If it has already been disked up well enough that the grass is gone then I would go ahead and drag and plant. It's difficult to answer your question not being able to see the plot, but being in Wisconsin I would say that your planting time may be running short.

I've planted clover plots in suspect conditions in the past and they have done well if they get enough moisture after planting. If grass comes up in it in the spring you can hit it with some herbicide.