How to make super soil for growing cannabis

You may know that organic soil is optimal for growing cannabis, but do you know about the benefits of super soil? This type of potting soil is not only organic but it also infuses your plants with a wealth of nutrients that ordinary soils may not offer.

Here you'll learn exactly what makes soil super and why you should consider using it as a cannabis cultivator. You'll also learn step-by-step exactly how to grow weed with super soil.

What is a super soil?

In the wild, cannabis plants grow freely like weeds. In a controlled environment, cannabis growth is altered and sometimes diminished depending on the quality of the soil used and any inorganic materials it may contain. But with super soil, you can mimic a wild environment to make your cannabis plants more fertile. Think of super soil as the closest possible growing medium to Mother Nature. Super soil is sometimes referred to as living soil because of how it recreates a natural growth environment for marijuana. This means less work for you as a cultivator, along with the potential for a larger yield of cannabis.

cannabis seedling
Soil is a substrate designed to infuse plants with every essential nutrient they will need throughout their life cycle.
Photo by: Gina Coleman/Weedmaps

Soil is a substrate designed to infuse plants with every essential nutrient they will need throughout their life cycle. An ecosystem of live microorganisms not only contributes to the plant's health but also to the planet's well-being. When you plant cannabis with the right type of soil, you can be sure there are no harmful chemicals or anything else entering the plant or the environment.

Planting with this type of soil is a win-win situation for the environmentalist and the cannabis growing enthusiast alike.

Why should I use super soil for growing cannabis?

There are many benefits to using super soil to grow marijuana. Here are a few of the top reasons why this soil could kickstart your cultivation:

  • Versatility: Whether you're growing indoors or outdoors, super soil can be an important item in your toolbox. This growing medium is versatile enough for you to use in virtually any environment.
  • All-Natural Ingredients: Super soil, containing only organic ingredients, is as close to nature's soil as you can get. The essential nutrients of nitrogen, phosphorus, and potassium work together to help cannabis thrive.
  • Aesthetics: If pleasing taste, fragrance, and smoothness are important to you, then super soil will not disappoint. Compared to other types of soil and growing methods, this process can enhance the flavor and scent of marijuana while producing silky smooth buds.
  • No Need to Flush: An absence of chemical salts means that there's no need to flush the plants before it's time to harvest, saving you time and effort, not to mention the vital resource of water.
  • Ease: Composting lays the groundwork for a streamlined process that may be easier than using other kinds of growing mediums. With nutrient-rich soil as your ally, you don't need to waste time worrying about maintaining pH and nutrients. All you need to do is provide the right water source and look forward to a quality harvest.

Disadvantages of super soil

Before you decide if super soils are right for your cannabis plants, it's a good idea to be aware of any potential drawbacks. Here are some disadvantages of growing with super soil:

  • Expensive: Super soil is not for the budget-conscious grower as it can be costly to purchase and maintain. This soil is best suited to larger grows in which you compost a lot of soil all at once. So, if your cannabis garden is on the small side, you may want to put off using super soil until you're overseeing more plants.
  • Strenuous: Mixing super soil can be a workout. But if you enjoy the physical challenges of cultivating cannabis, then this one may be a perk rather than a pitfall.
  • Slow: Composting can take up to 60 days before the soil is ready to use so planning ahead is essential. Super soil can also be slow in terms of overall plant growth, notably in the vegetative stage. If you're seeking a quick crop, you may prefer to use liquid nutrients rather than super soil. 

How to grow weed with super soil

Composting your own soil is an investment that may reward you in both quantity and quality when harvest time arrives. To get started you'll need:

  • Mixing container large enough to hold up to 110 pounds of soil
  • Traditional gardening rake
  • 4 extra-large trash cans to hold the soil during composting
  • Up to 210 pounds of organic soil
  • 70 pounds of light mix soil

Those five ingredients form the basis of your soil composting mix, but there are plenty of goodies that you can add to super soil to maximize its potency. Among these beneficial ingredients are bone meal, bat guano, and worm castings. All of these organic materials work with the nutrients already present in super soil to create a powerhouse recipe for cannabis growth. Earthworm castings and fish bone meal are especially powerful ingredients to blend into super soil. Consider mixing in this combination of supplemental ingredients:

  • 60 pounds earthworm castings
  • 6 pounds fish bone meal
  • 5 pounds blood meal
  • 4 pounds bat guano

The finishing touches for this recipe are needed in much smaller quantities. Once you've gathered the above ingredients, you've done most of the heavy lifting and now need just a few more items:

