Shade Gardening: Your Woodland Shade Favorites 3, 1 by DonnaMack

DonnaMack wrote:
I have never cut them to the ground. They are fully hardy in my rather cold zone. I just let them start leafing out and then cut the old wood. Here is what the deal wood looks like - you can see it at the tips. I'm glad you wrote this now because I was just about to prune it.

I was moving, so I actually put the whole plant in a pot and kept it in my garage over the winter.

The second picture is from last May of 2010. You'll see a bit of dead wood on the left.

Unless they are so overgrown that they are scraggly and need renewal pruning, you probably can just prune them rather than cutting them to the ground. They will bloom earlier.