Echinacea Seeding

I intend to plant about an acre and a half of Echinacea purpurea. Could you advise me as to how much seed I will need for this purpose as well as planting info. Does it need to be started in a greenhouse and transpanted or can it be planted directly.

Echinacea is direct seeded at the rate of 13.5 kilogram per hectare or eight kilogram per 1.5 acres.
If you seed them into a seedbed first and then transplant, you will need 0.7 to 1 kilogram per hectare or 280 to 400 grams per acre (420-600 grams per 1.5 qcres)