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Mycorrhizae 101: How Fungi and Plant Symbiosis Can Help a Cannabis Grow Thrive

This article is sponsored by Hydrodynamics International.

As legislation around cannabis evolves throughout North America, backyard gardeners and professional farmers alike are growing more plants every year. This explosion of interest in cannabis cultivation has been accompanied by renewed attention about how to get the most out of cannabis crops large and small. Mycorrhizae supplements are among the tools now being put to work in both gardens and grow-ops. But what’s behind this symbiotic success story, and how does it help cannabis plants to thrive?

What Are Mycorrhizae?

Mycorrhizae are a class of fungi that thrive in symbiotic relationships with the root systems of plants. This partnership is common throughout the plant kingdom, and is often integral to the health of crops around the world. It may even have been key to the initial spread of plants on land—evidence suggests that mycorrhizal relationships date back more than 230 million years, to when plants were still working to make the transition from sea to land.

Mycorrhizae comprises many strains and species of fungus that thrive in symbiosis with plants

Morel mushrooms are the fruiting bodies of fungi in the genus Morchella, many species of which are mycorrhizae. (tomasztc/iStock)

Mycorrhizae may have made that transition more seamless because these fungi make life just a little easier for plants. For instance, mycorrhizae that pair with plants like cannabis penetrate the root, sharing in its nutrients. It’s in the fungi’s interest, then, to make sure the plant they’re partnered with is getting as many nutrients as it can—the better the plant does, the more healthy and successful its fungal partner will be.


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Benefits of Mycorrhizae

When mycorrhizae colonize a plant root, they proceed to branch out into the soil around it. “You can almost envision mycorrhizae as a series of secondary roots, coming off of the plant root,” says Jason Steinman, production manager at the plant nutrient supplier Hydrodynamics International. “Except those secondary roots are actually strands of fungus.”


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Those additional branches serve an important purpose, expanding the surface area and reach of a partner plant’s root system. More surface area means that the roots are in contact with more soil, more water, and more nutrients, so that they can make the most of the resources that surround them. The result is that plants colonized with mycorrhizal fungi have been found to be more resistant to factors like stress and drought.

mycorrhizae fungus help plant roots absorb nutrients and minerals from soil.

Mycorrhizae can supplement the root systems of plants from cannabis clones to tomato starts, making them more resistant to stress. (Phoenixns/iStock)

“If you have plants that are in a drought scenario, you will see leaves that are drooping or falling off, and you’ll eventually see the whole plant die,” says Steinman. “In plants treated with mycorrhizae, you’ll see that much more slowly than in their untreated counterparts. And that’s because before the drought, they were able to make the most of the resources in their environment, so they’re more prepared for lean times.”


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It’s not just expansion that improves the health of plants that have mycorrhizal sidekicks, though. Some mycorrhizae can also help to break down nutrients found in soil, such as phosphates. That makes it easier for their partner plant to absorb those nutrients, the same way cutting up a meal into smaller bites makes it easier for us to eat. The presence of mycorrhizae can even help ward off plant pathogens like molds, making it possible to fight fungi with fungi.

Introducing Mycorrhizae to a Cannabis Grow

Chances are, whatever soil you’re growing in already has some mycorrhizae in it. But just because these fungi are present in a growing medium doesn’t mean they’re making the plants in it healthier. Mycorrhizae spores—the fungal answer to seeds—need to come into direct contact with a plant’s roots to colonize them. And since the spores are fairly large, they don’t travel easily through soil.


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That’s where mycorrhizae-rich supplements like Clonex Root Maximizer can come in handy. In outdoor grows where plants are susceptible to the whims of weather, a thriving mycorrhizae population can render plants hardy enough to make it through trying times. Even in indoor growing operations where conditions are more tightly controlled and monitored, mycorrhizae can provide an “insurance policy” of sorts against unforeseen malfunctions.

Mycorrhizae can help plants in your cannabis garden better resist stressors like drought. (Yarygin/iStock)

Depending on a grower’s methods, mycorrhizae may be more than an insurance policy. In organic grows, for instance, these fungi are instrumental in breaking down organic material into small enough parts that it can be effectively put to use by cannabis and other crops.

Whether you’re planting row after row of flowers or a couple plants for personal use (and consult the laws in your area on that front, of course), mycorrhizae can give your cannabis crop a boost. As events like droughts become increasingly common, this little-known partnership between fungus and plant could be the difference between a successful growing season and hoping for better luck next year.

  • Jonathan King

    The caption for the morel photo needs some careful revision. Fruiting mushrooms are not themselves mycorrhizae. Nor are they in any sense ‘strains.’

  • Turner Kayston

    In listening to Dennis McKenna (Terrance’s brother), on a Joe Rogan podcast episode (on YouTube), he had suggested reading the book by Stephen Harrod Buhner: “Plant Intelligence and the Imaginal Realm: Beyond the Doors of Perception into the Dreaming of Earth” – ISBN: 1591431352

    One of Jeremy Narby’s books, Intelligence in Nature also complemented this book really well I found.

