What mycorrhizae do
Partnership
Fungi live on and in roots, trading minerals for plant sugars
Gains
Better nutrient uptake, extra fungal compounds, some pathogen cover, and less drought stress
Result
Stronger roots, more disease resistance, and often better yield and flower quality
Groups
Ectomycorrhizae mostly partner forest trees and likely do little for cannabis
AM fungi
Arbuscular types are the ones that matter here
How AM fungi work
Hyphae
Fine filaments enter between the cell wall and membrane and act like extra root hairs
Chemistry
They dissolve phosphorus and many micros, then deliver them inside the root
Glomalin
The glycoprotein they shed is carbon-rich, feeds microbes, and glues soil into aggregates
Reach
Mycelia are thinner than roots, so they mine poor soil more thoroughly
Shield
A living cover plus warning chemistry can make roots harder for pathogens to attack
When to inoculate
Sterile mix
Fresh, lifeless media yield less than inoculated or previously used living mix
Early
Add AM fungi while plants are small so the colony grows with the roots
Reuse
Second and third runs in colonized mix often outyield the first
Carryover
Blend a little old mix into new media if you want the same biology
Phosphate
Most soil phosphate is locked. Fungi plus root hairs move orthophosphate to the canopy
Other allies
Trichoderma
Common soil fungi that can parasitize other fungi and boost root growth. Strains differ in what they control
Bacteria
Some Bacillus types suppress pathogens. Others, including certain Pseudomonas and related groups, raise available phosphorus
Skip the pitch
A wide inoculant can help, but forest ectomycorrhizae on the label are mostly unused by cannabis
Living soil
Biology needs air, moisture, and carbon. Over-sterilizing or staying waterlogged wipes the advantage