Mow low; quite low, in fact. If you want the wildflowers, you won't be able to mow except yearly (fall).

I found The "Tallgrass Restoration Handbook" by
Cornelia F. Mutel and Stephen Packard to be the best source.

Here is a link that might be useful: Garden Musings Blog

How old is the planting and what is the reason for the mowing. If its relatively new planting, less than 4yrs old, then one can assume the mowing is for weed control. If you are mowing for weedcontrol, then the timing of the mow is critical. If you are mowing for weed control, typically you will mow 3 times, with 21 day intervals inbetween the mowings, with the first mowing taking place when the weeds you are mowing are just starting thier seed heads. You can mow high if it is for weed control.

I have a 5 acre restoration in progress.(4 years old) Most of it I dont need to mow anymore, but I still have about 1 acre thats a problem for me. I burned this year, but I burned too early. Thats a problem also.