Quick answer

Super soil is an amended potting mix that feeds a plant for a full cycle with water only. Mix base soil with meals, rock dust, and minerals. Add water until a squeezed handful holds shape, then let the pile sit 30 to 60 days. Use the mix in the bottom third of the pot and fill the top with plain soil.

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What you need

The recipe below makes about 12 cubic feet, or 90 gallons. That fills six 15-gallon pots.

Organic Cannabis Super Soil Recipe: A Water-Only Mix That Works

  • 8 bags base potting soil, 1.5 cubic feet each
  • 1 bag earthworm castings, 1 cubic foot
  • 5 lb blood meal
  • 5 lb bone meal
  • 5 lb bat guano
  • 5 lb fish meal
  • 2.5 lb alfalfa meal
  • 2.5 lb kelp meal
  • 1 cup dolomite lime
  • 2 cups azomite or rock dust
  • 1/2 cup Epsom salt
  • 2 tbsp humic acid
  • 1 tbsp mycorrhizal fungi, added at potting time

Step by step

  1. Lay a tarp on flat ground. Dump the 8 bags of base soil into one pile.
  2. Add the earthworm castings. Turn the pile with a shovel until the color is uniform.
  3. Add the blood meal, bone meal, fish meal, bat guano, alfalfa meal, and kelp meal. Add one amendment at a time and mix before the next. Meals clump, and clumps stay hot.
  4. Sprinkle the dolomite lime, azomite, Epsom salt, and humic acid over the pile. Turn it again.
  5. Add water from a hose or watering can. Target a handful that holds shape and drips one or two drops. Wet spots and dry spots both stall the cook.
  6. Cover the pile with the tarp. Keep it out of rain and direct sun.
  7. Turn the pile every 7 to 14 days. Add water if the center feels dry.
  8. Wait 30 days at minimum, 60 days for a softer mix. It is ready when it smells like forest floor and no ammonia.
  9. Store the finished mix in bins or bags with the lid loose. It keeps for about a year.

How to use it in pots

Fill the bottom 30 to 50 percent of the pot with super soil. Fill the rest with plain base soil. Plant the clone or seedling in the plain layer. Roots reach the amended layer in 2 to 3 weeks.

Best Super Soil Recipe for Cannabis: Comparison Review

Use a 10-gallon pot or larger. A 7-gallon pot works for short plants. Small pots run out of root space before the mix runs out of nutrients.

cannabis super soil mix guide

Watering

Water when the top 2 inches of soil are dry. Super soil holds moisture, so pots need less water than plain mix. Use plain water at pH 6.2 to 6.8. Hold off on bottled nutrients for the first 4 to 6 weeks. Some plants show leaf tip burn in week 3. Watch and wait.

Common mistakes

  • Planting into pure super soil. Roots burn in the meal-heavy layer.
  • Using the mix before it cooks. Raw blood meal and guano release ammonia.
  • Letting the pile dry out. Microbes stop and the cook stalls.
  • Skipping the rock dust. Azomite adds trace elements that meals do not supply.
  • Mixing mycorrhizal fungi into a hot cook. The heat and ammonia kill spores. Add it to the planting hole instead.

Sourcing and law

Buy amendments listed by OMRI if you want inputs allowed in certified organic production. Check your state rules for hemp and cannabis before you plant. Federal law treats hemp and cannabis under different rules.