A friend showed me this trick and I think its too cool not to share. Supermarket green onions (and any other bulbing scallion) will put out new green onion when immersed in water. And it happens remarkably quick — less than a week from immersion to more usable green. Which means one bunch of onions can last you a very long time if properly tended…. water should be changed in the jar every five days or so. I am pretty sure that the bulb can’t be forced eternally but this technique certainly does stretch out their edible life!