I plant spring onions from sets every year. They are usually the first things to pop out of the ground. Then, after about a month, they are mature enough to pluck from the soil and eat as delicious, tender spring onions.
But I never pull them all up. A few get a little too plump for raw, spring onions, so I leave them alone. By July, the green tops have disappeared, and it looks like the onions have left the building. But they haven’t. They wait until September when things cool off, then resume growing.
A week or so ago, I needed another vegetable for my meal and thought roasted onions would be nice. Then I remembered my little patch of rejuvenated onions. I pulled up about a dozen, maybe the size of golf balls, peeled off the top layers of onion skin and roasted them in the oven with a little olive oil and they were delicious, a real winter garden treat. I may leave even more in the ground next year.