I'm not sure what 'black cow' is
OK. Enough people have asked, so here is a recipe. Your mileage may vary.
30-50% good quality potting soil (not pre-ferted)
30-50% perlite
10-20% worm castings
10% compost
Per gallon of soil mix:
1 tablespoon each: blood meal, bone meal
2-3 tablespoons: kelp meal
2-4 tablespoons rock phosphate (grind to powder if possible)
And there ya go.
And remember that a little less is better than a little more. It's pretty hard to get organic ferts out of your soil if you over-do it, and you can always supplement with fish emulsion, blood meal tea, or guano if they need extra later.
If you have to leave anything out, the rock phosphate would be the first thing to drop. The most important nutrient to be careful not to overdo is blood meal; the one you can best get away with overdoing is kelp.
O