Answer: As you've recently experienced, getting turfgrass established on a steep slope can be a hit or miss proposition. The soil needs to be loose enough for good root penetration, but not so soft that it runs off during a rainstorm. Since you've tried seeding twice, I think sodding would solve the problem. I'd rake, till or dig the soil to make it more hospitable to root growth then lay sod over the soil. Sod will already have a healthy network of roots so your goal will be to make sure the sod makes really good contact with the soil so the roots can work their way down into the soil. It should only take a few weeks after installation for the sod to extend its roots into your soil. The thick sod and thick network of roots should stop the soil erosion.
Best wishes with your lawn!
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