Select low-growing grasses if you want the wildflowers to be prominent in the prairie. Recommended low-growing grasses include little bluestem, sideoats grama, and prairie dropseed. Low-growing grasses are best for urban landscapes. Such a planting will provide seeds for wildlife in fall, and protective cover from winter through spring. Tall-growing grasses include big bluestem, indiangrass and switchgrass.
Many different wildflowers do well in Wisconsin.
Another source of information is the Wild Ones organization. You may wish to link up with them. Two good references can help you become more knowledgeable about prairies and prairie gardens. The Prairie Primer , a very attractive 59-page spiral bound book that is packed with information with a real focus on Wisconsin prairies. Line drawings and good plant information as well as excellent how-to planting information for small scale prairie plantings make this a very useful reference for the gardener and a great starting reference on the subject for the interested professional.