a bit of water.
The advantage to this approach vs. refrigeration is that they stay a bit more crisp and don’t become dehydrated.
Give it a try and let us know what you think.