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
1.5-2 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.
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