Here's some good news, BlueGardner: Photos of Pierre Ronsard were posted by Chelle, Cottage_Rose, and Paul2032, all of whom are gardening in zone 5, and one of the listed owners of the rose is living in zone 4. A photo was even posted by 4susiesjoy, who gardens in zone 3. No one in the Denver area, unfortunately, but a good sampling of low USDA zones.