Seil I tried some Knockout roses in pots. I like the yellow one because it has a nice fragrance..I did what you described. They did not survive.
I think people that get really cold and stay cold is better than the heavy rain we get then back to almost zone 4 weather for a few weeks.
I have tried maybe 40 different roses through the yrs all were grafted. All these were planted in the garden.
This order are own root roses. First time I have tried own root other than minatures roses,
