Question
Instead of thatching, my lawn man set fire to my centipede grass (11 acres of it)
and burned the entire lawn.  Three weeks have passed with lots of rain and no
sign of green.  We live in S. Georgia.  Will the grass come back and if so, how
long will it take?  Should I just start over with all new grass seed or sod?  Help!

Answer
Your lawn man may have broken some local regulation against open fires; I do not know.
Under normal circumstances the lawn should recover but signs of such a recovery should have shown up by this time. After all, burning used to be a way to renovate pastures and may still be done in some parts of the world. I think that you should start planning to replace the lawn.