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The Best Type of Soil for Growing Cannabis

Last updated: April 24, 2020

best soil

If you’re not into growing cannabis hydroponically or without soil, then you must know what’s the best soil for the plant. This article aims to help growers cultivate their own marijuana plants with the best type of soil there is.

The Characteristics of a Fine Cannabis Soil

If you want the plant to flourish, and by that I mean produce THC, trichomes, and other cannabinoids, then you need to use the best soil even if you know that cannabis can develop in a vast array of soils.

How will you know the soil is good enough for your cannabis? If it has the following characteristics:

Ideal Organic Soil
  • Correct ratio of nitrogen and phosphorus
  • Great water retention
  • Proper drainage
  • Soil pH of 6 (more of this later)
  • The appropriate equilibrium of fungus to bacteria (remember that cannabis prefers soil that’s slightly acidic)

The Ideal Soil pH Level for Cannabis

It’s important to understand the pH (potential of hydrogen) levels when talking about soil because it tells you how basic or acidic a substance is. Everything below 7 and acidic—like lemon juice (pH 2) and coffee (pH 5)—while everything above 7 is basic—like seawater (pH 8) and baking soda (pH 9.5). Pure water is neutral because it has a pH level of 7.

Because soil has water, it obviously has a pH level. And because cannabis likes a slightly acidic soil, we’ll talk about why the perfect pH number is 6. If the soil has this number, it will allow the cannabis plant to flourish. If it goes a bit lower than 5.8 or higher than 6.3, the plant can still sustain itself but don’t expect it to produce excellent yields.

Cannabis Soil

Featured Image Credit: rexmedlen, Pixabay

The Ideal Soil for Outdoor-Grown Cannabis Plant

If you’re growing cannabis outdoors, that means the natural soil may either be sandy, clay, or loamy. However, some soil can be a combination of these types—they can also be clay+loamy, sandy+loamy, sandy+clay, etc. And of course, each type of soil has its pros and cons.

If you have no choice but to cultivate your marijuana plants in the natural ground outside, then it’s best to dig a hole that’s 3-foot wide and 3-foot deep, and fill it with organic soil. Do this and your plant will receive proper water retention, drainage, and nourishment to aid it develop and be strong.

You can also use pots if you wish. You can place three- to five- gallon buckets or pots outside and fill them with organic soil (this will be described later). Make sure you check the amount of sunlight, temperature, rainfall, humidity, and pests.

The Ideal Soil for Indoor-Grown Cannabis Plant

Just like in the previous section, the finest soil for your indoor cannabis is also organic soil. However, it should be combined with fertilizer.

On the one hand, the organic soil will be responsible for giving the proper balance of nutrients, carbon, phosphorus, and nitrogen to make sure your plant will receive precisely what it requires for each growth stage.

On the other hand, the fertilizer will help the plant grow tall and produce loads of cannabinoids.


credit: Francis Chung, Flickr

The Ideal Potting Soil

If you’re going to purchase a bag of soil from a garden store that has very few choices, make sure to look for the words “organic potting mix” or “organic potting soil.” It isn’t the perfect soil for the job, but it can do the trick.

Remember that you don’t want any slow-release chemicals to exist in your potting soil for cannabis. Time-released chemicals in soils could deliver incorrect nutrients to your marijuana plants at the worst possible time. These nutrients spell catastrophe and could damage your entire crop. However, if the store you’re buying from has a wide variety of choices to pick from, pick any of these organic soil brands:

Fox Farm Soil

This brand is also worthy to be mentioned. It’s another bag of soil used and loved by cannabis growers. The favorite of many is the Ocean Forest Mix because it’s primarily efficient at providing the appropriate soil conditions for your cannabis plants to grow to their full potential. Cannabis plants love this mix because it includes the following ingredients: bat guano, composted forest humus, crab meal, granite dust, Norwegian kelp, oyster shell, sandy loam, sea-going fish emulsion, shrimp meal, sphagnum peat moss, and worm castings.

Cannabis Best Soil

Featured Image Credit: Pxfuel

Black Gold Soil

This type of soil has proven its effectiveness for years. It’s the go-to soil for the cannabis grower. The brand even makes other preservatives like perlite, peat moss, compost, vermiculite, and earthworm castings, which you can utilize to augment the shortage of essential nutrients.

The Ideal Organic Soil

If you don’t want to purchase a bagged soil and you’d rather make one, then you can follow these steps to make your own organic soil:

  • Lay down a 4-inch layer of dry leaves or straw and let it cover a 3×3 square.
  • Add another 4-inch layer of coffee grounds or livestock manure.
  • Top those layers with a 1/2-inch bone meal.
  • Repeat steps 1-3 until the pile is 3ft. high.
  • Let the pile decompose.
  • Turn it once a week—never as frequent as every three days.

You’ll know the process is complete once the soil turns dark black, is crumbly, soft, and smells sweet.

The Ideal Soil for Auto-Flowering Cannabis

The role of light in plant growth throughout the day is crucial for the cannabis plant to flower. These photoperiod plants need 12-15 hours of light every day if grown outdoors. The problem is they don’t usually receive this amount of light until late summer. If you grow cannabis plants indoors, however, then you can completely control the amount of light the plants will receive.

Now, you should know that some marijuana plants can auto-flower—this means they’re not dependent on how much light they receive for the flowering phase. Alternatively, they progress to the flowering period when they reach a particular period of development.

Auto-flowering cannabis plants prefer lighter and airier soil with low nutrients. That means the types of soil we mentioned above aren’t ideal for them. But it doesn’t necessarily mean that you can’t utilize regular or ordinary soil. We’re saying that the results will be better if you use a lighter soil.

Here’s a recipe for you so you can mix your own auto-flowering soil:

Auto-Flowering Soil Recipe
  • 1 part of wet vermiculite
  • 2 parts of wet perlite
  • 3 parts of compost
  • 3 parts of peat moss

Ready to grow your cannabis plants? Learn how to germinate a seed now!

Featured Image Credit: free-photos, Pixabay