patandchickens
Deeply Rooted
Munstead is by repute the cold-hardiest (I keep meaning to try it). Having good free-draining soil, as it sounds like you do, will help a lot.
Just try a plant or two -- they are not expensive, just stick 'em in your most plausible spot (preferably something with good snow cover in winter, and you can mulch 'em heavily once the ground freezes, too) and see what happens.
I think people often take catalogs/books' hardiness ratings too seriously. I am basically USDA zone 4 here, but there are zone 4 things I don't appear to be able to grow due to winter damage, and I have had a zone 7 (!) perennial looking very happily hardy in the particular places it's planted for several years now.
Most plants are cheap. Experiment
Pat
Just try a plant or two -- they are not expensive, just stick 'em in your most plausible spot (preferably something with good snow cover in winter, and you can mulch 'em heavily once the ground freezes, too) and see what happens.
I think people often take catalogs/books' hardiness ratings too seriously. I am basically USDA zone 4 here, but there are zone 4 things I don't appear to be able to grow due to winter damage, and I have had a zone 7 (!) perennial looking very happily hardy in the particular places it's planted for several years now.
Most plants are cheap. Experiment
Pat