hello
they usualy take trimming well, and bounce back no problem.
I over wintered 2 last year.
goodluck with yours
michelle

And, you can offer cuttings for trade when you prune!!!!

They can be pruned at any time. In fact, pruning is recommended after blooming since blooms form on new growth.

Thanks for the advice. Somewhere I had heard you shouldn't prune them. I'm glad to get the truth. Happy gardening everyone.