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All Things Garden,  Cannabis,  Compost

The Benefits of Using Mycorrhizae in the Garden

When it comes to maintaining a healthy and productive organic garden, there is a lot more happening than meets the eye! In addition to the obvious elements (sun, soil, plants, and water) there is a dynamic network of living things that work synergistically within the soil to help plants thrive. Critters and microscopic organisms decompose organic matter, transform nutrients and minerals, and create various reactions that contribute to overall soil fertility. One of the key players in this essential ‘soil food web’ is mycorrhizae – something we routinely add to our garden soil!  

Read along to learn all about mycorrhizae. This article will cover what it is, how to use it in the garden, and most importantly, the benefits mycorrhizae provides plants. Spoiler alert: it will help your plants grow larger and healthier than ever! We’ve been using mycorrhizae in our garden for many years now, ever since Aaron’s dad turned us on to it. Even if you’re not a hardcore soil nerd, I bet you’ll find this information fascinating!



What is Mycorrhizae?


When you break it down, the word “mycor-rhiza” literally means “fungus-root”. Mycorrhizae is a form of beneficial fungus; one that cannot live without being connected to plant roots. Yet the connection isn’t just about helping the fungi survive! Together, they form a symbiotic relationship that offers outstanding benefits to the host plant as well, such as increased nutrient uptake, added resilience to disease or stress, and higher yields. We’ll talk about the benefits of mycorrhizae in more detail below. 

Over 95% of the world’s plants form beneficial associations with mycorrhizal fungi. Some types colonize on the surface of plant roots only, known as ecto-mycorrhizae. These fungi bond with select woody trees like conifers, hazelnuts, and pecans. In contrast, endo-mycorrhizae penetrate the root cells to become a part of the root system itself. They’re also far more prevalent. 80 to 85% of edible garden crops, fruit trees, flowers, herbaceous plants, and ornamentals make associations with endo-mycorrhizae, so that’s the type you’ll find in mycorrhizal products made for home gardens.


A pine seedling rootball is shown from the soil below. Its rootball is large and expansive, more than 3 or 4 times the height of the seedling itself.
A pine seedling roots flush with mycorrhizal fungi, allowing the plant to obtain nutrients from a bigger volume of soil. Image from David Read, author of Mycorrhizal Symbiosis.


What does mycorrhizae do?


After colonizing plant roots, mycorrhizae acts like an extension of the plant’s root system and can increase the absorptive surface area of roots by up to 700 times! Imagine millions of little straws and fingers now available to more deeply and efficiently access valuable resources within the soil – including water, nutrients, and even air.

Furthermore, mycorrhizal fungi release enzymes that help to ‘unlock’ and dissolve essential nutrients within the soil. That reaction makes those nutrients more bioavailable for plants to easily utilize, including phosphorus, iron, and other minerals. Keep in mind that mycorrhizae isn’t a fertilizer however, so it will only help the plant use nutrients that are present in the soil (albeit better) – so you still need to routinely amend soil with compost and organic fertilizers. Last but not least, mycorrhizal fungi form intricate webs that capture and store excess nutrients in the soil for later use. This enhances soil fertility long-term.

So, what do the fungi get out of all this good samaritan work? The answer is food. As mycorrhizae helps plants to better utilize nutrients for growth and photosynthesis above-ground, the plants send sugars back down to their roots to nourish the fungi. Everyone wins! 


A diagram illustration showing a mushroom growing in the soil next to a tree and its roots. Below the soil line shows the roots from the fungus exchanging water and mineral nutrients to the tree for photosynthesis products in the form of carbohydrates for the fungus.


