If you are using a cool season grass then I would wait until the soil temps reach 55*. That is optimal germination temps for cool season grasses.I live in Kokomo, IN and missed the grass seed planting window last fall. I was told I could dormant seed anytime before spring. However, the winter weather prevented me from aerating and over seeding. The temperature in now starting to warm up and I want to know when is the soil dry enough to aerator and overseed. How is it determined? Is there a minimum required soil temperature?
Thanks for helping!
The soil doesn't have to be dry to aerate. You would actually get better results if you do it the day after a good rain. That way you get good penetration into the soil, just don't do it if you have standing water in the lawn.
The falacy is that you need to seed in the fall. This is only a recommendation as you get proper temperatures and ample moisture to aid in germination.
I've had good luck seeding at any point of the growing season, just as long as you are willing to keep it watered sufficiently to get the grass established.