Q. I already use Trichoderma. Are mycorrhizal fungi any
Both are beneficial fungi found naturally in soil. Trichoderma
are more for cycling nutrients in the soil and providing protection
against soil pests (but you will seldom find it labeled as a pest
control) while mycorrhizal fungi help more with nutrient and water
uptake and increased root growth. Both combined will promote a very
healthy root system overall.The two work together well. Trichoderma
help make nutrients soluble. Mycorrhizal fungi can actually take
the nutrients up and translocate them into the plant.
Q. How do I successfully introduce and propagate mycorrhizal
fungi in my hydroponic garden?
Mycorrhizal fungi can be mixed directly with soil-less media or
added to the nutrient solution directly just like any regular
powder supplement. There is a myth that you cannot use mycorrhizal
fungi with synthetic / mineral-based nutrients, but this is not
true. Mycorrhizal fungi can be used with soil, hydroponics and
cuttings. The key benefits in hydroponics are extended root systems
(which naturally lead to an increase in yield), not to mention
protection against root zone pests and diseases. Imagine miles of
mycorrhizae hyphae exploring the nutrient resources. Mycorrhizal
fungi cause roots to branch and form more fine feeder roots that
can go after nutrients and minerals.
Q. Should I feed mycorrhizae carbs? (e.g. molasses?)
Molasses and other carbs are good for feeding bacteria and other
types of fungi. But you don't need to feed the mycorrhizae. That's
missing the point. The plant feeds them! It's the exudates from the
plant roots that cause the mycorrhizal propagules to germinate.
(There are synthetic compounds that cause the mycorrhizae to
germinate but they are unnatural, expensive and not commonly
available.) You are better off adding products which contain humic
acids (organic growers can use high quality organic inputs such as
North Atlantic sea kelp) to promote more root exudates (food for
Q. What hydroponic growth media do mycorrhizae prefer?
Mycorrhizal fungi can create mycelial networks in soil, coco
coir, rockwool and many other inert growth media. They can even
survive in a totally aqueous environment, as long as it is properly
aerated, but they will not replicate. Mycorrhizae will grow and
increase in biomass only once they are attached to a plant
Q. What about mycorrhizal fungi and high phosphorus
Mycorrhizae fungi spores 'sleep' while levels of phosphorus are
high (above 70ppm). They only awaken when levels drop lower than
this. This is another reason to establish your mycorrhizae as early
on in the plant's development cycle as possible.
Q. What conditions do mycorrhizal fungi prefer?
Temperature: around 68-73°F is ideal but
mycorrhizae can also help your plants tolerate occasional temp
Moisture: mycorrhizal fungi like to have a good
air/water mix to thrive. Too moist or too dry is not ideal. Once
again, they will help the plant tolerate any extremes that
pH: it depends on the mycorrhizae species but
generally they thrive in 5.5-7.5. Some can tolerate acidic
conditions better than others while some like alkaline better than
others. Look for products that are made from a blend of different
species in order to create a healthy mycorrhizae population that
will thrive in varying pH conditions.
Q. What conditions should be avoided?
Very high temperatures. (135- 140°F will definitely start
killing them off but then, at those temperatures, the happiness of
your fungi is the least of your problems!) The less chlorine your
water contains, the better for both fungi and plants too. However,
typical levels of chlorine from municipal supplies should not cause
Q. When should I start using mycorrhizal fungi?
As soon as possible! It takes less mycorrhizae to colonize a
juvenile plant than a larger one. Commercial growers have negated
the cost of mycorrhizal fungi with their increased seed germination
rates. It takes a couple of weeks to form on the roots after the
first inoculation so get the process started right at the seedling
/ cutting stage. The trick is to introduce the mycorrhizal fungi
spores as early as possible to give them time to establish
themselves. This is particularly important if you are growing
Q. Do mycorrhizal fungi need to be reintroduced on a regular
basis? Do I need to add it more frequently than once with every
Best performance is achieved with numerous applications
throughout the growth cycle. You can't really overdo mycorrhizae.
If there are more roots producing more exudates it will probably
help to add more mycorrhizae. But don't bother any later than 2-3
weeks before harvest. It's a waste of time. Your mycelial network
should already be established. It won't do any harm to keep using
it (and often the instructions on the mycorrhizae product will
encourage you to!), but you're just wasting your money! Adding it
with every nutrient change won't do any harm either. It's just a
question of minimizing waste. A good tip is to mix the fungi in a
one gallon jug to get it nicely diluted, then pour it into your
nutrient solution. Otherwise the powder can sit at the bottom of
the res. The white powder you sometimes see at the bottom of your
res is just the carrying agent of the spores, not the spores
Q. What mycorrhizae products can I find in my local grow
You'd best ask down at your store! You'll most likely find a few
different brands. The products usually come as a jar of white
powder - this is a 'carrying agent' for the spores. If you want to
compare products, look for the number of mycorrhizal species per
pound and the diversity of species. Oh, and the price!
Q. Ok, but how do I actually use mycorrhizal fungi to benefit
Mycorrhizal application is easy and requires no special
equipment. The goal is to create physical contact between the
mycorrhizal inoculant and the plant root. Mycorrhizal inoculant can
be sprinkled onto roots during transplanting, worked into seed
beds, blended into loose growth media, "watered in" via existing
irrigation systems, added directly to the nutrient solution,
applied as a root dip gel or even probed into the root zone of
existing plants. Most hydroponic growers simply add the fungi by
diluting the powder holding the spores into some water and adding
this to their nutrient solution. It's very easy.
Q. Do mycorrhizal fungi actually guard the roots against other
nasties? If so, which nasties exactly?
Yes. Nasties include: rhizoctonia, fusarium, pythium and
phytophthora. They can also mitigate the detrimental effects of
high salt conditions.
Q. How exactly do mycorrhizal fungi guard the roots? Do they
simply "crowd out" the root zone or is it more complex?
Endo mycorrhizal fungi thicken the cell walls around the root
cortex making it harder for pathogens to penetrate. They also
compete with pathogens for some of the same food sources.
Mycorrhizal fungi help with antibiotic production, armoring of
roots with chitin, and control of excess nutrients.
Q. What's the difference between "endo" and "ecto" mycorrhizal
Endo = has an exchange mechanism inside the root (and hyphae
extends outside of the root). Ecto= lives only outside the root.
The endo mycorrhizae form with mostly green, leafy plants and most
commercially produced plants. Ecto mycorrhizae form with mainly
conifers and oaks: more woody plants. Endos are for everything
else. In hydroponics, ectos don't even matter. Fruits, veg, flowers
... stuff we love to grow ... they love endo.
Q. Are there any differences in how the hydroponic grower
should use mycorrhizal fungi compared with the organic grower?
Both types of grower need to get the inoculum near roots. Same
product, same application rates. Same number of spores per square
foot. Both types of growers can reduce their nitrogen and
Q. Do mycorrhizal fungi help with nutrient extraction in a
hydroponic environment or are they more relevant in soil / organics
where nutrients need to be broken down first in order to become
Mycorrhizal fungi are just as effective in hydroponic
applications as they are in organics / soil. A main function of
mycorrhizal fungi is phosphorus uptake. It's important to have a
good colonization and a good mycorrhizal fungi "web" already
established before you go into flowering.