  • 1 cup dolomite lime
  • 3/4 cup Epsom salts
  • 1/2 cup Azomite

You can mix in a couple of ways. The first way, which is not recommended, is to simply mix everything together in a pile. Such a rushed approach will not permit the ingredients to blend properly, so we recommend a more layered and methodical strategy for the best results. Here is everything you'll need to do in 12 steps:

  1. Add 2/3 (140 pounds) of organic soil to your designated mixing container. If you don't have a container that's large enough, you can use a tarp or even a children's swimming pool.
  2. Mix in the fishbone meal.
  3. Add half (35 pounds) of the light soil mix and cover up the stench of the fishbone meal by using your rake to combine the ingredients.
  4. Sprinkle the lime over the entire surface of the mixture.
  5. Sprinkle on the Azomite.
  6. Add the remainder of the light mix soil (35 pounds).
  7. Add half (30 pounds) the earthworm castings.
  8. Add the final third of the organic soil (70 pounds).
  9. Rake the mixture again.
  10. Pour in the rest (30 pounds) of the earthworm castings.
  11. Add blood meal, bat guano, and Epsom salts, if using.
  12. Rake and stir the entire mixture again until it is thoroughly blended.

The next part of the process is composting, which will require up to 60 days to complete. Take a week to continue mixing the ingredients until they are fully blended and you don't see any more pockets of color. The mixture should be an even earth-tone brown.

After the mix is fully blended, transfer a quarter into each of the four garbage cans. Pour in some water to make sure the microbial process gets underway, keeping everything moist but not soggy. At this stage, it is important to put lids on the trash cans so that the mix does not dry out. If the mix does dry out, the composting process will halt as the all-important microbial activity ceases. Lids are also important to keep out insects, which will be drawn to such a fertile environment and could contaminate it.

Leave the covered trash cans in a sunny location for 30 to 60 days. Continue watering the mixture during this period, always maintaining vital moisture without drenching it. This period of the composting process is called baking because the mixture will become hot to the touch as the sun bakes it. The heat emanating from the mixture breaks down the soil ingredients so the cannabis plants can absorb them. You may opt to add live worms to the mix, which will help aerate the growing medium and keep the soil healthy. Either way, mix everything one last time for good measure.

Once you have completed all these steps, the final product will be an organic soil ready to use for indoor or outdoor cannabis cultivation. The recipe is appropriate for any type of pot and any size batch you wish to produce. You can also think of your creation as smart soil as it will be mostly maintenance-free.

How do you make Subcool's super soil?

For a slight twist on the standard super soil recipe above, consider Subcool's. This popular recipe has been around for more than two decades and is known among organic cultivators as one of the best mixes for growing top-shelf marijuana. Rock phosphate and humic acid are two notable components in Subcool's recipe. To make a large batch of your own Subcool super soil, you will need the following ingredients:

  • 8 ten-pound bags of organic potting soil of the highest quality your budget will allow
  • Up to 50 pounds of earthworm castings
  • Approximately 5 pounds each of fish meal, bat guano, and blood meal
  • About 3 pounds of rock phosphate
  • 1 cup of dolomite lime
  • 3/4 cup of Epsom salts
  • 1/2 cup of Azomite
  • 2 tablespoons of powdered humic acid

After the ingredients are thoroughly blended, add in enough water for the mix to be moist but not soaking wet. This action helps activate the microbial activity that makes organic soil so potent.

Once you've watered the mix, it's time to bake it in the sun as you would do if you were making a compost. The cooking process breaks down all the component ingredients and prepares the soil for successful planting. As with generic super soil recipes, since you've added nutrients, there will be no need to fertilize. Simply transfer the Subcool super soil into large pots that can hold up to 10 gallons and start planting.

Premade soils for planting cannabis

If you don't have the time to make the soil from scratch, you have several other options. One possibility is to purchase composted soil from a nursery or garden supply store. This premade soil can be a time-saver while still providing many of the same benefits of the DIY version. Of course, premade soil often comes at a premium price, so assess whether you would rather save time or money before deciding which growing medium is right for you.

cannabis super soil
Premade soil can be a time-saver while still providing many of the same benefits of the DIY version.
Photo by: Gina Coleman/Weedmaps

The bottom line on super soil

Making super soil is an excellent choice for the serious grower who wants to produce a high quality, large yield of cannabis and has the room to mix up a batch of soil.

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The information contained in this site is provided for informational purposes only, and should not be construed as medical or legal advice. This page was last updated on September 8, 2020.