Try it. It turns out, at least for me, cold hardy plants do better
than tender plants under the snow or much better under a pile of soil
and then snow. Plants come out of hibernation early in the spring
and don't like being buried. When uncovered, here in spring it can
easily be 60 F and then 0 F a few hours later. This is when tender
plants die.
>When you speak of bending over canes of blackberries so they get snow
>cover
>why should the variety have to be particularly cold-hardy when
>treated this
>way? I bet you could grow Navajo in a zone 3 if you bent the canes
>over and
>covered with leaves before temps got below 10 F. or so.