If you use a lot of spring onions (also called green onions, shallots or scallions), you may want to try this.
When you finish slicing off the greens, keep the white bulb (with its roots) and a little bit of the green part in a cup of water. Place this on a sunny windowsill. The onions will shoot up again and keep you well stocked through several re-growings.
Change the water every second day.
Cut pieces as you need them.
Here are my two bits
The chopped off bits
New greens sprouting