Is it ok to prune back my knockout roses as early as the last week of September? We will be gone for the winter. Or should I wait until we come back end of April to prune them? I'm talking about cutting them back to about 20 inches from the ground. I am in SE Michigan. Thank you.

Moved to the Rose Forum

Better to wait until April so you don't encourage new growth right as roses need to be shutting down for winter.
to the Rose forum!

And !

Thanks for that information. I was wondering the same about mine but I live in 7b.