Benefits of Using Mycorrhizae


Due to the mutually beneficial exchanges that occur between mycorrhizal fungi and plant roots (e.g. increased nutrient uptake), studies show that mycorrhizae offers plants the following benefits:

  • Promotes larger plant growth and healthier, deeper dark green foliage.
  • Leads to greater flower and fruit production (more and/or larger). For farmers, higher yields also means higher income. 
  • Enhanced resilience to stress, heat, and other environmental changes.
  • Improved water uptake, leading to increased drought-resistance and less water demand for the plant. 
  • Lessens the risk of transplant shock, such as when planting new trees or moving indoor-raised seedlings outside.
  • Increases plant disease resistance by promoting overall improved plant health. Also, when plant roots are colonized or coated with mycorrhizal fungi, it limits access to the roots by other harmful pests, fungi, or diseases. For instance, studies show that plant roots colonized by mycorrhizae have added protection against parasitic root-knot nematodes and root-chewing insects!
  • Reduces the need for fertilizer inputs (and associated costs).
  • Decreases the accumulation and residual levels of toxic contaminants in crops, such as persistent organic pollutants (POPs), which plants typically readily absorb in their roots and tissues.
  • Naturally improves soil structure, fertility, and promotes a healthy living soil food web.


Sound too good to be true? Check out the photos of side-by-side grow trials below. The plants were treated exactly the same, with the exception of one being inoculated with Plant Success mycorrhizae – the larger plant in every photo!


A person on each side of the image is holding a small fabric pot with a basil plant in each pot. The plant on the left is almost twice the height and width of the plant on the right.
Basil inoculated with mycorrhizae (left) versus not
Two marigold plants are shown, each in its own fabric grow bag. The plant on the left is much larger, almost twice the size in height and width and more flowers than the one on the right.
Marigolds inoculated with mycorrhizae (left) versus not
A two image collage, the first image shows two eggplant plants, both in its own fabric grow bag and the plant on the right is twice the other plants height and width with more flowers. The second image shows two bean plants, each in its own grow bag. The plant on the right is more than twice the size and width of the other plant with many more flowers as well.
Eggplant and beans inoculated with mycorrhizae (right) versus not. Side-by-side grow trial images courtesy of Plant Success Organics


Plants that Benefit from Mycorrhizae


Nearly all plant species benefit from mycorrhizal associations! Mycorrhizae’s ability to make phosphorus more bioavailable is especially valuable for flowering and fruiting horticultural crops like tomatoes, peppers, squash, cucumbers, eggplant, beans, cannabis, berries, fruit trees, and more. It will also help your ornamental flowers and shrubs thrive, including both annuals and perennials. Beyond flowers and fruit, mycorrhizae promotes more vigorous growth in herbs, lettuce, potatoes, carrots, asparagus, garlic, and onions as well. 

The brassica plant family is among the small number of plants that do not form mycorrhizal associations. Meaning, your broccoli, cabbage, turnips or radishes will not benefit from mycorrhizae – but it also will not harm them!


An early summer harvest displayed in an artistic manner. Green and yellow summer squash, yellow and red tomatoes, apples, rosemary sprigs, garlic bulbs, various varieties of green beans, kale leaves, chard leaves, calendula flowers, avocados, and chiles make up the assortment that is compiled on a large, flat wooden board.
A late spring harvest from our garden. Nearly every one of these plants forms beneficial mycorrhizal associations to boost growth – including apples, tomatoes, squash, peppers, beans, avocados, berries, garlic, flowers, herbs, and more (with the exception of the kale, a member of the brassica family)


How to Use Mycorrhizae in the Garden


Mycorrhizae should naturally be present in healthy, organic soil to some degree. Using organic gardening techniques such as compost, compost teas, cover crops, mulch, or no-till methods all foster a rich and diverse living soil food web! Harsh chemical fertilizers, pesticides and herbicides make soil sterile and inhospitable to all living things – including the good guys. 

