I have two Bangor Blackberry plants that have survived -32 F without
winter protection.
You may remember that I reported about my blackberry trials in 2009 and
mentioned that none of the Bangor plants survived here in zone 3 unless they
were weighted down and covered with snow. I destroyed all of those plants
but kept a few suckers that I transplanted to study how they perform over
time. Now I've got two plants that are probably worth propagating.