    To better understand how fascinating this really is, one should read one of Stephen’s books (now on my 5th of his). It has drastically augmented my views and understanding of many things. I’m sure others would just as much enjoy reading it as I did.

    I also highly recommend reading it to better understand the Gaia theory, by James Lovelock and Lynn Margulis.

    And to know a lot more about fungi in technical detail – Paul Stamets is the one I would say.

    • PatrickMonkRn

      Agree on Stamets.

  • Jeff Lowenfels

    it is mycorrhizal fungi…they form a mycorrhizae with the roots.
    see my book: Teaming With Fungi…only one mycorrhizal fungi pairs with cannabis

    • Cal

      Sharing is the way.

  • Cal

    Another misleading article/media piece from leafy. Anecdotal I know – but I really haven’t noticed much difference between harvesting milky and amber.

    • DCBC

      If harvested early with mostly clear trichs the cannabis should have more of a high. More mature milky crystals will turn amber as they cure often and this cannabis flowered a little longer will have more medicinal effect and a little more of a stone. It will happen naturally over curing as well and depending how you cure also. Natural Decarboxylation converting THCA to THC and CBN to CBD and all the good things most people miss because they smoked it before it even cured.. Legalization is the perfect opportunity for us all to take our time growing our cannabis and share it.

      • E.L. Bl/Du

        If you EVER tested your weed you would know, MILKY is when the THC is the highest concentration. After that, when they start to turn amber, the THC decreases and CBN Increases. (COUCH EFFECT) Most ppl prefer a combo of both, which is when they are at about 10% amber. It all depends on whether you want a cerebral or couch effect. So its a PERSONAL preference WHEN you harvest. They do NOT continue to mature after picking. They just continue to degrade, like anything that is picked from a plant. I think you are confusing “more of a stone” with More CBN in your weed. At least thats what I interpreted from what you wrote.
        The mycorrhiza is important to put in the soil when they go in the ground and after ANY spraying. Otherwise only your pocketbook knows for sure. This is one of those garden myths like using “superthrive” or B vitamins will reduce transplant shock. MYTH! Plants cannot utilize B vitamins. Only your pocketbook knows the difference.

        • DCBC

          I don’t have time to argue with “most ppl Prefer”, bullshit. I don’t got my point also most ppl grow junk.

        • DCBC

          Also my friends and myself test it everyday and it’s some of the best on the planet with out all your fancy gear and expensive labs. Dispensary cannabis doesn’t compare. There’s a whole lot more to the active chemicals and curing than i have time to get into.

          • E.L. Bl/Du

            I dont grow with fancy gear at all, I grow outdoor and some of the BEST ORGANIC weed on earth also. PPL from ALL OVER come to the EMERALD TRIANGLE to get the weed from here. I wont even go into dispensary crap. You have NO NEED to get nasty or arguementative, Im talking LAB RESULTS and you CANT ARGUE WITH THAT anyway. I agree most ppl grow shit and I cant even smoke it. Only a few ppl that Iknow, and prob you are the same. Theres allot of idiots out there I can surely agree with you on that too. We tested ours one year to shut the arguement off. Indoor vs outdoor, more thc and when, all the micro bullshit etc bla bla all the rookie shit that ppl seem to be experts about and totally missing the point.. I wanted to know for sure so we tested it. THats is all I was saying DCBC. Im happy you grow good stuff, and dont need allot of fancy stuff that is NOT necessary when you know whats up..RIGHT? Most do not. I just wanted proof so we paid to test one year to find out for sure.

          • DCBC

            My Point is that early harvested clear resin might test higher in the lab, but there’s way more to it than that. Also I’ve been growing outdoors for over 30 years that argument i’m sure will never be off but you can’t compete with SUN AND MOONLIGHT I’ll just say that (it’s just most people fail outdoors). Seems a lot of people have the wrong idea or some odd preferences. Ever notice on seed bank sites they will say the commercials grow this strain for 8 weeks but the true flavor and high come out after 9-10. When I started growing, the plants I had at the time were a stain iv’e never seen anything close to resembling it. It took 3 1/2 months to flower and incredible a joint tasted like you had rolled pure hash. This is when hydro started to get popular and then everyone was about speed, Speed is imposed when it’s illegal and in demand so much and had to be hidden. Years of breeding out the fastest strains and indoor maniplulations and now seed breeders selling mostly feminized seed and auto flower.Funny how they claim it’s the rage and all that but their almost out of regular seeds and have raised the price of them. Also notice that i don’t know maybe 80-90% of the seeds on the market flower between 7-11 weeks, that never used to be. I am just trying to help people and think cannabis should be decriminalized and shouldn’t be this huge cash grab and people selling info that’s available for free it’s stupid. Anyhow how you like you crystal is a matter of preference but i am saying that degradation is the wrong word for something that is going to cure for a few months to become better. Myself and others have pulled out hash several years later only to find it mellower and way more potent than when it was made. Clear crystals give me a clear high that is very short, but cured crystals from a mature plant DON”T NECESSARILY GIVE YOU COUCHLOCK – it depends on the strain. I’m sorry i’m not a writer and i don’t have time to explain everything.

  • RHBCO2

    Just banned by the fda. All cbd products