Lawn in this case. 2 and 3 years ago we had 90F heat until mid-September, and the grass germination season got compressed. Last year was much better, being able to get started earlier goes a long way toward root establishment before winter. No doubt the warm fall last year helped too. Here I can usually get decent results if I'm done seeding by Oct. 8th or so. Later than that germination can take too long, the cool snaps slow things down, and even the low sun angle by the end of October starts to be a factor. I'm talking about seeding on dirt, not overseeding - we've got a lot of dirt areas due to summertime projects. I'm chomping at the bit, lol.