Hi and welcome to the forum. I took the liberty of moving your question about grass seed to the Lawn Care Forum, where a lot more people will see it who might be able to answer your question.
However, I don't think anyone will be able to answer it until you tell us whether you are in Portsmouth Ohio, New Hampshire, Rhode Island, Virginia, Oregon, or England (or I'm sure there's some I missed). It makes a big difference.
Preferably tell us where you are and what USDA hardiness zone you are in, and/or when your frost usually starts in the fall.
The more info you can give us, the better answers we can give you!