Potatoes may indeed rot in cold, wet ground, but imagine my surprise
this spring when a few "volunteer" potatoes showed up in last years
potatoe row! Obviously I hadn't quite gotten them all.

My suggestion would be for you to try it out and see what happens!

I have:
a) the worlds worst draining soil - at least 90% clay (proven by the
fact that I can kill with the dried clods laying about)
despite MASSIVE amounts of green manures. compost, regular ol' manure,
rye grass (you get the picture)
b) zone 4b-5a (is there such a thing? right on the border, as it
were)

On the other hand, my attempt at overwintering spinach (supposedly a
no-fail cropper) under protection failed miserably; only one plant out
of a couple short rows actually made it into spring. Seeds sown in
the fall to germinate in spring.

Good luck to ya!