How to Make Your Own Super Soil Like a True Master Grower

It's what plants crave!

Marijuana seedling sprouts in soil Source: iStock

Whether you’re a seasoned grower or just dipping your toes into the cultivation scene, you’ll want to make sure your cannabis plants grow up to be robust and healthy.

Some new growers may be under the impression that all their plants need to grow are water and sunlight. In reality, cannabis plants require 17 essential nutrients to reach their full potential. Super soil can help. 

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This type of nutrient-rich soil preparation nourishes plants without the need for adding chemical fertilizers throughout the growth cycle. In this post, we’ll show you how to make super soil and take you through the many benefits it offers.

What is Super Soil?

Super soil is a chemical-free soil preparation that is specifically formulated to provide the nutrients the cannabis plant needs throughout its entire growth cycle. This type of soil is intended to be 100% organic, making it the ideal enriched planting medium for organic growers.

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The process of creating super soil facilitates an ecosystem in which microorganisms can thrive and nourish the plant without the need for chemical fertilizers. 

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Subcool of TGA Genetics is credited with developing the super soil used by many growers today. In 2009, he shared his original super soil recipe with High Times, and growers have continued to experiment and adjust their own recipes to produce the best possible results.

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Benefits of Super Soil

Why use super soil? Super soil is more labor-intensive than purchasing pre-mixed fertilizer solutions and can cost more initially. In addition to the heavy lifting, this method requires patience, as super soil needs to rest for a minimum of 30 days before it’s ready to be used. For most growers, however, the benefits tend to exceed the drawbacks.

Typically, nutrients need to be added to cannabis plants in various ratios throughout the growth cycle.

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When planted in super soil, on the other hand, cannabis plants can grow strong and healthy with only the help of plain water. Super soil is designed to be biologically balanced and, when used properly, it can alleviate worries of over-fertilizing and causing fertilizer burn. 

Although chemical fertilizers can be effective, they also contribute to soil degradation and the loss of organic carbon in the substrate. Organic growing methods are becoming increasingly popular among home growers and the commercial market.

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Many believe that organic cannabis offers a better terpene profile and thus a better taste and aroma. Super soil requires no harsh chemicals, so there is no chemical runoff from your plants. Using this soil preparation can thus be more sustainable and environmentally friendly.

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How to Make Super Soil

If you’re growing your cannabis outdoors, you may plan to use the existing soil in your garden as your base soil. If this is the case, pick up a soil testing kit at your local garden center.

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These are relatively inexpensive and can tell you what ratio of plant macronutrients is already present in your soil. Make sure that your garden soil has not previously been treated with chemical pesticides or fertilizers. If it has, consider buying organic substrate from the store instead. 

This recipe is based on Subcool’s original super soil recipe. Growers have made a number of tweaks and substitutions to this formula, so feel free to use it as a guide and make it your own.

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Super Soil Recipe

Equipment:

  • Garden shovel or pitchfork
  • Tarp, large plastic tub, or wading pool (a.k.a. kiddie pool)
  • 3-5 large garbage bins with lids

Ingredients:

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  • Base Soil: 6-8 large bags of organic soil containing coco fiber and mycorrhizae (Subcool recommended Roots Organic)—or equivalent amount of garden soil. 
  • 25-50 lbs organic worm castings
  • 5 lbs steamed bone meal*
  • 5 lbs Bloom Bat Guano**
  • 5 lbs blood meal*
  • 3 lbs rock phosphate
  • ¾ cup Epsom salt
  • ½ cup dolomite(sweet lime)
  • ½ cup azomite 
  • 2 T powdered humic acid
  • Water

*Many organic growers take issue with the use of animal byproducts, either for ethical reasons or because the animals in question may not have been raised using organic methods, which effectively renders the soil non-organic. 

**There are also a few concerns with the use of bat guano. It may not be sustainably harvested, and bats are often the prime suspects regarding the transfer of zoonotic diseases. You may choose not to use these ingredients and opt for additional worm castings, supplemented with alfalfa meal.

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Super Soil Preparation Instructions

  1. Pour half of the base soil onto the tarp. If you’re using a kiddie pool or smaller container, you may have to do this in multiple batches. 
  2. Add the other ingredients(also known as amendments) to the pile except for the water. If you’re mixing in two batches, add only half the quantity of the amendments at this time and save the other half for your next batch)
  3. Top with the remaining soil.
  4. Use your shovel or pitchfork to thoroughly mix the base soil with the amendments. Take care to break up any large clumps in the soil throughout this process as well.
  5. Transfer your mixed super soil to the garbage cans and add about 3 gallons of water per bin(enough to moisten, but not completely saturate). This helps distribute the nutrients. 
  6. Mix up the soil inside the bins to spread the water throughout.
  7. Store the soil in a warm location for a minimum of 30 days or up to six months (some growers recommend 6-12 weeks). This allows the microorganisms time to establish and enrich the super soil.

How to Use Super Soil

After your super soil has been allowed to sit for several weeks, it’s ready to use. Do not plant your cannabis plants directly in super soil. It is highly nutrient-rich and could cause fertilizer burns if applied directly.

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If you’re growing potted plants, fill the bottom ¼ or ⅓ of your pots with super soil. On top of this, create a “buffer zone” by adding a 2-inch layer containing a 50/50 mix of plain, organic base soil and your prepared super soil.

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Fill the rest of the pot with base soil only and add your plant to this zone. The cannabis plant’s roots will eventually reach down to the super soil layer and extract the nutrients. 

We’d like to thank the late, great cannabis breeder Subcool for his super soil recipe and his many contributions to the cannabis industry as a whole.

How to Make Your Own Super Soil Like a True Master Grower was last modified: by