I've read about that in some of my older Rose books as well but have never done it.

Brendan: I read the link above and Minnesota has more snow which provides a thick blanket of insulation to protect roses. When I bought peonies from a nursery in Michigan, the lady wrote me a note, saying that if I have decent snow in winter, then add 1 planting zone .. so zone 5 becomes zone 6 if there is a thick blanket of snow for insulation. Sadly we have dry winter in Chicagoland (gave away my snowblower a long time ago !!). The neighbor sold his snowblower to make room in his garage.

I did potassium-feast, giving Frederic Mistral sulfate of potash in Sept., and the canes were huge, and roots got big& woody. But it died that dry winter with no snow plus dry spring. Potassium is plenty in alkaline clay, but it's NOT available under dry condition. Potassium is most available to plants in wet condition.

Straw, makes sense. Hopefully we get some decent snow this winter!

Do you think if you hand watered over winter, Frederic would have survived? Maybe I could make sure to water if winter is dry

Frederic Mistral seems a little tender here in zone 7, NC. My plant has had large areas of dieback in very cold winters but it recovered.