Here in CT we’re overseeding the last week of September, so you should be ok in mid-October, depending on the seed you are using. We’re using KBG and perennial rye. We’ll aerate first, and put down a starter fertilizer. Water enough to keep it moist until it germinates and gets established a bit.

Rye germinates in 1 week. Fescue germinates in 2 weeks. Kentucky bluegrass germinates in 3 weeks. Had you started this in August (killing the crab), you could have reseeded this month and used October to evaluate whether you needed to fill in any thin spots.

So give it a try. You will not have a second chance this season. Don't get tempted to seed in the spring, because that's what causes crabgrass to go wild.

One time i seeded Tall fescue- when the nighttime lows were in the mid 40's, and it germinated just fine. I couldn't believe it.........it totally blew my mind up !