Somewhat like a weed, they will triple their own amount every year. They are called walking onions because they plant themselves. Just look how many we got just from planting a small bundle in this one area.
When the plant reaches the end of it’s cycle, it will start to grown onion bulbs at it’s tips. You can eat these miniature onions, or plant them to get a bunch more. If you do nothing, the bulbs will plant themselves within the same area.