Q.Native California roses
We planted a native rose which has done well —possibly too well. Its rhizomes launched several shoots barely through a four-foot-high bush, which we just cut to the ground. We found the shoots very leggy, single stem three feet long. I’d like to prune them back as short as possible to form full plants. Can I cut them, and how?
You can certainly prune them back now but being leggy may be a trait they will carry if they have gone to their wild side. Some folks make a notch in the long canes, put some rooting harmone like Olivia's Cloning Gel on it and then bend the cane down and bury it. Once it takes root you have another bush. Pruning the rosebush outright I would leave at least 20 inches of cane and try to be sure there are some leaf bud eyes on the remaining canes to help it leaf out and get going.