I've had good luck with lily-of-the-valley, creeping vinca ground cover, and the perennial geranium (cranesbill) in my shady clay corner here in Ohio. When I tried astilbe and lady's mantle they didn't last long. In order to get one fern to grow I had to completely change out the soil in that spot. Also, my perennial geranium grows anywhere and is a real life saver for bare spots in sun or shade. I don't know what variety mine is because a friend of mine just yanked it out of his flowerbed and handed it to me, but it's great.
I've had good luck with lily-of-the-valley, creeping vinca ground cover, and the perennial geranium (cranesbill) in my shady clay corner here in Ohio. When I tried astilbe and lady's mantle they didn't last long. In order to get one fern to grow I had to completely change out the soil in that spot. Also, my perennial geranium grows anywhere and is a real life saver for bare spots in sun or shade. I don't know what variety mine is because a friend of mine just yanked it out of his flowerbed and handed it to me, but it's great.