What Is Super Soil for Cannabis?
Super soil is a nutrient-rich organic mix that feeds a cannabis plant from seedling to harvest with plain water instead of bottled nutrients. You build it from a base of peat or coco, compost, and aeration, then blend in dry organic amendments and let the pile cure for 30 to 60 days before planting.
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The strongest part of the blend, the amended super soil, goes in the bottom of the pot and a mild mix goes on top, so young roots never touch the hottest material. The plant grows down into the food as it needs it.
best super soil recipe for autoflowers
How Do You Make Super Soil at Home?
The whole job takes five steps. Set aside an afternoon for mixing and a month or two for the cure.
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- Build the base. Blend one part peat moss or coco coir, one part compost or worm castings, and one part perlite or pumice by volume. A 10-gallon batch uses about 3.3 gallons of each.
- Mix in amendments. Add the dry nutrients below one cup at a time and stir until the color is even.
- Moisten the pile. Add water until the mix clumps when you squeeze it but no drops fall. Dry mix will not cure.
- Cook the batch. Store it in a tote with the lid loose, in a warm spot away from direct sun. Turn it once a week.
- Layer the pots. Fill the bottom third with super soil, the middle with a 50/50 blend, and the top third with plain potting mix.
Super Soil Recipe: Base Mix and Amendments
The base ratio stays 1:1:1 by volume. The amendment list below is measured per cubic foot of finished base mix, which fills about 7.5 gallons of pot space.
- 1/2 cup blood meal for fast nitrogen
- 1/2 cup bone meal for phosphorus and calcium
- 1/2 cup fish bone meal or bat guano for slow phosphorus
- 1/4 cup alfalfa meal for nitrogen and natural growth compounds
- 1/4 cup kelp meal for potassium and trace minerals
- 1/2 cup rock phosphate for long-release phosphorus
- 1/2 cup greensand or glacial rock dust for potassium and minerals
- 1/4 cup dolomite lime to buffer pH and add calcium and magnesium
- 1/4 cup gypsum for calcium and sulfur
- 2 cups worm castings for microbial life
A 10-gallon pile of base mix is 1.3 cubic feet, so multiply each amount by 1.3. Rounding up by a spoonful does no harm.
Do You Have to Cook Super Soil Before Using It?
Yes. Fresh amendments are raw and can burn roots. The cure gives bacteria and fungi time to break those materials into forms the plant can absorb.
Plan on 30 days at the short end and 60 days for a better result. The pile heats up as microbes multiply, then cools. It is ready when the temperature returns to room level and the mix smells like a forest floor.
Cold weather slows the cure. A winter garage can stretch it to 90 days. Move the tote inside if you want it done sooner.
Which Compost Works Best?
Use compost you trust. Worm castings, leaf mold, and finished backyard compost all work. Manure compost should age for at least six months so salts and pathogens settle out.
Cheap municipal compost can carry herbicides that kill cannabis. If you cannot trace the source, make your own or buy from a grow shop.
Compost does two jobs. It feeds microbes and it holds water and nutrients in the root zone.
How Much Super Soil Does One Plant Need?
Pot size drives yield more than amendment choice. Super soil needs volume because the plant eats from the mix for months.
- 3-gallon pot: small autoflower or a short veg cycle
- 7-gallon pot: standard choice for one photoperiod plant
- 10 to 15 gallons: large plants and long veg times
Fill the container to within an inch of the rim so roots have room to spread.
How Do You Water and Feed a Super Soil Grow?
Water with plain water adjusted to pH 6.0 to 7.0. Add nothing else unless the plant shows a clear deficiency.
Water in stages until a little runs out the bottom, then wait for the top inch of soil to dry before the next round. Wet soil with no air gap drowns the microbes that do the feeding.
If growth stalls at the start of flower, top-dress with half a cup of worm castings and water it in. That covers most mid-grow cravings.
Can You Make Super Soil Without Animal Products?
Yes. Swap blood meal for soybean meal, bone meal for extra rock phosphate and gypsum, and fish bone meal for more rock phosphate. Kelp meal, alfalfa meal, and compost carry the rest.
Vegan mixes break down slower, so give them the full 60 days to cure.
What Mistakes Should You Avoid?
- Planting a seedling straight into hot super soil. It will burn.
- Skipping the cure and using the mix right after mixing.
- Letting the curing pile dry out. Check moisture once a week.
- Adding synthetic nutrients, which shut down the microbial system you built.
- Reusing spent mix without new amendments and fresh castings.
Is Super Soil Cheaper Than Bottled Nutrients?
Not on the first batch. A full set of organic amendments can run $60 to $100. The bags last several grows, so the cost per plant drops with each cycle.
Bottled nutrient lines cost less up front but get replaced every grow. Super soil also removes most of the measuring and mixing from your routine.
Do You Still Need to Check pH?
Yes. Dolomite lime buffers the mix toward the 6.0 to 7.0 range that cannabis prefers, but tap water and compost can push it off course. Test the runoff every few weeks with a basic meter.
Off pH locks out nutrients even when the mix is rich. A $20 meter saves a crop.
How Should You Store Leftover Super Soil?
Keep it in a lidded tote out of the sun. A dry pile goes dormant, so add a splash of water every few weeks if you plan to store it for months.
Cooked super soil keeps for about a year. After that, microbial activity drops and you should re-amend before use.