By Bill Kleiman, The Nature Conservancy
The photo above is from this season of a 2010 planting, our 97th at Nachusa Grasslands. There is a lot of gayfeather and white indigo. Harder to see are the thimbleweed, coreopsis, lupine, various sedges and grasses. It looks great but Cody and I thought it might turn out dull.
The well drained silt loam soils were planted with hay from 2000 to 2005, then converted back to corn until we planted the field to prairie in 2010.
We were concerned that the seeds and roots of the hay field were going to show up and swamp our prairie seeds. We discussed only planting seed from combined prairies. This would have been easy to obtain but lower diversity.
We ended up deciding to plant the full monty of hand harvested seed. We planted 134 species at 50 pounds per acre of bulk weight of seed. This weight includes chaff and stems.
This is in our Stonebarn Savanna unit. Here is a link to the planting summary we wrote back in 2010. It has the species lists, techniques used, map, soil map, etc.:
grassland restoration network 
The one thing that surprises me about the planting summary for prairie planting #97 is the special treatment for Asclepias tuberosa (butterfly milkweed). It is a gorgeous plant, but it grows so easy from seed I’m surprised it is given special treatment separate from the regular seed mix. Butterfly milkweed has popped up in most of the sunny areas of my garden. There are even some bonsaied in my lawn since my lawn does not receive any chemicals. I have not planted these plants. I just let them spread on their own from seed. The original source of the seed was one plant put in the garden by my home’s former owner.