I saw this on Pinterest and decided to give it a go. Simply take the stubs (ends) of the spring onions and place them in a cup. You can add some kitchen towel so they don’t topple over. Add water to them.
As you can see, their roots quickly start to grow. They all start out like the top left one.
2-3 weeks later:
Voila! And you’ve saved yourself a bit of money. They aren’t quite ready yet, but they will be soon!