The optimal lawn seeding window is mid-August to mid-September. If you missed that time frame, but you still want to seed this fall, my recommendation is to wait until November to seed. This practice is called dormant seeding and is certainly an effective way to introduce new species and/or varieties of turf into your existing lawn.
By far our most popular post on this site has been the one on this topic, so we are re-posting an article originally published on November 1, 2013.
If you are considering dormant seeding, read on to start planning for November: There’s Still Time to Dormant Seed Your Lawn.