Should I plant wildflower seeds prior to winter or in the spring?

Question: I have a wildflower meadow and would like to plant more flowers. I have harvested quite a bit of Black-eyed Susan seed, as well as Mexican Hat and Coneflower seed from the meadow this summer. When should I plant the seed…prior to winter or in the spring? I have looked online and found both read more Should I plant wildflower seeds prior to winter or in the spring?