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Essential Microbes for Cannabis Plants Growing In Soil

Added 14 August 2023

Growing cannabis is never a solitary activity unless you want it to be. During the process, you meet a lot of people, from passionate entrepreneurs that sell you seeds and equipment to fellow enthusiasts that help you along the way. You’ll be making many friends during your journey, but some of these friends work in a magical manner and you won’t even realize their importance. 

No, we aren’t talking about your friends you made here on GD, but the friends that live under the soil — microorganisms. These microbes thrive in the soil of your cannabis plants and if you befriend them, they can help you grow your plant unlike anything else. So, here’s everything you need to know about soil microbes for cannabis plants. 

Soil Microbes for Cannabis Plants

Soil Microbes for Cannabis Plants

Microbes are short for microorganisms in the gardening circle, and these microbes have existed for over three billion years. They’re some of the oldest life forms on our little blue planet. These microbes are diverse and play an important role in the ecosystem, right from developing and supporting to maintaining life. 

In fact, the reason we can breathe or even digest food is thanks to these microbes. And the same principle applies to plants, including cannabis. These microbes are also super resilient and can withstand extreme environmental conditions, from freezing cold to boiling hot. 

Scientists have discovered millions of species of microorganisms, but when growing cannabis, you only need to know about a few, including bacteria, viruses, and fungi. So, how do these microbes help your cannabis plant? Essentially, they live in the soil, forming symbiotic or beneficial relationships with plants, helping them grow better. 

For example, you would already know how crucial proper nutrients are for a healthy cannabis plant and a fruitful yield. So, if you want a healthy plant that produces excellent yield, the oldest trick in the book — as old as agriculture itself — is to use microbe-rich soil. Here, the microbes in the soil “fix” nutrients for your cannabis plant by promoting a rich, live ecosystem within the soil that creates the right environment for the roots. 

Types of Soil Microbes 

Types of Soil Microbes 

As mentioned earlier, there are literally millions of microbe species on Earth, but you only need to know about a few common ones that actually benefit your cannabis plant. Here are the types of microbes you must focus on while growing cannabis. 

1. Beneficial Bacteria

The first and perhaps the most important type of microbe for cannabis is bacteria. These beneficial bacteria species are essential as they break down and decompose organic matter, and as a result, fix nutrients for the cannabis plant. They also go a long way in preventing and eliminating harmful pathogens in the rhizosphere. 

For example, Pseudomonas fluorescens and Bacillus subtilis, two species of beneficial bacteria, are known for fighting pests, toxins, and diseases. 

In fact, these bacteria species are not only helpful for cannabis when they’re alive and active, but they also serve a purpose even in death. When they die, beneficial bacteria put out biofertilizers that can further improve your plant’s growth and health. These little organisms make a big difference for plants. 

2. Fungi 

Like beneficial bacteria, even fungi species can be beneficial for cannabis plants. They also help break down complex organic matter and fix nutrients for plants. One of the most popular fungi species is Glomus Intraradices, which forms a symbiotic relationship with the roots of cannabis plants, improving their ability to absorb water and nutrients. 

Just how beneficial fungi are for plants? If you’ve ever heard of infertile soil from chemical damage converting to fertile soil in a few years, it’s likely due to fungi. While we may hate fungi in general, beneficial fungi are a vital part of the ecosystem and without it, we wouldn’t have all the flora around us that we love. 

3. Protozoa 

Bacteria and fungi aren’t the only organisms to exist in the soil, and the former has a predator — a single-celled organism called protozoa. These organisms prey on bacteria (among other microorganisms), and in the process, release a lot of beneficial nutrients in the rhizosphere. 

According to experts, protozoa are primarily responsible for maintaining an ideal nutrient cycle within the soil, which makes sure the nutrients are present in a healthy ratio for the plants to consume. Without protozoa, soil-based plants would likely suffer nutrient problems due to imbalances and deficiencies

4. Nematodes 

Nematodes are another type of microbes that you should know about when growing cannabis in soil. These organisms are microscopic worms and some of them are beneficial while others are harmful to plants. So, depending on the species, these organisms may either help the plant by fixing nutrients by attacking harmful pests and bacteria or attack the roots of the plants. 

Symbiotic Relationship Between Microbes and Cannabis Plants

Symbiotic Relationship Between Microbes and Cannabis Plants

In nature, all organisms rely on others for survival, and this relationship is called symbiotic. An easy way to understand this symbiotic relationship is that it’s kind of like a barter system; for example, one organism fixes food for the second, which in turn protects the first one. 

This type of symbiotic relationship exists within the soil, too, between various microorganisms as mentioned above, and plants, including cannabis. Out in the free world, nature takes care of these symbiotic relationships, but in a cannabis garden, you promote this relationship to help your plant flourish. 

