Question
When is it to late to sow grass in Tennessee

Answer
Hi Gary, Unless we get an unusually early cold spell, I consider the absolute last date to plant fescue in east TN to be Nov 1, middle TN Nov. 10th and west TN Nov 25th, but the earlier the better.  The sooner it get's established, the less likely a freeze will heave it out of the ground.  Ground temperatures may be warm enough for the seed to come up after these dates, but your success dwindles as the cold approaches.
Warm season grasses (bermuda, etc.) are planted May 1 - July 1.  Jim