When you plant a dormant onion, it typically sprouts out several onions. With a mass producing onion such as a potato onion, you will get more than just a few onions. The question that remains is can the onion survive your winter in sprouted form.

Onions can break every rule in the book, but in general, short day onions, the type that does well down South, grow over the winter and go dormant in the peak of summer. Long day onions, the type that do well in the North, go dormant in the winter.

Most potato onions available these days are long to medium day so planting them in spring may be the right choice.

Onions greens will survive our worst here in 8b but that is about 20 degrees. Your results may vary. I have heard of people covering them with straw, but I have no real experience with onions in zone 6

Bob