Cutting back perennials in the fall
I have planted perennials I never had before. I don't know if I should cut them back in the fall like we do for hostas and others. They are: Jupiter's Beard, Gaura lindheimeri, Golden Groundsel (rudbekia), bugleweed, aster, serbian bell flower, wormwood-Powis Castle, Chrysanthemum.
Certified GKH Gardening Expert
I'm listing links for the plants you mention.
You generally can leave most perennials to die off themselves. I choose to leave some for winter interest, Black Eyed Susan is quite lovely in the winter.
Cutting the plants back to about 4 to 6 inches in height at the end of the season can help neaten up the garden and make spring clean up easier.
This will help with pruning and winter care.