Super soil is a water-only organic blend made by charging a base potting mix with meals, rock dusts, and mineral amendments, then letting it "cook" for 30 to 60 days while microbes break those inputs into plant-available nutrients. A standard cannabis super soil recipe uses roughly 1 to 2 cups of total amendment per cubic foot of base mix. Mix it, moisten it, cure it, and most photoperiod plants finish a full cycle on plain water.
How to Amend Super Soil for Cannabis: Rates, Steps, and Timing
What goes into a cannabis super soil recipe?
A complete mix has four parts: a base soil, a compost or casting source, aeration, and a mineral and meal amendment package. The base and compost feed the microbial herd, aeration keeps roots breathing, and the amendments supply slow-release nitrogen, phosphorus, potassium, calcium, and trace minerals. Nothing in the mix is a soluble salt fertilizer, so the plant eats what the soil biology releases.
super soil vs living soil for cannabis
Cannabis super soil recipe (per cubic foot)
Base mix
- 2 parts high-quality organic potting soil (about 2/3 cubic foot)
- 1 part earthworm castings or finished compost (about 1/3 cubic foot)
- 1 to 2 cups perlite or pumice for drainage
Amendment package
- 1/2 cup blood meal
- 1 cup bone meal
- 1/2 cup bat guano (0-5-0 or 0-7-0)
- 1/2 cup kelp meal
- 1/2 cup alfalfa meal
- 1 cup greensand
- 1/2 cup rock phosphate
- 1/2 cup dolomite lime
- 2 tablespoons azomite or glacial rock dust
- 1 tablespoon Epsom salt
- 1 tablespoon humic acid powder
- 1 tablespoon mycorrhizae, added at planting, not during cooking
How do you mix and cook super soil?
- Spread the base mix on a tarp and dump the amendments on top.
- Turn the pile at least three times until the color is uniform and no clumps of meal remain.
- Add water while turning until the mix holds together when squeezed but does not drip.
- Store it in a bin or covered pile at 60 to 80 degrees Fahrenheit, out of direct sun.
- Stir every one to two weeks and re-moisten if the surface dries out.
How long does super soil need to cook?
Four to eight weeks is the practical window, with 30 days as the bare minimum and 60 days as the safer target. During that time the pile will warm slightly and may grow a white fungal fuzz on the surface, which is a sign of active decomposition rather than spoilage. Soil that still smells like ammonia or blood meal after a month needs more turning and more time.
cannabis super soil mix ingredients
How do you layer super soil in a pot?
Fill the bottom third of the container with straight super soil, the middle third with a 50/50 blend of super soil and plain base mix, and the top third with plain base mix. That gradient lets young roots grow into mild soil first and reach the hot layer once the plant is hungry. Never plant a seed or clone directly into the bottom layer.
Can you use super soil for autoflowers and seedlings?
Seedlings and clones should start in plain potting mix and be transplanted once roots fill the starter pot. Autoflowers have a short veg window and often burn in full-strength super soil, so use a half-strength batch or keep them in the top layer and top-dress lightly. Photoperiod plants in 7-gallon or larger pots handle the full recipe best.
Common super soil mistakes
- Planting before the cook finishes, which burns roots with raw amendments.
- Doubling the blood meal for faster growth, which spikes nitrogen and locks out calcium.
- Skipping perlite, which turns the mix into a soggy, oxygen-poor brick.
- Reusing the soil without re-amending, since the plant consumes the available nutrients.
- Overwatering a water-only mix, which drowns the microbes doing the feeding.
Do you still need nutrients with super soil?
Most plants in 7 gallons or more of properly cooked super soil need nothing but water through veg and the first half of flower. Around week 5 or 6 of flower, a top dressing of worm castings, kelp meal, and a phosphorus source keeps the mix working through ripening. Keep water pH between 6.2 and 6.8 so the mineral amendments stay available.