Getting and managing good soil for marijuana growing is a challenge.
Most hydroponics stores sell the same 1-3 major brands of soil, including Fox Farm and Roots Organics.
Some growers feel that good soil for marijuana growing can be found at garden supply stores or discount stores like Lowes, Home Depot, and Wal-Mart.
They buy Miracle-Gro, Espoma, Dr. Earth, and other soils. I don’t like any of those products, because they have low quality and/or additives that you don’t want in soil for marijuana growing.
Nor do I like to buy anything from corporate stores, especially Wal-Mart.
I prefer Fox Farm and Roots Organics if I have to buy commercial soil.
Occasionally you find good regional soils such as Fafard, Black Gold, or Potters Gold that are made in custom-crafted batches and are of higher quality than nationally-available soils.
Building your own soil for growing marijuana is very hard, even if you attempt to follow the instructions from TGA Seeds guru Subcool, who has created a recipe for what he calls “supersoil.”
The problem isn’t the recipe—it’s finding the many raw materials that Subcool’s supersoil recipe requires.
No matter what you choose as your soil for marijuana growing, get the best soil for your marijuana plants by using these strategies:
- Contact the manufacturer and ask for a complete list of all ingredients, especially if there are added fertilizers, wetting agents, chemicals, or beneficial microbes.
Many commercial soils contain hidden ingredients you don’t want in your soil, but those ingredients aren’t all disclosed on the packaging.
Avoid Miracle-Gro products, even the ones that claim to be organic.
Miracle-Gro is an enemy of the marijuana community, and they’ve caused many problems for gardeners and others because their products have been defective or mislabeled.
You don’t want any added fertilizers, wetting agents, or pesticides in your soil.
It’s ok if your soil includes added beneficial microbes.
- Ask the manufacturer what’s the N-P-K rating for the soil, as well as the soil pH.
If the N-P-K is any higher than 1-1-1, or if the soil has added chemical fertilizers, don’t use it, especially for starting seeds.
- Bring a magnifying glass to the retail store and examine the soil before you buy it.
Take a couple of handfuls of sample soil and carefully look at it to see if there are any pests, pest eggs, shards of glass, dust, stones, molds, or spores.
You’re also looking for the amount and percentage of sticks, bark, stones, twigs, non-decomposed material, sand, or other filler.
If you see a lot of sticks, bark chips, and other non-fine materials, and especially if you see evidence of pests, molds, and spores, avoid that soil.
- When you’re handling the sample soil, let your hands, nose, and eyes be your guide.
Good commercial soil for marijuana growing feels slightly moist just out of the bag.
It will be golden brown, dark brown, or rich black.
It won’t be crumbly like desert soil but will feel “organic” and alive.
It will smell earthy, but not musty, foul, or moldy.
Think: soil from a forest floor in a lush forest. That’s what you want.
- Look for the amount and percentage of perlite, as well as the size of the perlite granules used.
Many soil companies fail to blend in enough perlite, and/or they use perlite that’s too-small in particle size.
I always keep several cubic feet of extra-coarse, clean, washed perlite on hand when I use soil for growing marijuana, and often have to add lots of perlite to bring the soil up to the aeration porosity I prefer.
This is what I use.
Especially if you’re growing indoors, have worries about high soil moisture, or tend to be overwater, you want your soil to be 15-25% coarse perlite.
This provides lots of soil space for oxygenation, root movement, and works against the kind of sogginess that rots roots.
Take a look at the two photos I provided in this article to see examples of soil that’s healthy, the right color, free of fillers such as sticks, and has the right ratio of coarse perlite.
In the next article in this series about soil for growing marijuana, you’ll learn how to fill containers, how to water, how to get the right ratio of perlite, and other professional soil for marijuana growing tips.