Here is how i regrow green onions and leeks in the water.
The green onion was cut pretty short and this is after a week of growth in the water. I have been cutting parts and pieces and have been using them in my food already.
By planting my kitchen scraps, i am also teaching my children that they don't need to run to the store for the smallest thing. They can plant things and it could grow. Not every thing has to be bought.
I forgot to take a photo at the day one. But here is another photo two weeks and some cuts later.
Try it and let me know your result.