Why Picking the Best Soil Is the Most Important Step in Cannabis Growing

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Dirt isn’t necessary. You don’t need soil to grow your marijuana. There are soilless options like coco coir, perlite, and vermiculite. Some growers like the fast and full yields promised by hydroponics. And, recent growers are experimenting with aquaponics and aeroponics. The push for more volume and quality control presses growers to seek the most efficient farming methods.

But, for those committed to growing their marijuana in soil, picking the best soil may be the most important step you take.

Making your own soil

Grow Weed Easy suggests, “Your absolute best option would be to compost your own soil (or purchase composted soil) which gets incredible taste results but does take a little more work (or money if you buy it).”

But, when we talk “soil,” we don’t mean “dirt.” Soil is a prepared growing medium, one you can make or one you can buy.

Creating your own begins with a base of organic soil. With help from your local nursery, you can mix a balanced organic soil containing ingredients, such as bat guano, coco fiber, compost earthworm castings, greensand, lignite, peat moss, oyster shell dust, perlite, pumice, oyster shell flour, and soybean.

Marijuana Times offers a simple recipe for starters to create 1-cubic foot of soil: Using a 5-gallon bucket as your measure, add and mix ½-bucket of peat moss or coco coir, 1/2 -bucket aeration amendment, and ½-bucket humus.

  • Opt for the coco coir which lacks the acid base of peat moss or you will have to balance the acid with dolomite lime.
  • Add an aeration amendment like pumice, rice hulls, or perlite to loosen the soil to improve drainage and oxygen distribution.  
  • Select a fine compost that is rich in earthworm castings.

Once you mix the base, you add amendments that balance and enrich the soil. As you add the ingredients, turn over the composition frequently. You might add four cups of rock dust, 2 cups of kelp meal, and 1 cup of alfalfa meal.

Continue to turn and mix before allowing it to sit and settle. After a break, resume turning, mixing, and watering over two weeks of “cooking.” By that time, you should have the “dirt” you need for planting.

Buying what you need

The best marijuana soil is dark, rich, and loose. It drains well but holds water well.

  • If you are growing from seeds, you want to launch the plant’s growth without problems. Sterile soils eliminate disease, fungus, and other pathogens. But, sterile soil also prohibits beneficial microbes. So, you want to strike a balance in which nitrogen fixing microbes encourage beneficial fungi and bacteria.
  • Commercial packaged soils are processed and marketed without the time for the contents to cook and mature. But, you can look for one with fine texture and no bark or wood. Read and compare the ingredients.
  • Treat seeds well. Quality seeds from quality vendors are germinated and waiting to grow. If you lay a damp paper towel over the seeds, they will crack through their shells. Using gloved hands and tweezers, you can move the cracked seeds into the prepared soil in divided planters formed of coco fiber.

The recommended commercial soils

Cannabis growers regularly recommend the same products. That’s one sign that the market has not grown much, but it also makes choices easier and more confident:

  • Most amateur marijuana farmers recommend Fox Farm’s Ocean Forest® as the ultimate mix of bat guano, earthworm castings, crab mean, and fish meal. They claim it’s ready to use from the bag, but you may want to amend it as your experience with different strains warrants.
  • Ideal 420 Soil™ is one of the few specifically geared to cannabis marketing. The bag identifies ingredients as: he ingredients were listed as Canadian Peat Moss, Vermiculite, Silica Sand, Calcium Clay, Rock Phosphate, Sulfate of Potash, Humic Acid, Fulvic Acid, K-Mag, Glacial Rock Dust, and Azomite. It comes with instructions to “just add water,” and the claim that it will support the growth of a plant throughout its cycle.
  • Roots Organic Formula 707 by Aurora comes in a bag and encourages you to plant directly through piercings in the bag. That wouldn’t work well with cannabis plantings, but the organic soil is a productive combination of fine ingredients with greater water-holding capacity.
  • Sunshine Advanced-Mix 4 will double its size when broken apart. It’s an organic base of Canadian Sphagnum Peat Moss mixed with perlite, coco coir, dolomite lime for pH control, and wetting agents. It claims high water retention and aeration.
  • Miracle-Gro® Potting Mix in just about every store. It has been the go-to mix for home gardeners for generations. But, marijuana cultivators have some problems with it. Miracle Gro® products are low-priced and considered premium. But, because it is locally sourced, the product is not the same region to region. This means you’ll want to check the ingredients. Those who promote hydroponics and strict organic methods warn the Miracle Gro® chemical content will leach into the weed as an ammonia taste.
  • Black Gold® offers a selection of potting mixes, some specifically compounded for plant families. But, they also sell individually packaged amendments like earthworm castings, perlite, coco coir, peat moss, and more from which you can mix your own super soils.

There is a real market niche for cannabis growers. Their increasing numbers, growing indoors and out, growing organic or not will drive innovation in product development in soils and other farming supplies.

Picking the best soil for your plants may be the most important step in marijuana growing, but right now that means mixing your own if you want the best results. Otherwise, you can find what you need for growing your few plants at home with supplies from your local big box store.