Overseeding: Over time, grass does get old and needs to be replaced. Worn-out lawns invite weeds. Reseeding is a fast, inexpensive way to bring your lawn back to its lush, green, healthy self without tearing everything out and starting over. It's also a great way to introduce a new type of grass. If you live in the south, you may want to reseed your Bermuda grass lawn with perennial rye grass for a green winter lawn.