I just took part in an interesting discussion on one of the Garden Stew forums.
One of the other gardeners there ask if she can top (trim) her onions.
I made a little research, and apparently it is possible to prune the tops of the onions – and help the bulbs grow bigger.
When you trim the tops you just grasp the leaves and cut them with a sharp scissor about four inches from the point where the onion enters the soil. Then you should just repeat this procedure regularly, in order to keep the leaves at about four inches.
Some gardeners say that this pruning helps the bulb of the onion to grow bigger and not run to seed.
Many gardeners have had problems with their onions this year. But if you grow onions it might be worth a try to prune the tops.