The only way to keep the size of these plants in check is to prune them in the spring when you start to see some green growth, usually at the bottom of the plant. Mine have gotten awfully large since I've not cut them back for a couple of years. Our winters have been somewhat mild and there has been little die-back on the branches from the last two winters.

Linda

About halfway up the picture, you could draw a line between the fat, healthy growth and that which should be trimmed - just below the wall behind it. After that, remove the tips of the lower branches, which should also remove all of the dead flowers from last year. Then look at it from different sides and trim anything that is sticking out too far, or growing across the middle.

Most of the removed parts can be rooted to make more bushes.

Also, I never prune mine until spring, here in the colder zone 6, because the bush needs all the help it can get going into the winter. I wait for new growth to just start showing in spring and then prune it.

Yours looks fantastic! Great job! Those pieces on the ground each want to grow a new bush for you... (enable, enable...)

Mine were green all winter and one of them has buds that should open in the next few days. It's wild how early everything is happening in most places. I swear when I lived in OH (5b), it was the norm for BB's to just start showing leaves about this time, mid-April. Am I remembering correctly?

Since BB's produce buds on old and new growth, and they do it rapidly all summer, there shouldn't be any fear about removing buds or delaying flowering, especially in this, the year without a winter. Even mid-summer when I'm deadheading, I'm very generous with the cuts when I see weaker, smaller buds in front of a much more robust node, and usually remove that inferior set. Once the branches get too long, they seem to lose their oomph. Still end up with a bush that's taller than me.

So far so good, and I expect it to bloom this year (but high expectations), we'll see!