Is It Time to Sow? - When Should You Plant Native Seed?
The short answer? No. The heat of summer is better spent planning for a late fall seeding or in a patio chair with a cool beverage or BOTH! Buying seed now is cool but planting it now, not so much.
The OPN Seed rule of thumb: there's not really one rule, just different times to seed depending on the species. Fall planting or dormant seeding is best when soil temperatures are below 50 degrees (this is usually mid to late November depending on your location). Winter or frost seeding allows for the season's freeze/thaw cycles to assist in establishing good seed to soil contact. You can even seed into a little bit of snow! Both of these sowing times are preferred for plant species requiring a cold period or stratification in order to germinate. Spring or active season seeding runs from late March through mid-June.
But don't prairie plants like it hot? Generally, yes. But we're talking mature plants with established root systems. Seeds are a different story. Think of it this way: You're planning a lovely outdoor party in October. You buy the decorations and table settings in July. Would you decorate and set the tables in summer simply because you didn't want to wait till party time? Of course not! Those decorations and table settings would take a beating and certainly not be their best once party day rolled around.
Seeds are hearty, but these little packages of life will do best if not tormented by fickle midwest summer rain, drought, heat and wind. So give seed a chance. Plan. Purchase. Prep. Don't plant.