However, it can take a long time to develop a robust population of mycorrhizal fungi in the average home garden, especially in newly-established gardens. Also, the native populations of fungi can vary drastically from season to season or bed to bed. Therefore, the best way to guarantee your plants reap the rewards of beneficial fungi is to inoculate your garden with mycorrhizae

  • One option is to sprinkle granular mycorrhizae directly on the root ball or in the planting hole when transplanting new plants into the garden or into a larger container. See the photos below. Water the soil well after application and planting!
  • Another awesome way to add mycorrhizae to soil is to mix up a water-soluble mycorrhizae product and water it in. You can do this any time – be it right after transplanting, or to boost established plants later (e.g. fruit trees or shrubs). If you direct-sow seeds right in your garden (such as beans, peas, or garlic), wait to water them with mycorrhizae until they’re at least several weeks old and have developed a couple sets of ‘true leaves’ – which means they’ll have some roots developed by then too!
  • No matter which method you choose, keep in mind the fungi need to come in direct contact with living roots as soon as possible in order to survive. For this reason, always apply mycorrhizae immediately around the plant’s root system. They can’t travel in search of roots. 
  • Again, remember that mycorrhizae isn’t a fertilizer – it simply helps plants make better use of nutrients in the soil. So, be sure to routinely amend your garden with compost and mild, organic fertilizer too!


Related: Transplanting Seedlings Outside: Tips for Success and How to Amend & Fertilize Garden Beds Between Seasons



A 1/2 teaspoon measurement is full of granular mycorrhizae, below lies a tomato seedling rootball, a trowel, and a garden glove atop a bed of garden soil.
Option 1: Add granular mycorrhizae around the inside walls or bottom of a planting hole, such as when transplanting new seedlings into a garden bed, or planting fruit trees and shrubs.
A tomato seedlings rootball is shown that has been sprinkled with granular mycorrhizae that resembles crushed eggshells. The roots are white and fibrous.
Option 2: Sprinkle granular mycorrhizae directly on to the root ball.
A watering can is being used to water a tomato seedling transplant in a raised garden bed with water soluble mycorrhizae. The background is the border of the yard which contains nasturtium, salvia, fig tree, and the lower limbs and leafs from an avocado tree.
And option 3: Use a water-soluble mycorrhizal inoculant to water freshly transplanted plants (or established plants).


Our Favorite Mycorrhizal Inoculants


There are a number of mycorrhizal products available on the market. We personally love and use the granular and water-soluble mycorrhizae inoculants from Plant Success Organics. They’re one of the most established and reputable brands, and offer high-quality, effective products that are OMRI-certified for organic gardening. I also love that they add beneficial bacteria to their products to further support the soil food web. Bacteria play a similarly significant role in plant health. In a nutshell, think of them as pre- and probiotics for roots, and roots as the gastrointestinal system of plants. There is a direct link between the human gut, probiotics, and overall improved health outcomes – and plants are no different! (Use code “DEANNACAT” to save 15% on the Plant Success website)


DeannaCat is holding a package of water soluble mycorrhizae from Plant Success Organics. Beyond lies a wheel barrow with an uprooted small kumquat tree inside as well as an arch beyond that with dense green passion fruit vines covering it. This leads to an area that is lush with lavender, vines, and rosemary bushes.
A two part image collage, the first image shows a recently uprooted small kumquat tree that is laying in a wheel barrow with soil below it. It fibrous roots are exposed with little to no dirt making up the root ball. The second image shows the kumquat after it has been transplanted into a 10 gallon plastic terra cotta color pot. A watering can is sticking into the frame from the edges of the image, watering the transplanted tree with water soluble mycorrhizae.
We recently dug up a kumquat tree that was not thriving in its current location in the garden. Unsure of where we want to plant it yet, we opted to re-home it into a large pot for now. To minimize the transplant shock and give the tree a boost, we thoroughly watered it with Plant Success water-soluble mycorrhizae after the move. Several weeks later, it looks great and hasn’t dropped a single leaf!


Can mycorrhizae be harmful to plants?  


There is virtually zero risk of harming plants by using mycorrhizal fungi products in your garden, especially if you follow the application directions provided. Even then, it is difficult to ‘overdo it’. Mycorrhizae is not a fertilizer and therefore cannot “burn” your plants like a high-nitrogen product might. If excess beneficial fungi are added to the soil beyond what can form associations with plant roots, they will simply die. 



Where does mycorrhizal fungi come from? 


