Ephemeral seed should be sown as soon as possible after maturing and collecting. First I use clean pots and sterile potting medium. I happen to prefer Scott's Serria Perennial Mix. Any good peat-perlite mix will do. Pots are filled to slightly below the lip with medium and gently pressed to settle and level the surface.
Seed is then surface sown.
Do not use calcium grit as it will dissolve in a mess and change the pH of your mix. Grit is available at feed and farm supply stores in 60 pound bags. The trays are allowed to drain and then placed in an open cold frame protected from varmints. A shady spot is best. Keep the pots moist, but not wet, during summer and fall.