This is where the primary duty of microorganisms comes into play. They serve as nutrient fixers for the plant as a part of the symbiotic relationship. Essentially, these microorganisms convert organic matter into nutrients that can easily be absorbed by plant roots. But this process isn’t like other relationships, where for example, a rodent eats grass and then gets eaten by a wolf. 

In a microbe-plant symbiotic relationship, the microorganism doesn’t produce food directly; instead, the food is produced by the plant itself via photosynthesis, where chlorophyll converts inorganic energy to organic. From here, the minerals and carbon dioxide create organic matter that the microbes consume in the soil. 

When consuming the organic matter, the microorganisms start breaking down the matter, releasing nutrients and minerals. These minerals are then absorbed by the roots for the plant to use. So, in this relationship, the plant not only benefits from the microbes but the cycle benefits the microbes, too. 

Benefits of Soil Microbes for Cannabis Plants

Benefits of Soil Microbes for Cannabis Plants

Microbes like beneficial bacteria and fungi serve many benefits for cannabis plants, and they can play a major role in your plant’s growth, health, and yield. Here are some of the benefits of beneficial soil microbes and how they can make a massive difference in your cannabis garden. 

1. They Help Fix Nutrients 

As mentioned earlier, the most beneficial microbes in the soil are nutrient fixers for plants. In fact, their biggest contribution to plants is that they help plants consume nutrients that are available in the soil. These microbes convert various matter in the soil into nutrients that can be easily absorbed by the soil. 

Soil microbes like mycorrhizal fungi develop symbiotic relationships with the roots of the cannabis plant. Essentially, mycorrhizae help the roots increase their access to nutrients by extending their hyphae into the soil. They can draw out nutrients like phosphorus, zinc, and copper from the soil, making them readily available for plant absorption. This improved nutrient uptake helps the plants grow much healthier. 

In addition, mycorrhizal hyphae have the ability to penetrate crevices and pores present in the soil, thereby helping the plant explore a larger volume of soil than plant roots alone. In short, this exercise helps the fungi to access nutrients that may be present in pockets of the soil that the plant's roots cannot reach.

They also help to solubilize the nutrients as mycorrhizal fungi produce enzymes that break down complex compounds and minerals present in the soil. For instance, these enzymes help to solubilize nutrients like phosphorus that are critical for plant development by making them more available for plants to absorb. 

Remember, phosphorus, in particular, is typically immobile in sois, so the plants have limited access; however, the fungi help reduce this issue by releasing organic acids that dissolve them, making it easy for plants to access them. Apart from phosphorus, the fungi also help with other nutrients such as potassium, calcium, and nitrogen, and act as intermediaries to improve the exchange of nutrients between the soil and the plant. As you can see, this reduces the need to use fertilizers extensively. 

And, talking about a symbiotic relationship, the fungi help in transporting nutrients such as phosphorus from the soil to the roots of the plant and absorb carbohydrates produced by photosynthesis in exchange. Talk about an excellent barter system! 

2. They Suppress Diseases and Pests 

Many helpful bacteria and fungi not only produce nutrients but also produce antibiotics and other minerals that can eliminate and prevent harmful pathogens from thriving in the soil. They do so by producing chemicals like lipopolysaccharides, salicylic acid, and siderophores that can repel pathogens. 

Beneficial soil microbes, including certain bacteria and fungi, compete with harmful pathogens for resources and space. They also produce antimicrobial compounds that inhibit the growth of pathogens. By establishing a diverse and active microbial community, cannabis plants are better protected against diseases that could otherwise negatively impact their growth.

As a result, your plants don’t become exposed to such harmful pathogens that may cause diseases, making the soil safer for your precious cannabis plants. So, if you want to protect your plant from common soil-borne diseases, beneficial microbes are your best friend. 

3. They Aid Root Development 

Another major benefit of microbes is that they help the roots grow well. Essentially, beneficial microbes like bacteria and fungi repel toxins and other harmful microbes. Plus, some species of microorganisms take over certain root areas and help them absorb more nutrients. 

Beneficial microbes benefit the roots in two ways: protecting them from pathogens and improving their nutrient uptake. The result is a healthy root system that further improves the growth of your cannabis plant. 

The microbes also produce hormones that encourage the roots to grow more. Mycorrhizal fungi create an extensive network of hyphae, thereby extending the reach of the roots and helping the plants get better access to water and nutrients. 

4. They are Independent Organisms 

This benefit may be a bit selfish but beneficial soil microbes benefit you by taking the stress off your shoulder. When you grow cannabis in any other growing medium, you are responsible for providing the plant with nutrients. But since these microbes fix the nutrients for your plant, you don’t have to worry much. 

