Commented: Cat businessCritter Ridder (pepper pellets), mothballs or bitter apple spray usually work. There's also motion sensitive sprinklers & ultrasonic alarms.
Once you've gotten rid of the cats, you'll be back to ...
Commented: need suggestion: red companion perennial for switchgrassyarrow isn't floppy if you ring it about 4 inches up... the ring gets hidden by the foliage. 5' grasses? you'll want something substantial. a small shrub might be a better choice.
