This is how I have been getting my back yard to "green up". In the picture, it doesn't look as green anymore right? That is because I "scalped" it ... twice .. in opposite directions. I also do not bag the clippings, I mulch everything (it provides nutrients for the soil). I will also, very sparingly, spread my fireplace ashes with a broadcast spreader. I also put down a lot of lime.
Now, if we had been having a brutal hot summer, I wouldn't dare do this. It could do devastating harm to the grass. But .. this summer has been relatively mild with plenty of rain, so a good time as ever to prep it for vigorous re-growth by getting rid of the undergrowth. (this is the third time I have scalped the lawn this season)
Some of that is Kentucky Fescue, and some of it is Centipede grass and some is Bermuda. There is a mixture of different grass in my back yard, and I want it to be uniform. The Fescue is quickly overtaking the Centipede and Bermuda - which I want it to continue to do. Tall Fescue looks absolutely awesome IMO.
I have read and talked to a lot of "experts" that have said to never ever scalp Fescue. However, I have found that during mid-growing season during a mild season, Fescue will grow back with a vengeance. So - in about a week or so, I will show you what the lawn looks like.
Keep in mind .. 2 years ago .. there wasn't any grass back there - 15 pine trees and other weed trees were removed. It left a lot of mulch, weeds and orange mud.