I don’t grow them, but they are everywhere here. Even after multiple freezes as cold as the lower 20s, the Knockout roses are deep green, and a few still have flower buds.
To me these seem really semi evergreen…only reluctantly defoliating after a freeze in the teens…sometimes as late as the New Year in MD. Have you seen the same thing?
The marketing usually says “blooms until first frost” but “first hard freeze” would be more accurate!
I only have a couple here in north Georgia but your description is accurate to their behavior. No disease problems either but one is very much liked by Japanese beetles. The flower is fragrant not sure if that is why
They do get “rose rosette” disease. (Be happy if yours don’t have it.)
Yes I’m aware of that one. I imagine it’ll come someday I’ll just pull the roses out I’m liking hardy hibiscus in their place but Japanese beetle love them too!!