Yes, you can overseed fescue into a centipede lawn, but it is not easy. When we moved into our house (Durham), the builder had layed centipede sod. I went the whole summer with centipede at 2.5" tall, until late August. Over the course of two weeks, I mowed the centipede every 2-3 days, slowly dropping the blade each time, until I had it 1-1.25" tall. The aggressive cutting shocked the growth and since we were headed into a cooler period, it never was able to green back up and stayed short. This allowed me to aerate and top dress with organics, then seed with 5 different TTTF seeds. I let the fescue grow up to 2.5"-3"+ before mowing. Reseeding every year in the fall will be a must. When the spring comes, keep the fescue tall and it will shadow the centipede, not allowing it to green up until much later. By the time the centipede is ready to green up, the fescue will have a good root and be strong. The next thing you need to keep in mind, is to water and feed the yard for fescue and not centipede. Year after year, you will gain some ground. Again, in the fall, cut the grass shorter (maybe 2") and reseed with different fescue. I have found when it gets really hot, the fescue will start to go dormant and the centipede will strengthen up. The main issue I see is the growth rate. The fescue will grow much faster and 3 days after cutting, the grass doesn't look even. But after you cut it, it looks like carpet. Funny note: Every house in my neighborhood has centipede sod. Every year before the centipede has greened up, but the fescue is going strong, someone always walks by and ask why my grass isn't deal dead like theirs. I always play dump and I say, "Im not sure." and smile.

Unless you are seeding zoysia or bermuda grass, then EARLY FALL IS ALWAYS THE BEST TIME TO SEED. The next best time is mid fall. If you wait until late fall then you don't have a chance to fill in any thin spots where you didn't get enough grass seed the first time. Spring is the second worst time of year to seed with summer being the worst. Even winter can be an better than spring or summer under certain circumstances.

bump...I see you found and posted to the original Park's Seed review thread on the Rate & Review Vendors Forum

Eric, you asked 2 questions. 1. Can high soil temperatures essentially kill seeds so they won't germinate even when moved to preferred temperatues? 2. Should I just start a new batch? I read both questions and all the answers. Rodney answered the first for you. My query was a continuation of the discussion and an attempt to get further information to help you with your second question.