The relationship with mycorrhizae and plants can be traced back millions of years. According to genetic studies, prehistoric ocean-dwelling plants began to slowly migrate onto land approximately 700 million years ago. They had very minimal root systems, and the soil was tough and unforgiving. Over time, plants partnered up with the fungi that already ruled the land. They evolved together to improve soil: plants developed more complex root systems, nutrient cycles became established, organic matter grew (and decomposed), and terrestrial life as we know it flourished. 

Modern mycorrhizal products are created at facilities that ‘farm’ or breed select strains of naturally-occurring beneficial mycorrhizal fungi. Mushrooms and fungi reproduce by releasing spores. Those spores are then collected, turned into mycorrhizal inoculant products, and sold with the spores in a dormant state. Later, once they’re added to your soil and come in contact with living plant roots and moisture, the spores will germinate and become one with the roots!


A cylindrical container of Plant Success Organics granular mycorrhizae sit in the foreground on the edge of a garden bed. Beyond lies two 6 cell packs of basil seedlings with two large tomato seedlings towering over them from behind. The backdrop is dense green with salvia, nasturtium, as well as a magnolia tree, a fig tree, and avocado tree.
Transplanting day for tomatoes, basil, flowers and more – with a side of mycorrhizal fungi.


Remember: feed the soil, not the plant!


Organic gardening is all about building and maintaining rich healthy soil as opposed to simply fertilizing plants, and it’s safe to say that mycorrhizae are an essential part of a complete soil ecosystem! I hope you enjoyed this mycorrhizae 101 lesson and learned something new. Are you excited to inoculate your garden with mycorrhizae too? Please feel free to ask questions in the comments below, and share this article if you found it valuable. Last but not least, we want to thank Plant Success Organics for sponsoring this post. And thanks to you all for tuning in!


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DeannaCat signature, keep on growing

30 Comments

  • Sara

    If I fill a 1 gallon watering can with 1tsp of the Mycorrhizae how much should I apply to each planted plant? For ex. would you recommend 5 sec each or full gallon for each plant? I haven’t found any instructions like this for this product. Thanks in advanced!!

    • Aaron (Mr. DeannaCat)

      Hi Sara, we would likely just give each plant a small amount such as you mentioned (about 5 seconds). You could water in more but introducing the fungi to the plants root zone in any amount will help start a colonization of the root zone. Also, if you are watering an entire raised bed, your watering will be spread out fairly evenly across your soil and the root zones of all of the plants. Good luck and happy gardening!

  • Gene @The California Table

    wow, thanks for the great primer on the benefits and how-tos for mycorrhizae! I’ve ordered the starter kit from Plant Succes and I am gladly anticipating bringing these beneficials into our “permaculture paradise” :–) I hope I am thinking of this correctly (please advise if I am not); my thinking is that our new raised bed are filled with kitchen waste and trucked in topsoil and compost so there may not be any mycorrhizae available. So applying with the Plant Success products could be a big help to our new garden plants. Thanks again for the helpful information! Gene

    • Aaron (Mr. DeannaCat)

      You’re right on track Gene, your soil may or may not have any mycorrhizae available but adding additional mycorrhizae will help out your garden tremendously and I think you will see the results for yourself this year. Your permaculture paradise will appreciate the mycorrhizae and compost tea and you may be in for your best garden year yet!

  • Emily

    Do you know anything about the myco chum microbe food that Plant Success sells in the bundle with this? I can’t find much about how to use it and what it’s best for.

    • Aaron (Mr. DeannaCat)

      Hello Emily, Myco Chum is used as a food for the microbes and fungi, it’s made with molasses, kelp, and fish hydrolysate. It essentially helps the plants by giving more food and “sugar” to the microbes which in turn helps the plant by creating more roots which can better absorb water and nutrients. Hope that helps and let us know if you needed anything else cleared up.

  • Deanna

    Quick question on the mycorrhizae article. After transplanting your babies how often do you water with the water soluble version? Do you keep applying?
    Thanks!

