Mycorrhizal root tips (image by Thergathon)

    The word mycorrhizae (pronounced My-cor-rye-zay) refers to a group of fungi which form a mutually beneficial relationship with many plants. These fungi grow either inside of a plant’s roots or attach to the surface of a root. The fungi benefits from the plant’s food and nutrients and in turn send their hyphae (like small roots) out into the surrounding soil to absorb nutrients and water.

    So, mycorrhizae actually enhance a plant’s ability to take up nutrients and water. Because of this, research has shown that the presence of mycorrhizae also help plants deal with drought and some diseases. Approximately 95% of the world’s plants have some form of mycorrhizal dependence. As far as growing is concerned, in many cases, increased root and top growth occurs when plants are treated with mycorrhizae. These benefits are not always evident, especially on short term crops, unless the crop is stressed or planted into a landscape where water and nutrients are less available.


    462Sunshine Advanced MIX 4 2.2 cuft RESILIENCE front WEBThere are two main groups of mycorrhizae – Ectomycorrhizae and Endomycorrhizae. Both groups are specific in what plant types they will work with. Ectomycorrhizae forms relationships with birch, oak, spruce, pine and fir, but is not important to most greenhouse growers since the above plant types are not typical greenhouse crops.

    The second group of mycorrhizae is endomycorrhizae which are also known as vesicular-arbuscular mycorrhizae or VAM. Roughly, 80% of all the plants in the world form associations with endomycorrhizae, as does nearly every greenhouse plant. So, this is the group of mycorrhizae that is most important to greenhouse growers, and the everyday grower. It is the one that you want.


    It is not difficult to create a good environment for endomycorrhizal (VAM) colonies; all that’s needed is a plant that forms a relationship with VAM. After that, the primary factor is the amount of inorganic phosphorus in your growing system. Since the relationship between plant and fungi evolved to help the plants access low levels of phosphorus in the soil, mycorrhizae do not grow and colonize roots when the phosphorus level is high. Phosphorus levels above 10 ppm in the soil solution will negatively impact the growth and establishment of mycorrhizae. A high phosphorus level does not kill the mycorrhizae, it just creates an environment in which the mycorrhizae do not germinate and grow, and this renders them ineffective. As a grower, you should use low phosphorus feeds for the first 30 days to allow the mycorrhizae to grow.

    Typical lime rates and medium pH levels of Sunshine Advanced grow mixes do not have a significant positive or negative effect on the growth and colonization of mycorrhizae.

    Chemical fungicides should be avoided especially at the start of production and until enough time has elapsed to allow root colonization to occur.


    The Sun Gro technical team has found excellent colonization results when mycorrhizae is added to Sunshine Advanced grow mixes. Organic fertilizers release their nutrients slowly over time so the levels of phosphorus remain within a tolerable range for good mycorrhizal growth and colonization. Since we wish to supply our customers with the best performance, we are offering Sunshine Advanced grow mixes with mycorrhizae.


    Other media products in the market offer single species of endomycorrhizae or offer a blend of endo and ecto mycorrhizae. Sunshine Advanced grow mix amended with mycorrhizae use a blend of endo species designed to enhance colonization under a wide range of growing conditions. We do not add ectomycorrhizae since they provide no benefit to most crops.



    1. James

      I have started using and testing Advanced Mix #4. I have done three runs of your product and the only issue until recently was my pots didn’t need watering for approximately five days. Now I have run into mold being a problem.

      We break up and store your largest bricks into garbage cans with the excess leftover brick covered with a spent bag. They can sit for anywhere from 1-2 weeks before we need to use this ‘dirt’. We have gone through approximately two dozen of your largest bricks and have had no issues with storage until now.

      We opened one of the cans and it had mold growing on the top. We then reopened the three quarter unused brick to break-up and it had mold growing on it too.

      Do you have any known reason as to why this mold issue would start at this time? Unfortunately if mold is going to be an issue we will have to discontinue your product and go back to making our own ‘dirt’.

      Thanks for your response in advance.

    2. admin

      Hi James,

      Any moist, exposed media has potential to develop mold, especially if enclosed in a warm plastic container that can’t breathe. The same goes for an opened bag of media. Airborne fungal spores are everywhere and in greater densities at different times of the year. It doesn’t matter what kind of mix you use. And once mold proliferates, it can become difficult to sanitize the container.

      We suggest opening your bricks upon arrival and storing them in well-aerated containers in a cool, dry place, like an air-conditioned head house. Choose bins or hoppers that allow light (UV light dissuades fungal growth), with broad, somewhat open tops that encourage aeration (Rubbermaid makes some really good storage bins). We do not recommend pasteurizing the mix, because all SSA mixes are myco-active and contain active beneficial fungi. Let us know if this helps!

      Cheers and Happy Growing!

    3. Yolanda Lopez

      I planted three varieties of pepper seeds in Vigoro All Purpose potting mix. Several weeks later I transplanted most of the bare root seedlings into individual containers (clear new plastic cups with holes drilled in the bottom) using Sunshine Rain Forest blend soil. It has been at least four weeks since transplanting and the plants in Sunshine mix appear stunted and lighter in color in comparison to those left in the Vigro mix. All plants are growing in the same conditions outdoors and treated the same. The only difference is the soil. There are no pests on the plants either.

    4. Sunshine Advanced

      Hi Yolanda,

      There are a few factors that could be causing the problem you see as stunted growth.

      1) The fertilizer in SSA Rainforest Blend is organic and just a starter formula, which allows plants to become easily established in their new pots. We recommend fertilizing plants growing in this mix 7 to 14 days after transplanting. An all-purpose, water soluble fertilizer would be best.
      2) Vigoro potting mix has an added slow-release chemical fertilizer that continuously feeds the plants for 2 – 6 months. It is not an organic fertilizer but is a synthetic granule or prill.
      3) SSA Rainforest Blend is a consistently produced and formulated, well-drained, high bark mix suitable for large containers grown outdoors. Putting this product into a plastic cup may enhance the properties of the bark (i.e. leaching nitrogen from plants in small containers). Normally transplants grown in SSA Rainforest Blend are at least 6 – 12″ tall and well-developed with three or four nodes with true leaves. Plants of this age are better able to grab the nutrients from a mix and are generally grown in larger containers.
      4) Vigoro potting mix is manufactured by different companies, hence you do not have consistency from one bag to the next. The product you bought may have less bark and be a finer medium with different types of compost better suited to smaller plants.

      We recommend that you upgrade and feed your plants grown in SSA Rainforest Blend with a water soluble fertilizer, such as 20-10-20, at the regular recommended rate. Let us know the results, and happy growing!