For those of you who aren't superintendents, dormant seed- also called frost seeding- is the placing of seeds outside of their normal growing window. And while late summer is the optimal time to seed most turf, dormant seeding typically yields better results than spring seeding (high rain levels can thwart attempts to establish a seedbed).
To dormant seed, first remove any material that may interfere with the seeds coming into contact with the ground. Then seed using about 25% more than you would in the late summer; weeds will still be an issue when the grass begins to grow, but herbicide applications offer enough control to allow the grass to get its footing. Of course, there are a lot of other factors and concerns when frost seeding, so check out the article below.