You can grow cannabis plants with minimal effort from your end, and it’s not surprising to see soil-based cannabis flourish with nothing but healthy soil and tap water. 

Important Beneficial Soil Microbes

Important Beneficial Soil Microbes

Now that you know the various types of microbes and how they benefit cannabis plants, let’s look at some of the most important microbes that thrive in soil. Here are some of them.

1. Mycorrhizae

We touched upon this symbiotic relationship earlier but let’s dive deeper into what makes it so important. Mycorrhizae refers to the relationship between plants and fungi. So, the portion of the fungus that lives underground is known as mycelium, and this part acts as an extension of the roots, enabling them to consume nutrients through them. 

The larger surface area of mycelium improves nutrient absorption. On the other hand, plants exude sugars that feed this fungus. But it doesn’t end here. In return, mycorrhizae provide plants with more moisture and nutrients via mycelium. 

Generally, mycorrhizae exist in two types in the soil; the first is known as ectomycorrhizae which thrive outside the roots, and the second is endomycorrhizal which lives inside the roots. If you want to use this type of fungi for growing cannabis, you can certainly do so but avoid using fertilizers and fungicides on your plant as they can harm the natural mycorrhizae colonies in the soil.

2. Rhizobacteria 

Rhizobacteria is a group of bacteria species that play an important role in the soil for plants. They recycle and fix nutrients for the plants while interacting directly with the root system, ensuring impressive results. 

Essentially, these bacteria species help your cannabis plant absorb more nutrients and prevent pests and pathogens. They fix one of the three macronutrients, nitrogen, which is essential for the cannabis plant’s growth; they convert atmospheric nitrogen into absorbable nitrogen for the roots. 

Another way these microbes fix nutrients for the plant is by decomposing and breaking down organic matter within the soil, which produces more nutrients for the roots to consume. And even when they perish, they release beneficial nutrients into the soil that nourish the roots. 

You can find many rhizobacteria products on the market that you can choose from, which help you establish a strong population of these bacteria in your cannabis soil. We recommend getting a product with a beneficial algal component that will protect these bacteria from pH fluctuations and fertilizers.

3. Azotobacter vinelandii

Nitrogen is one of the three macronutrients required by cannabis plants for healthy growth. But naturally, the nitrogen that’s present in the soil can’t be absorbed by the plants directly, and it needs to be converted into absorbable nutrients by bacteria. 

Fortunately, this is where Azotobacter vinelandii comes into play. These free-living bacteria convert nitrogen using nitrogenases (a group of enzymes), and since it has the highest metabolic rate of any living organism (as far as we know), they can thrive really well in most regions. 

4. Epiphyte Bacteria 

Another type of bacteria that not only lives in the soil but also on the leaves, seeds, and flowers is epiphytic bacteria, and one of the most popular species of this type of bacteria is Cyanobacteria. 

These bacteria live on the plant’s surface and release oxygen, which can turn poorly-oxygenated soil into an oxygen-rich growing medium for cannabis plants. As a result, they serve the primary function of oxygen fixing and helping the plant with the transpiration process. 

5. Endophyte Bacteria 

Unlike epiphyte bacteria, endophyte bacteria is a group of bacteria that live inside your plants as well as in the soil, like Arthobracter. They help your plant fight off harsh conditions and environmental stresses by improving nutrient uptake, stress resistance, and immunity by producing antibiotics. 

Some types of endophyte bacteria even feed on pesticides and other chemical compounds, so they can help clear up your soil of such harmful chemicals. 

6. Glomus Intraradices

This is a fungi species that is known as the fungal network builder for plants. This fungus uses the tree-like structure of arbuscular organs to penetrate the root cells, promoting the exchange of sugars and nutrients between the plant and the soil. One of the most important nutrients this fungus helps with is phosphorus, so this can significantly boost your plant’s bud development process. 

7. Bacillus subtilis 

This rod-shaped microbe helps cannabis plants fight off pests and diseases and they are one of the best bacteria for improving phosphorus uptake for cannabis plants. Plus, since they can survive harsh conditions, they are an ideal soil addition for growers that live in extreme regions. 

8. Nitrosomonas Europaea

As mentioned earlier, Nitrosomonas europaea is a beneficial bacteria that is known for being one of the best at repairing old soils. If your soil is saturated with harsh chemicals or synthetic nutrients, you can use these bacteria to clean the soil. Plus, this bacteria is a terrific nitrogen fixer for cannabis plants and can go a long way in not only repairing the soil but also improving your plant’s growth. 

