Hello Sam,

Late August through September is the best time to overseed lawns in Michigan. https://www.canr.msu.edu/news/tips_for_seeding_lawns_in_september#:~:text=September%20is%20the%20ideal%20time,drying%20all%20facilitate%20turf%20establishment. Grass seed needs to germinate, establish stems and leaves and develop a root system in order to store sugars for winter survival. Since many of the useful cultivars of turf grass can take 2-3 weeks to germinate, we need upwards of 2 months of favorable weather to ensure that the new grass plants are mature enough to survive.

Starting grass seed in October is more hit-or-miss. Depending on the weather this year, the young grass plants may become established before the weather gets too cold or the seed my germinate and then the young grass plants get too cold before they are mature enough and they die in the cold weather. https://www.canr.msu.edu/news/late_season_lawn_seeding If your area is small and the financial burden of “wasted” seed is not a concern, you can go ahead and try.

Another option is dormant seeding. In this scenario, you apply the seed when the temperatures are below the germination temperatures (typically November) and the seeds will stay dormant in the soil until the temperature is correct for grass seed germination next spring. The potential problem is if we have heavy snow cover and a damp spring, the grass seed may rot before germination can take place.

If you decide to wait until spring to overseed, here is an article that addresses spring overseeding: https://www.canr.msu.edu/news/tips_for_reseeding_lawns_in_the_spring