If mine suffers winter freeze damage I trim it back but I wait to see where the new sprouts are before cutting anything. Most winters they handle the cold without problems but single digit nights can cause a lot of damage or even kill them.

Thank you for the info. I hope mine survived this winter.

...I've grown this here successfully and without dieback, and what we do, or supposed to do, is just tip prune some shoots after flowering, to keep the plant bushy...

Thank you so much for the information