Beneficial Microbes for Cannabis

Growers often take a minimalistic approach to plant health, focusing only on what is necessary to keep the plant alive. In doing so, we often forget that life has created a sophisticated network of symbiotic relationships between organisms over the course of millions of years. The soil food web is one such system that plays a critical role in the overall well-being of plants.

Sure—you can grow great cannabis using inert media and synthetic nutrients, but you are missing a crucial component to plant vitality. By supporting the growth of bacteria, fungi, and other beneficial microbes in your medium, you can create a thriving ecosystem that allows plants to reach their full potential. As a result, you’ll be rewards with buds that are more potent and flavorful.

Benefits of Microbes for Cannabis

There are many advantages to growing with microbes, no matter which media or nutrients you use. Beneficial microbes can support plants by:

  • Aiding in nutrient and water uptake
  • Stimulating root growth
  • Fighting off harmful microorganisms
  • Fortifying against stress and diseases

One of the perks of using microbes is that they allow you to grow organic cannabis. Most organic fertilizers aren’t immediately bioavailable to plants. Therefore, you’ll need microbes to break down the amendments into plant-available nutrients. And because microbes free up organic matter in the soil, you can save money by using less fertilizer.

Another benefit of incorporating microbes into your grow is that they can help you feed your plants more efficiently. They make the right amount of nutrients available at the right time, taking the guesswork out of growing. This can help to prevent over- and under-fertilizing the plants.

Microbes also make your plants better able to handle stress. With a large colony of bacteria and fungi looking after your plants, you won’t have to worry as much about pests, diseases, and environmental stressors such as pH and temperature swings.

Because your plants aren’t constantly battling pathogens, they can to put more energy into developing terpenes, flavonoids, and cannabinoids. As a result, you’ll be able to grow more potent and flavorful buds.

The Soil Food Web


Unlike synthetic fertilizers, organic inputs aren’t always bioavailable to plants. Cannabis relies on colonies of microbes to turn bat guano, bone meal, and other organic compounds into plant food. This collective of fungi, bacteria, oomycetes, and archaea is part of a microbiome known as the soil food web.

Plants influence the microbiome by releasing exudates from their roots. These carbon-rich materials inhibit the growth of harmful pathogens while attracting beneficial microbes to the rhizosphere. This creates a symbiotic relationship in which the microbes feed on plant exudates while breaking down organic matter for the plants to absorb.

Over millennia, plants have adapted to rely on microbes to survive. In fact, evidence suggests they can control the type and number of microbes in the soil depending on which exudates they release. During different stages of plant growth, populations of microbes change to serve the nutrient demands of the plant.



Mycorrhizae are one of the most important microbes for plant health. The mycelium of this fungi binds with plants at the root zone and feeds on the exudates secreted from the roots. In turn, mycorrhizae serve as an extension for the roots, allowing plants to uptake more water and nutrients from the soil.

Mycorrhizae come in two varieties: ectomycorrhizae, which live on the outside of roots, and endomycorrhizae, which live inside of the plants. Both types of fungi play a role in influencing mineral uptake, water absorption, growth, and disease resistance in cannabis plants.


Beneficial rhizobacteria are bacteria that colonize root zones and form symbiotic relationships with plants. Like fungi, these microbes help plants uptake nutrients while protecting them from harmful pathogens. They also decompose organic matter, making it bioavailable for plants.

Together, fungi and bacteria act like an immune system for plants. They work in tandem to increase nutrient uptake and assimilation, improve soil texture, secrete and modulate extracellular hormones, secondary metabolites, antibiotics, and signal compounds, and—most importantly—enhance plant growth.

How To Promote the Growth of Beneficial Microbes in Soil

Like most living things, microorganisms need food, water, and oxygen to survive. Gardeners can take several simple steps to support the growth of beneficial microbes. These include:

  • Feeding microbes with organic matter
  • Keeping the medium warm and moist
  • Aerating the soil to provide oxygen 
  • Minimizing the use of synthetic fertilizers

Organic Matter

One of the most effective ways to promote the growth of beneficial microbes is to incorporate compost into your garden. Compost is rich in organic compounds that microbes need to survive. It also helps to buffer the pH of the soil, which further supports the growth of microbes. High-quality compost contains millions of microorganisms that will quickly colonize your plants’ root zones.

Moisture and Warmth

Keeping the growing media warm and moist is essential for beneficial microorganisms. If the soil becomes too dry or the temperature fluctuates too drastically, bacteria, fungi, and other microbes will die. Applying mulch is a great way to keep the soil moist and protect microbes from the sun’s rays.


On the other hand, you need to keep the soil well aerated to supply oxygen to the roots and microbes. Allowing the growing medium to become too moist can prevent oxygen from reaching roots and microorganisms. Using amendments such as compost, perlite, and vermiculite can help aerate the soil, ensuring the microbiome receives sufficient oxygen.

Synthetic Fertilizers

Finally, growers can protect microbes in the soil by limiting the use of pesticides and synthetic fertilizers. Chemical pesticides, herbicides, fungicides, and fertilizers can kill entire populations of microbes quickly. One or two applications of synthetic nutrients during a growing season might not be detrimental. But salts can build up over time within the soil, creating an inhospitable environment for microbes.

Final Thoughts on Beneficial Microbes for Cannabis

If you aren’t incorporating microbes into your grow, you’re missing a crucial element in cultivating top-shelf cannabis. Hydroponic and organic gardeners alike can benefit immensely by supporting the growth of microbes in their gardens. By following the tips outlined in this article, you’ll be able to create a soil food web that protects your plants from pathogens, feeds them the right nutrients at the right time, and allows them to reach their full potential.

Have you tried incorporating beneficial microbes into your grow? Please share your experience in the comment section below. While you’re here, check out our collection of regular and feminized cannabis seeds.

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