During the last week of June, I severely cut back three groups of perennials as a means to "clean them up", as all three had bloomed their asses off and were now looking tired and spent.
I knew they would bounce back rather quickly with nice clean foliage and some new blooms and I'm here today to show you that they came through with flying colors.
#1 - Tradescantia (Spiderwort) 'Sweet Kate':
After the the big cut back:
And how they looked about two weeks later:
And five weeks later ... :
... with some periodic re-bloom to boot:
#2 - Geranium 'Brookside':
The day of their haircut:
And as of this evening:
#3 - Nepeta (Catmint) 'Walker's Low':
And now sporting cleaner foliage and some blooms (not to mention the bees are back in droves):
While cutting back your perennials seems like a frightening proposition at first, I would actually be more frightened to leave them untouched. Trust me, it gets ugly.
If you chop them back (assuming you did your research and you know which ones are "choppable"), in two to three weeks time they will look better than they did right before they were snipped.
Remember, "Just prune it".