I do have a question: how can I tell which grass is currently growing? I think that the above picture is virtually all bluegrass.  Given the way that I have had the canopy of my trees raised, I am wondering if I could go with just the Spitfire from this point forward.  In any case it looks absolutely beautiful. Thanks for your help.

Tim W, Memphis, TN 

My answer: 

Tim:  I can't tell elite tall fescue from elite bluegrass in photos The plants look really similar now days. If it was my lawn I would get down and root around looking for long rhizomes.  That would be an indication of bluegrass.

I would let Mother Nature decide what, if any, seed to use in the future.  If there is enough light to support lush bluegrass, and Spitfire proves to be as heat tolerant as we expect, you probably won't need to overseed. If the lawn thins out over time perhaps a combination of my new SS1002 tall fescue shade blend with a little Spitfire would be appropriate. 

Drew