Take a good look at your lawn, if it looks like its thinning out or weak, over-seeding may be your answer. When you overseed, you plant seeds directly into the already existing turf without tearing up the soil or turf. You may be thinking that applying sod can do the same trick but it may not give the same results. This is because when you overseed, you get a thicker, more beautiful lawn for a fraction of the cost if you used sod. Overseeding also keeps away weeds if it is mowed over 2 inches tall. It also keeps disease away because any new variety of seed sown today will have better resistance to disease than those seed varieties already existing in your lawn. The early fall is the best time to overseed but you can also get good results in the spring.