I planted Varsity onions from seed and harvested the majority in August in my zone 5 Massachusetts garden. I noticed a few today and was surprised that they were not rotten. They were healthy and had vigorous roots attached. I found the taste to be sweeter and more tender compared to my summer harvested crop. I am wondering if some gardeners intentionally leave onions in the ground for winter harvest like leeks? I am very fond the flavor and texture of December leeks. Perhaps certain varieties of onions would be more suited for freeze-thaw cycles in late fall and early winter?