The method of overseeding a lawn is really nothing more than spreading grass seed over an existing lawn. This treatment is the easiest way of keeping grass young. As years go by, just like humans, mature plants reproduction rate begins to decline. Since a blade of grass lives approximately only 2 months, production of new tillers must continually outpace the dieback of older leaves. Young grass will produce tillers faster than older grass. Therefore, one of the most important ways to maintaining a healthy and thick lawn, is to make sure your grass is young. Also, before overseeding your lawn, you should mow your lawn short and bag the clippings. This will allow the seed to come into contact with the soil when it is spread.