Another consideration in reference to Elmar’s comment would be do you intend on terminating your cover crop before it goes to viable seed? Depending on your desired outcomes that can change a lot in the arena of adapted seed. I’ve been working on a perennial system so we can let out cover crops go to seed and become more adapted to the site specifically, as well as save money on buying cover seed annually. I have red clover growing from inoculant-coated seed where a PhD from our local Ag Extension told me it was unlikely if not impossible to get established. Germination was poor at first but the surviving members grew to maturity, went to seed, and their progeny are slowly becoming more readily viable in conditions with a variety of limiting factors. We don’t have a lush stand of clover, but it’s presence is notable and its diversity appreciated!