Answer first: use 2 cups of fish bone meal per 1.5 cubic feet of base soil, blended with kelp meal, alfalfa meal, blood meal, rock phosphate, dolomite lime, azomite, and worm castings, then cure the mix for 30 to 60 days before planting. Fish bone meal is the phosphorus and calcium engine of the recipe. It tests around 3-16-0 with 14 to 20 percent calcium, and it breaks down faster than steamed bone meal because it is ground finer.

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Prerequisites

  • One 1.5 cubic foot bag of organic base potting soil, peat or coco based, with no slow-release fertilizer prills
  • A tarp, a shovel, and a dust mask rated for fine organic dust
  • A warm space that stays above 60 F for curing
  • Time: 30 to 60 days of cure before the soil is ready

Amendment list per 1.5 cubic feet of base soil

  • 2 cups fish bone meal
  • 1 cup kelp meal
  • 1 cup alfalfa meal
  • 1/2 cup blood meal
  • 1/2 cup rock phosphate
  • 1/2 cup dolomite lime
  • 1/4 cup azomite
  • 2 tablespoons Epsom salt
  • 1 tablespoon humic acid powder
  • 4 to 6 cups worm castings

For a full 8-bag batch, multiply every number by 8. Drop the fish bone meal to 1 cup per bag if your base soil already lists bone meal or fish meal on the label.

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Mix steps

  1. Lay the tarp on a flat surface and put on the dust mask.
  2. Empty the base soil and the worm castings onto the tarp.
  3. Add the fish bone meal and turn the pile with the shovel until no clumps remain.
  4. Add the kelp meal, alfalfa meal, and blood meal, then turn the pile again.
  5. Add the rock phosphate, dolomite lime, azomite, Epsom salt, and humic acid, then turn until the color is the same throughout.
  6. Add water one quart at a time and turn until a handful squeezed in your fist holds its shape without dripping.
  7. Cover the pile with the tarp and cure it 30 to 60 days in a warm spot, turning it once a week.
  8. Move the cured soil into sealed bins and write the mix date on the lid.

How to use the finished soil

  1. Fill the bottom third of a 7 to 15 gallon pot with cured super soil.
  2. Fill the rest of the pot with plain base soil.
  3. Plant the clone or seedling into the plain top layer so roots start in mild soil.
  4. Water with plain water only, and stop if runoff turns dark brown, which means the mix is still hot.
  5. Top dress 1 cup of cured soil at the start of flower if lower leaves pale before week three.

Common mistakes

  • Planting seedlings straight into the amendment layer. Young roots burn in uncured mix.
  • Skipping the cure. Raw fish bone meal and blood meal release ammonia that damages roots.
  • Leaving fish bone meal on the surface of an outdoor bed. Raccoons, dogs, and rodents dig it up.
  • Doubling the phosphorus sources. Phosphorus builds up in soil, and too much ties up zinc and iron.
  • Reusing the mix with no re-amendment. Spent soil needs fresh castings and a half dose of fish bone meal.

Store leftover fish bone meal in a sealed bucket away from pets and out of the rain. The smell fades once the soil is cured and covered.

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