The period from mid-August to early September is probably the best time of the year to seed grass in southern Minnesota. Here are a few tips to improve your results.
1) Eliminate all perennial weeds in the planting area before working the soil to create a good seed bed. We have found that spraying a mix of Roundup and Weed-B-Gone at least two weeks ahead of planting to be the most efficient and effective method.
2) Create a nice seed bed by hoeing, cultivating, tilling and raking so crumbly soil can mix with the seed.
3) Apply grass seed generously, AND lightly rake the seed into the top 1/2 inch of soil. Do not leave grass seed lying on the soil surface. The seed germinates much better and more quickly when mixed with the soil. Avoid mixing the seed in too deeply. Mixed into the top 1/2 inch of soil is perfect. Use a spring tine leaf rake and be sure to rake it both directions.
The picture shows the worked area with grass seed on top of the soil surface and what it looks like when the rake goes over it.
4) Keep the area moist with morning and afternoon watering for 7-10 days and you will have great grass!
5) Use / install erosion control fabric on slopes.