best growing medium for cannabis

Best growing medium for cannabis

When growing cannabis in containers, for example with soil or coco, it’s important to give your plant roots enough room to grow. If they run out of space, it will limit the size of your plant, and often causes nutrient deficiencies and other problems like persistent droopiness. If your roots have circled around the edges of the container, it is rootbound and should be transplanted to a bigger container immediately!

With living soil, a colony of microorganisms in the soil creates an ecosystem that mimics the best-of-the-best soil in nature. The nutrients are slowly broken down from organic sources and delivered directly to your plant roots. For some reason, plants grown in this type of root environment tend to produce very strong-smelling buds. One thing that’s really great about living soil is you usually don’t need to use any added nutrients.

Believe it or not, the best overall medium – in my opinion – is coco coir!

DWC is one of the few types of hydroponics that can support larger plants. Other types of hydroponics (for example NFT or Aeroponics) have a difficult time growing plants as big and nutrient-hungry as cannabis.

Common Cannabis-Friendly Soil Mixes in the US:

Another cool thing about coco coir is that it’s renewable, so it’s easier on the environment. Most soils use peat which is a finite resource, and hydro can add nutrient water to the water supply. Properly used coco coir doesn’t have any of these problems so you can feel good about using it. Unfortunately, perlite – which is almost always used with coco coir – isn’t renewable, so in a sense, coco coir isn’t renewable because of its dependence on perlite.

Example of cannabis roots growing directly in a solution of nutrient water

Every Grow Medium Must Help Roots Get What They Need: Water, Oxygen and the right Nutrients

Common Cannabis-Friendly Soil Mixes in the US:

Soil or compost is one of the most popular growing mediums for marijuana plants because it is natural, easy to use, and available everywhere.

Plants in soil grow a little slower than in coco or hydro, but soil-grown buds tend to have a stronger smell/taste. Although using a standard soil potting mix and giving nutrients in the water gets results similar to coco, using amended and composted living soil tends to produce buds with a powerful and complex scent/taste profile.

Best growing medium for cannabis

However, when added to a cannabis growing medium, peat moss massively increases water retention and introduces beneficial microbes that help make nutrients more available to plants.

On the downside, soil can harbour pathogens and pests that could harm your plants. Additionally, the natural growth rate in soil is less than in other growing mediums. Some of which can support larger cannabis plants and greater cannabinoid yields.

If you can’t settle on a suitable growing medium, you can always mix and match. Adding coco coir to soil, for example, improves its structure and increases water retention and oxygenation.

Rockwool is the brand name for a type of mineral wool that is made from volcanic rock. Like coco coir, it has excellent drainage and aeration and has become a popular growing medium for cannabis.


Perlite, meanwhile, is a lightweight material made from volcanic glass, which attracts oxygen to its surface. Many cultivators add this to their cannabis growing medium to enhance aeration and minimise roots’ energy when seeking out nutrients.

Unlike coco coir, however, Rockwool is neither organic nor biodegradable. Its production involves intense industrial processes that are not environmentally sustainable. On the flip side, the fact that it contains no organic matter makes Rockwool impervious to harmful bacteria and fungi, drastically reducing the potential for plants to become diseased.

The sexy parts of your cannabis plants may be above ground, but it’s down in the root zone where the real magic happens. By taking in nutrients, water, and oxygen, a plant’s roots provide everything it needs to grow and produce top-quality bud. The growing medium largely influences the ability of a cannabis plant’s roots to do so, so picking the right substrate is a pretty important decision.

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Because soil contains many microorganisms that help regulate all aspects of the environment, much of the work is taken care of with little input required from the grower. Fluctuations in pH or other variables generally have less drastic consequences than they would in other growing mediums. So there’s more room for making mistakes.

Many commercial soils also come packed with nutrients, so there’s no need to add any extra fertiliser or plant feed. Not for t the first few weeks of the growth cycle anyway. Soil is also the most natural and environmentally friendly cannabis growing medium.