If you’re contemplating putting in a native seed flower bed in late fall, August is a good time to get the soil ready.
Your main job is to get rid of all the grass and weeds and have a clean area without any vegetation.
Don’t till as that will bring up weed seeds.

I’d loosen up the top 1/2″ of soil and keep the area moist to encourage any weed seeds to germinate now before the growing season.
In St. Louis, Scott Woodbury our resident expert, suggests advice from Merv Wallace…
“Merv recommends one ounce of seed mix per 400-500 square feet and 3 grams per 20 square feet.
With your 4 grams, you are looking at around 25 sq ft.”
Sow the seeds on the surface in December.
I’d suggest mixing the seed with either play sand or potting mix. It makes for better disbursement when you throw the seeds out.
Don’t mix into the soil or cover with straw.
Just let the seeds sit on the surface.
Winter frost heave will move the seeds into the upper layer of the soil to the perfect depth.
Seeds will sprout in early April.
Native plants don’t need fertilizer, but might need watering during the first year.
Note – I like to cover my seeds with a light dusting of potting mix to hide them from the birds.