Adding Beneficial Microbes to Your Cannabis Soil

Adding Beneficial Microbes to Your Cannabis Soil

Adding beneficial microbes is as easy as adding any other fertilizer, but the benefits are longer lasting and much better than other soil amendments. But you still need to keep a few things in mind and take the right steps. 

But before you begin, the first step should be to prepare the environment and create the right conditions for the microbes to service. This will help you make the most out of your microscopic little friends. Here are some factors that you need to account for:

Once you have created the right conditions, you can start adding beneficial microbes to your soil. Here are some ways of adding the same. 

1. Compost Teas

One of the most popular and effective ways of adding beneficial microbes to the soil is via compost teas. You can prepare compost tea by steeping a small compost sample in water for some time. You can even purchase a compost tea product from a gardening store and add it to water if you don’t have a compost pile at home. 

Once the tea is steeped for some days, you need to strain it and add it to the soil at any stage of your plant’s life. This tea will be rich in not only beneficial organisms but also minerals and nutrients. 

2. Microbial Formulations 

If you don’t want to go through the effort of preparing a compost tea, you can simply get microbial formulations from your local horticultural store. These cannabis-focused products contain the right type and quantity of various microbes that can help cannabis plants thrive. 

All you have to do is follow the manufacturer’s instructions on the package on applying them to the soil and watch them do their magic. And don’t worry, these products are completely safe and harmless but can be a little expensive compared to compost teas. 

3. No-Till Method 

If you have been tilling your soil between harvests, you should consider not doing it anymore. Tilling aggressively works the soil and breaks the established networks of microbes within. So, if you practice progressive planting of cannabis and don’t till your soil, your plants get to grow in a medium that’s already thriving with a rich microbial ecosystem

You can combine this method with cover cropping, too, to ensure the diverse ecosystem in the soil is well-fed. Here, you need to plant plants like grass, vetches, or legumes under the later plants to foster a healthy symbiotic relationship between your cannabis, microbes, and other cover plants. 

Harmful Microbes to Be Wary Of 

Harmful Microbes to Be Wary Of 

Not all microbes are beneficial, as some microbes can be detrimental to your cannabis plants. These microbes, including some bacteria and fungi, can threaten your cannabis plant if they make the growing medium their home. Here are some of the most notorious ones.

1. Fusarium 

Fusarium is a fungus that’s considered mold, and for cannabis, mold is one of the worst things that can happen. Once this fungus takes hold, it spreads rapidly and can take over your entire plantation in a few days, causing all sorts of problems for your cannabis plant. 

2. Pythium 

Pythium is another soil-borne organism that can be harmful to cannabis plants. This fungus grows in moist soil and can take over your plant, causing symptoms like wilting and discoloration in the leaves. It’s best to avoid this by simply keeping the soil aerated and well-drained at all times. 

3. Rhizoctonia 

Rhizoctonia is also caused by excess moisture within the soil, usually due to overwatering, and sometimes, it can be introduced into the soil via insects like aphids and thrips. This infection develops dark patches on the leaves and can eventually kill your plant if you don’t eliminate it on time. 

4. Botrytis 

One of the most notorious types of fungus that can affect cannabis plants is botrytis, which is caused due to warm temperatures and high humidity, and this fungus causes the classic mold symptoms on plants like white fuzzy patches on the buds and leaves. 

Summary: Essential Microbes for Soil-Based Cannabis Plants

Soil microbes have probably existed far longer than anything on land, and they are the true forces of nature. They are what maintain life on earth, so why wouldn’t they maintain a few bushy cannabis plants? While many growers take an isolationist way of growing cannabis, you need not do that. Instead, let these incredible lifeforms help you grow your cannabis plants. 

These microbes help create a thriving environment within your soil, a symbiotic relationship between your plant and other lifeforms, which can not only benefit the plant you’re growing but also benefit the plants that follow by keeping the soil healthy, fresh, and packed with nutrients. So, what are you waiting for? Introduce some of these microscopic helpers in your cannabis soil and watch them do their magic on your cannabis plants. 



There are so many errors in this article it's pathetic. Could not even make it out of the first section labeled Bacteria. Glomus Intraradices is a Fungi not a bacteria. Mycorrhiza is not a "popular fungi species" as this so called expert writer labeled it in section 2 marked Fungi. Mycorrhiza is under which Glomus Intraradices falls not it's own distinct strain of anything. It is a term used to describe the symbiotic relationship of fungus and soil. This crap continues throughout the article. Clearly an uninformed author trying to make a quick buck. I'm ashamed of Grow Diaries for letting this junk pass through.


@archermcdaniel, hi, I had mentioned that Glomus Intradices is a fungi in the next section. Have deleted the part where I used it as an example of bacteria.

I have made other corrections too. Thanks for pointing them out.