From the ArcaMax Publishing, Gardening Newsletter:
http://www.arcamax.com/news/gardening/s-156710-689144
Question: I live in Tennesse. What type of grass is there that stays
green all year round. Right now my lawn is Bermuda grass, and it turns
brown in the fall.
Answer: Turf grasses are divided into two categories: warm and cool
season grasses. Warm season grasses do well where summers are hot,
but, as you've noticed, they go dormant when the temperatures cool.
There's no grass I know of that will stay green year round (except
Astroturf!), so the solution is to overseed your lawn sometime in
September or October with an annual, cool-season grass, such as annual
ryegrass or a fine fescue. Dethatch and aerate the lawn first, then
reseed, and top-dress with compost. When weather warms in spring,
dethatch and aerate again to stimulate the Bermuda to get growing. A
quicker method is to "scalp" the lawn by using a heavy duty reel mower
(you can rent them). This will remove most of the Bermuda tops. Rake
up the debris, sow your seed, topdress, water and fertilize. For the
best cool-season turf variety in your region, contact your County
Master Gardeners or ask a lawn care professional.