Clint - Mowing them down WILL affect their performance the following year. I am in TN also. I would recommend cutting the foliage down to 6 inches. Just use scissors or hedge trimmers. That way they can continue to get sunlight and store energy for next years blooms. Primal Scream and Ruby Spider should bloom at least three weeks, if not more. Try some fertilizer in the early Spring next year. You likely don't have rust or leaf streak. Foliage just starts looking ratty this time of year.
