I cut back my butterfly bush almost to the ground right at the beginning of spring. I live in the Northeast, Pittsburgh, PA to be exact. I have yet to see any growth. Did I cut it back too far or is it too early to tell.
Butterfly bush can be cut back completely to the ground with no ill effects. It's likely too early to tell whether it will resprout. If it fails to resprout, it's not the pruning job that killed it; instead it would be weather conditions over winter that are to blame.