I've never had success with cold stratification in the fridge. The seed was fresh from a native plant nursery, so I trust its good. Because we're trying to expand our prairie patches, we just throw the seed over an area and hope for the best. One variety I could not get to germinate after putting in the fridge, did eventually germinate outside.
If anything, be patient with native seeds. I had winter sowed some Swamp Milkweed and nothing came up the following year, but it did the year after that.
Same is true with the seed mixes, some plants came up right away, but others took two years and I suspect (hope) more will come later. The Echinacea Purpurea in that seed mix (our first planting) took two years. The first native patch, the soil was about as bad as you can get. The seed mix was specifically for clay subsoil, such as we had after construction. There are some weeds in that patch, but there is also a grand showing of the natives.
If this is a plant you really want and you have the means to do so, find a native nursery local to you and get some dormant roots or plugs. I will do seeds out in our wild areas, but I have less patience for them around the yard. I want to know what is weed and what is not.