    • Aaron (Mr. DeannaCat)

      Hello Deanna, we usually only apply the mycorrhizae one time at the beginning as once it has a population established it is good to go from there. Good luck and happy gardening!

      • Caroline

        Hi! Do these products have a shelf life and a hould they be stored at a certain temperature? Thanks for the great article!

        • Aaron (Mr. DeannaCat)

          Hi Caroline, I am sure they have a shelf life but it is probably a number of years stored at or around room temperature. Most things are best to keep out of extreme heat or cold, thanks for reading and good luck!

        • Aaron (Mr. DeannaCat)

          Hi Anthony, I know the roots can get crazy when using a hydroponic garden but yes I think your plants would benefit greatly. Just be sure to inoculate the roots directly before you add them to your system to be sure that the roots come in direct contact with the mycorrhizae. Hope that helps and let us know how it works out.

    • Leslie

      I appreciate this information. Do you know how extreme temperatures affect mycorrhizae in the soil? I the soil freezes in a cold winter will it recover the following spring? Also, is Mycorrhizae you use the same as that of oyster or wine cap mushrooms? Will wine cap spawn work in the same manner or should I use both? Thanks!

      • Aaron (Mr. DeannaCat)

        Hi Leslie, I tried to find information through a few scholarly articles and it seems the mycorrhizae hyphae activity will slow down during freezing conditions, if there are no roots to form a relationship with, it may cease all together. With our garden beds, as the plants change throughout the seasons, we usually end up reapplying on a yearly to bi yearly basis with an emphasis on flowering summer crops. The mycorrhizae we use has mycorrhizae, bacteria, and trichoderma and I am not sure of the exact origins of the fungus. Here is a link to the ingredients of the Plant Success Organics granular one we use. I believe mycorrhizae is most effective when there are at least 3 or 4 different ones available. Hope that helps and good luck!

  • Rachel

    Thank you for this post! Just wondering if you have any suggestions for the best place to buy this stuff in Canada?

    • Aaron (Mr. DeannaCat)

      Hello Rachel, I am not sure where in Canada might sell Plant Success Organics but Arbico Organics is one US based company that has International shipping although they will only do International orders via phone. Gardenerspantry.ca, amazon.ca, and indoorgrowingcanada are online retailers where they have some brand of mycorrhizae or another. Hope that helps and good luck!

  • Jocelyn

    Thanks so much for sharing all about mycorrhizal fungi! I’m currently reading the book Hidden Life of Trees and the author talks in-depth about this powerful symbiotic relationship between fungi and trees. I had no idea though I could ADD this to my garden beds and fruit trees! After reading your article I promptly went to the website you suggested and purchased both the granular and water soluble mycorrhizae products. I’m SO excited to incorporate mycorrhizae into my garden!
    Thanks again for providing yet another informative and inspiring article! 💚

  • Phillip

    Really enjoy your posts. Thank you for doing this. Does this fungus help prevent nematodes from attacking tomato, okra, and peppers?9

    • Aaron (Mr. DeannaCat)

      Hello Phillip, thank you for your support! Mycorrhizae can and does protect plants from root nematodes by reducing their population. Good luck and happy gardening!

  • Tonya Flowers

    Deanna,

    Thank you so much for posting this article!! I have been looking for a good source of mycos for direct application and instantly bought this as soon as I saw it! I shared your article with family and friends to spread the knowledge. Thank you for everything you are doing for our community! Your articles and videos have helped me establish everything I have created so far.

  • Emily

    Thanks for this in-depth article, I’m going to share it with some gardening friends! I got myself some mycorrhizae to add to my garden this year!! I can’t wait to see how my plants thrive.

  • Krissy Kaufman

    Can you incorporate the granules into soil when direct seeding things like beans? Or do you just wait and water with a water soluble solution?

    • DeannaCat

      Hi Krissy – Good question! Since the fungi need to attach to living roots, it won’t do much to use them for seeds (or bulbs/rhizomes) that haven’t yet grown roots. So for those types of things, you’d want to apply the water soluble option after they sprout and begin to grow. Thanks for reading!

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