My uncle use to grow great big onions, the hamburger slab size. But he's passed away two years, before I got started in the garden stuff. This years onions were decent sized, but I would like to get some of the bigger size. We think he use to stomp on the onion stems, but not sure if that is the key. They were always big by the 4th of July. Does anybody have any opinions on this? Any help would be greatly appreciated. Thank you.