Overseeding can be as simple as broadcasting a cool season grass seed over a warm season grass to achieve year-round color. At the opposite extreme, several inches of turf and soil could be entirely removed and replaced. Overseeding is popularly used to add winter color, thicken and repair damaged sports turf, and to incorporate improved varieties into the existing grass. Overseeding is best done in the fall but can be done any time of year. It is an excellent option for lawns that are healthy, with little damage, and where the intent is to maintain year-round appearance.
Renovation is a good alternative when fifty percent or more of the grass has been damaged.
This is a less severe, less costly approach than turf replacement. Renovation, like overseeding, is best done in the fall and requires the existing grass be killed but not totally removed. Dethatching and soil aeration follow to condition the seedbed for the new seed. Replacement is a major effort and is called for with old or diseased lawns or turf that are beyond saving. This is the most radical approach.