'Home grown' green onions

A couple of weeks ago, I saw something on Pinterest about regrowing green onions...so I figured what the heck, I'd give it a try.  

I'd bought a bunch for some recipe, but only used a little bit from the top end.  So the instructions said just to put the bottom ends in water, and they'll grow. 

Before...

And after.  It freaking worked. 

And now I understand why they are sold chopped and with rubber bands!  The stalks are crazy and going everywhere.  I've changed the water a couple of times, just when it starts to look a little murky.  I'm not sure that I'll be able to keep them for ever, but at least maybe I won't have to buy green onions quite as often!