Ok mine turned out super heavy hard to water and takes like 60 plants per tower! DIY Saturday – Make Your Own Flower Tower- This would be a centerpiece, gift idea for a gardener or a house warming idea!
This article titled "How To Grow Sprouted Onions" at Alternative Gardening talks about exactly that. I had no idea. All this time, if I didn't eat an onion in time, I would simply plant the whole thing as-is in the soil.