Don’t argue with Mother Nature.
Plant Wildflower Seeds in fall.
OK, most people plant them in spring, and that’s fine. But think about it. In the wild, when wildflowers “go to seed” after the flowers fade, that’s when the seed is dropped. It simply falls to the ground and waits for the cycle through winter to spring. So the naturally-planted seed is planted in fall, not in spring.
Earlier bloom in spring. Here’s another big advantage in fall planting. Your wildflowers will be in bloom several weeks earlier than spring-planted seed! And isn’t that what you want?
So now’s the time. It’s best to wait until killing frost, then clear the ground of grasses and weeds, just like you would in spring. Use a shovel or rake for a small patch, or a rototiller for a bigger planting, and just spread the seed. It’ll be just fine through the winter, and be up and growing for you in very early spring.
What about the annuals? If you’re planting a wildflower mixture with annuals, even all annuals, fall planting is still best. The annual seed comes right through the winter like perennial seed does. (There are some exceptions. Cosmos, for example, are native to desert-like areas, and may be killed by a late frost in spring.) But red poppies, plains coreopsis, cornflowers, black-eyed susans, plus all the perennials will come right through the winter for you and be in good growth before you can get out there to plant in spring.
Plant now! Don’t argue with Mother Nature!