What’s the best soil for growing marijuana?
When it comes to growing cannabis in soil, it’s imperative to choose or create a blend that will allow your plants to perform their best. Soil, at a basic level, is defined as the topmost layer of earth in which plants grow, a mixture comprised of organic remains, clay, and rock particles.
But when perfecting an environment for high-quality cannabis, there is much to consider. Soil varies in a number of common ways, such as:
- pH level
- Water retention
- Nutrient makeup
In this article, we’ll look at what traits make up the best soil for cannabis to help support a healthy garden.
Check out these additional resources on soil and planting:
Traits of quality soil for cannabis
Soil is generally described as having a mixture of sandy, silt, or clay textures. The texture directs the overall structure of the soil, so when it comes time to put your cannabis seeds in the ground, be mindful of its attributes.
- Large granular size
- Low pH
- Pros: Good drainage, prevents compaction, easy to work with, high oxygen levels
- Cons: Poor water retention, dries out quickly, nutrients get washed away
- Medium granular size
- Pros: Naturally fertile (contains nutrients), retains water, stabilizes plants
- Cons: Poor drainage and easily compacted
- Small granular size
- High pH
- Pros: Provides minerals, retains water, stabilizes plants
- Cons: Poor drainage, heavy soil, hard to work with
While some plants thrive in their native soils, which are dominated by one of the compositions listed above, cannabis plants are best grown in soil that includes a combination of those three textures and properties. This mixture is known as loam.
What does loam soil look like?
The best way to identify loamy soil is by touching it. How does it feel? Sandy soil should be difficult to compact while clay should compact into a tight ball that won’t crumble. When squeezed, loamy soils should form a loose ball that will hold its structure momentarily before breaking apart in large chunks.
Here are some qualities of loam soil:
- Mixture of sand, silt, and clay
- Near neutral pH
- Pros: Drainage, water retention, naturally fertile, easy to work with, nutrient retention, supports microorganisms, high oxygen levels
- Cons: Can be costly
Most potting soils used in gardening are loam soils. If you’ve ever worked with potting soil, you’ll know that its composition is rich and diverse, and it looks dark and hearty. Beyond texture and color, the soil should smell rich and alive.
Buying the right soil for cannabis
While shopping for soil, you might be overwhelmed by the options available at your local garden store. You now know that most of these soils will be loamy, but why are there so many different types?
Consider the soil type as the basic structure of your soil. From there, look at nutrients, microorganisms, and other amendments that improve your soil. Your choices will be flooded with words like:
- Worm castings
- Bat guano
- Peat moss
- Fish meal
- Bone meal
- Glacier rock dust
- Plant food
These are just some examples of amendments that are commonly listed on different types of soils. Heavily amended soils will have long lists that break down all organic nutrients they contain. Some companies create soils that offer a great structure with base nutrients, but allow you to fill in the gaps as you desire.
For most first-time gardeners, we recommend buying a quality potting soil that will provide your plants with enough nutrients to get them through most of their growth cycle without having to add many amendments or liquid nutrients.
This post was originally published on January 10, 2018. It was most recently updated on June 29, 2020.
Having the proper soil is important to growing a strong and healthy cannabis plant. Learn what types of soil are out there and what to look for with cannabis.
The 5 Best Soils for Growing Weed
If growing cannabis is an art, then the soil is the canvas, paint and even a little bit of the brush. As your “grow medium” (the material that your plants grow in), the balance of nutrients your soil contains shapes how your plants grow, how fast and abundantly they flower and how many buds they yield.
Cannabis plants spring up like a literal weed. But growing weed optimally — in a way that allows it to express its best traits and produce trichome-rich flowers — demands care, attention to detail and a bit of trial-and-error. At the same time, there’s no better way to develop a closer, more connected and more rewarding relationship with cannabis than growing some yourself. To get you started, here’s our list of the five best soils for healthy weed.
Fox Farm’s Happy Frog Potting Soil
Fox Farm’s specialized line of soils for cannabis are some of the most widely acclaimed grow mediums available. If you’re beginning your grow journey from the ground up, Happy Frog is an excellent soil to nurture seeds and seedlings.
Designed for indoor and outdoor cultivation, Happy Frog potting soil takes care of young cannabis plants’ essential needs, from correct pH levels to balanced nutrients, including a vital combination of microbes and fungi from earthworm castings and forest humus.
Nature’s Living Soil Organic Super Soil
From planting seeds to harvesting buds, Nature’s Living Soil’s Organic Super Soil has you covered through cannabis’ entire grow cycle. Reviewers love the ready-to-use simplicity this soil provides: just plant, water and wait. For those growing on their own for the first time, this is one of the best soils you can buy.
If you’re digging through the literature on growing weed, you’ve probably seen the term “super soil” come up quite a bit. Coined by the legendary grower and seed producer Subcool, the term generally describes a neutral organic soil base that’s been enhanced with a comprehensive range of “amendments,” i.e., added nutrients and microorganisms. Using a super soil eliminates the need for liquid nutrients as your cannabis plants grow.
Red’s Premium Biochar-Based Soil
Red’s Premium is another all-in-one, ready-to-use soil blend. But what makes it one of the best soils for weed is its stand-out feature: biochar. Biochar is an amendment that excels at protecting and promoting the growth of bacteria, fungi and other microorganisms that are essential for root development and strengthening your plant’s immune system.
Your soil’s nutrients and the water you provide need to link up to be available for and absorbed by plants’ roots. Biochar, a carbon-rich charcoal amendment, not only facilitates this process but it also provides a large surface area for microorganisms to live and thrive. Red’s Premium Biochar-based soil thus creates an ideal “habitat” for all the living beings that help your cannabis plants reach their full potential.
Aurora Innovations Roots Organics Formula 707
If you’re planning on planting a large container cannabis garden outdoors, Roots Organics Formula 707 is a versatile and capable option. An organic soil designed with greater water-holding capacity, Formula 707 contains ingredients and beneficial microbes specific to using larger containers.
But just as important as what’s in this soil is what’s not: less perlite, less pumice, and fewer amendments. This makes Formula 707 a highly customizable soil, allowing you to add your topsoil and liquid nutrients at various growth stages depending on your cannabis plants’ needs.
Still, Formula 707 has enough nutrients to last 10-14 days before you need to add anything. And for convenience, you can use the soil bag itself as a pot. Just cut off the top, poke some holes in the bottom, plant your seedlings and you’re ready to grow.
Sungro Black Gold All-Organic Potting Mix Plus Fertilizer
The best soils for weed don’t always have to be products specialized for cultivating cannabis. Sometimes, a good organic potting soil is all you need, and Sungro’s Black Gold all-organic potting soil is an excellent case in point.
At a price point that won’t put a hole in your pocket, Black Gold boasts all of the essential traits of a strong soil for growing weed. Its loamy mixture contains an optimal blend of pumice and perlite for hydration and microorganism development, and its balanced nutrient blend won’t burn young cannabis plants. Those features have won this soil praise from gardeners of all stripes, cannabis growers included.
Every ingredient in Black Gold is organic, and it’s suitable for a wide range of environments, from patio containers to indoor hanging baskets. The bottom line: Black Gold is a reliable and high-performance base soil for cannabis. You can also get hands-on with this soil, since adding amendments as your plants grow is super easy.
Featured image by Gina Coleman/Weedmaps
The balance of nutrients your soil contains shapes how your plants grow, how fast and abundantly they flower and how many buds they yield.