Calculate Planting Dates to Overwinter Crops for Spring Harvest https://www.johnnyseeds.com/growers-library/vegetables/overwintering-planting-chart.html
I had a patch of scallions in NY that kept self seeding and overwintering with no planning or work on my part.
Come spring, the plants would look like a mess, the leaves all slimy and rotten looking. If I tried to pull them, they would mush and fall apart.
But accidentally, since I did not feel like touching slimy onions leaves, I let them go one year and they started growing again and within a couple weeks were healthy looking plants. The bulbs did divide and mr. mm said the flavor was a little different than more freshly sown scallions, but they worked very were and were very potent.
After that, I usually just left the scallion patch go and do it’s thing and I’d have great scallions very early in the year.
However, it does help to sow scallion seeds in that area two years in a row so that every year you’d be getting overwintered scallions.