The base recipe at a glance

Mix equal parts by volume of sphagnum peat moss or coco coir, aeration (perlite, pumice, or rice hulls), and finished compost or worm castings. That 1:1:1 base holds water, drains fast, and feeds a plant through the first three to four weeks of vegetative growth. Add mineral powders and meals only after the base is blended, so they disperse evenly instead of settling in pockets.

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One cubic foot of finished mix fills roughly a 7.5 gallon pot. Scale the recipe by the number of pots you plan to fill, not by the size of your mixing tarp.

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Before you start

  • A tarp, wheelbarrow, or kiddie pool for mixing
  • A dust mask and gloves for peat, perlite, and rock dust
  • A one-gallon bucket and a half-cup measure for amendments
  • Compost that has finished heating and smells earthy, never sour

How to mix the base

  1. Pour the peat moss or coco coir onto the tarp and break up any clumps by hand.
  2. Add the aeration component on top of the peat.
  3. Add the compost or worm castings as the final layer.
  4. Turn the pile with a shovel from the outside edge toward the center.
  5. Keep turning until the color is uniform and no single ingredient shows in streaks.
  6. Add water in small amounts while turning until the mix holds together when squeezed but releases no free drops.

Amendments per cubic foot of base mix

  • 1 cup kelp meal for potassium and trace elements
  • 1/2 cup crab or shrimp meal for slow-release nitrogen and chitin
  • 1/2 cup neem meal or alfalfa meal for nitrogen and pest suppression
  • 1 cup rock dust or glacial rock powder for broad trace minerals
  • 1/2 cup gypsum for calcium and sulfur without shifting pH
  • 1/2 cup oyster shell flour for steady calcium release
  • 1/2 cup dolomite lime if you used peat, since peat runs acidic

Skip the dolomite if you built the mix on coco coir. Coco coir arrives near neutral and extra lime can push pH too high.

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Let the mix rest before planting

Meals and rock powders need microbial activity to become plant-available. Fill your containers, water the mix to the squeeze-test moisture level, and cover them with a tarp or lid. Let the blend sit for two to four weeks in a warm spot, turning it once a week if you keep it in a pile instead of pots. The mix is ready when it smells like forest floor and no ammonia odor remains.

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Watering and pH notes

Water when the top inch of soil feels dry at knuckle depth. Organic soil blends buffer pH on their own, so aim for a water pH between 6.0 and 6.8 and stop chasing decimal points. Feed plain water for the first month. After that, top-dress with worm castings or a compost tea every two to three weeks through flower.

Fixes for common problems

Mix stays soggy for days

Add one extra part perlite or pumice and remix. Heavy compost and fine peat are the usual culprits.

Leaves yellow in early veg

The compost was likely immature and is tying up nitrogen. Top-dress with a half inch of fresh worm castings and water it in.

Tips burn and curl

You over-amended. Cut the mix with plain base at a 1:1 ratio and replant into the diluted batch.

Fungus gnats appear

Let the top two inches dry between waterings and keep a layer of coarse sand or rice hulls on the surface.