g-man said:
The climate prediction center forecasted a warmer September and winter. ... Get your seed down ASAP
Just wanted to mention that temperature/weather is only one aspect of the issue. There's another aspect which even a warm fall won't help, and that's sunlight.
We often talk of putting fertilizer on our lawn to "feed' it, but the real food for grass is sunlight. The energy used by plants is almost entirely from photosynthesis, which requires sunlight to generate carbohydrates. The fertilizer just provides the raw materials that are used to build more / larger plant cells, but the energy to do that all comes from the sun.
The chart below comes from the field of solar energy generation, but shows "average peak sun hours" by month for Concord, NH, which is not only near me, but about the same latitude as most of the population of Ontario.
The takeaway from the chart for new grass establishment is that even if the weather remains warm, grass that germinates in late September gets about 3.5 "peak sun hours" per day, while grass that germinated in mid-August saw about 5 peak sun hours per day. So, even if the weather remains warm enough for the grass to keep growing, there's a lot less energy available for the baby grass plants to grow.
Another thing to note from the chart is that there's less energy in October sunlight than there was in March. Nobody would dream of growing grass in Ontario in March, but there's more sunlight to do so at that time than in October! Even September just barely exceeds March in terms of energy in the sunlight.
The latest I've successfully seeded KBG here in NH was September 9th, and that was extremely thin before winter, and didn't grow enough to need cutting until May 9th the following year.
I've successfully seeded PRG here in NH as late as Oct 11th due to septic tank repairs. Only about half of it germinated and got tall enough to survive the winter, but enough of it did to hold the soil in place through the winter.
That said, you've got nothing to lose by trying to seed now -- the worst that can happen is it fails completely, and you'll have to do spring seeding anyway, but that's no worse off than if you do nothing now. However, at this time of year, every day starts to matter a lot.
