Last updated on August 21, 2026 · Originally published October 22, 2021
We live in an antimicrobial world where disease may lurk around any corner and hand sanitizer may seem like a godsend. There’s no doubt that there are microbes that infect our plants and food and can harm or kill us. The flip side is that there are also beneficial microbes like probiotics. Our attempts at ridding ourselves of bad microbes through antibiotics can take its toll on useful bacteria within our guts. In fact, the microbiota of our guts has been found to have massive implications on our well-being. [1]
Do growing conditions change what cannabis produces?
Earth’s flora can benefit from good microorganisms, too, and a 2021 review considered beneficial microbes for Cannabis sativa. [2] When a cannabis plant gets biotically stressed, secondary metabolites like cannabinoids and terpenes can be affected. [3,4] Sometimes it’s the things that bug you that make you stronger.
For example, it’s been shown that things like poor soil [5], potassium deficiencies, and moisture increased delta-9-tetrahydrocannabinol (THC) in hemp [6]. Nitrogen-phosphorus-potassium (NPK) nutrients increased cannabigerol potency in flowers while decreasing cannabinol levels. [7]
Can beneficial microbes be put to work deliberately?
The concentration and abundance of microbiota like bacteria and fungi can be modified by human mediation. The question is can they be modified to augment secondary metabolites in cannabis? The authors point to terpenoid indoles like serpentine in a type of periwinkle that increased when inoculated with strains of Staphylococcus and Micrococcus bacteria. [8]
Molecules like abscisic acid, gibberellins, and ethylene have been evaluated with cannabis [9], and it’s thought that these “exogenous inducers” could synergize with endophytic bacteria native to cannabis, thereby augmenting THC and CBD concentrations. Plant growth-promoting rhizobacteria like Pseudomonas and Bacillus have been considered for their ability to increase cannabinoid yield, but there’s a whole microbiome out there, and different organisms can do different tasks. The authors report “[d]ifferent microbes can colonize various areas of the root, increasing the total root biomass and nutrient acquisition capacity. Some microbial strains protect plants against pathogen attacks, while others improve the resilience and recovery of plants subjected to stress.”
What lives in the cannabis root microbiome?
A genetic analysis can seek out and identify microbial genes that might augment bioactive compounds in cannabis via their specific functionality. The authors elegantly report that “decoding the community profile of cannabis-associated microbes would produce a large list of microbes to choose from and its microbiota would unravel the complexity of stabilizing cannabinoid production.”
A study of five cultivars, including Bookoo Kush, Burmese, Maui Wowie, White Widow, and Sour Diesel identified a central cannabis bacterial population composed of Pseudomonas, Cellvibrio, Oxalobacteraceae, Xanthomonadaceae, Actinomycetales, and Sphingobacteriales. [10] Amazingly, the CBD potency linked with the structure of bacterial communities in the root system, and THC potency associated with soil properties that shape living soil diversity like temperature, pH, and salinity. The cannabis microbiome, in other words, is not one community but many: it varies with the cultivar and with the soil the plant is grown in.
What about mycorrhizal fungi?
Mycorrhizal fungi are the beneficial microbes most growers have actually heard of, and they are marketed harder than any other inoculant. A mycorrhiza is properly the partnership itself — the association between fungus and root — rather than the organism that forms it. Arbuscular mycorrhizal fungi form these symbioses with roughly 80% of vascular plants, trading access to phosphorus and water for sugars from the plant.
Cannabis does host them. Surveys of outdoor hemp have recovered Funneliformis, Glomus, Diversispora and related genera from both roots and surrounding soil, with colonization varying by cultivar and by fertilizer regime. [14] Inoculation trials have found effects on chemistry as well as growth: pairing hemp with Rhizophagus species and endophytic fungi raised fiber fractions and cannabinoid content, cannabidiol in particular. [15]
That distinction is worth holding onto, because it explains why buying “mycorrhizae in a bag” is a slightly odd proposition: what is in the bag is fungal propagules, and whether a mycorrhiza actually forms depends on the plant and the soil it meets.
The effect is conditional rather than automatic, which is the same lesson the biostimulant work teaches. Hemp inoculated with Funneliformis mosseae and grown under moderate salt or drought stress outperformed uninoculated controls on growth, photosynthesis and secondary metabolite accumulation. Under severe salt stress, the same fungus made the plant’s physiology and secondary metabolite synthesis worse. [16] And in an earlier trial from the same group behind the fiber study, hemp inoculated with Rhizophagus aggregatus outperformed every other treatment on biomass and on CBD and THC concentration — but showed no significant advantage over unmycorrhizal plants given synthetic NPK fertilizer. [17] The fungus matched the fertilizer rather than beating it, which makes the case for inoculants one of substitution rather than enhancement.
The partnership is real, in other words, but it is not unconditional.
Do microbial inoculants work in practice?
Microbial biostimulants and beneficial microbe inoculants are already sold to cannabis growers, and the evidence behind them is mixed. A microbial biostimulant called Mammoth P™ boosted aerial biomass by 16.5%, but no cannabinoid enhancement was detected. [11] Other studies have shown that microbial communities can evolve within cannabis with different cultivars revealing different microbial genera. [12] And as mentioned, microbes can stimulate secondary metabolite production. Trichoderma harzianum, for example, stimulated CBD and biomass yield in hemp. [13]
What this means for cultivators
The point of all of this is to harness the power of the “core microbiota” in cannabis to boost secondary metabolites like cannabinoids and terpenes by “selecting microbes that enhance nutrient security, plant health, and chemical compound biosynthesis for a particular genotype…” [2] Given that this approach has worked for many other plants like corn, wheat, and soybeans, and the desire for more stabilized and sustainable cannabis cultivation is of interest, it’s worth diving into the microbial pool to find natural ways to create symbiosis between your plants and their soil.
References
[1] Shreiner AB, Kao JY, Young VB. The gut microbiome in health and in disease. Curr Opin Gastroenterol. 2015;31(1):69–75. doi:10.1097/MOG.0000000000000139
[2] Ahmed B, Hijri M. Potential impacts of soil microbiota manipulation on secondary metabolites production in cannabis. J Cannabis Res. 2021;3:25. doi:10.1186/s42238-021-00082-0
[3] Pate DW. Chemical ecology of Cannabis. J Int Hemp Assoc. 1994;2:32–37.
[4] Gorelick J, Bernstein N. Elicitation: an underutilized tool in the development of medicinal plants as a source of therapeutic secondary metabolites. Adv Agron. 2014;124:201–230. doi:10.1016/B978-0-12-800138-7.00005-X
[5] Krejci Z. Changes with maturation in the amounts of biologically interesting substances of cannabis. In: Joyce CRB, Curry SH, editors. The botany and chemistry of Cannabis. London: J & A Churchill; 1970. p. 49–55.
[6] Haney A, Kutscheid BB. Quantitative variation in the chemical constituents of marihuana from stands of naturalized Cannabis sativa L. in east-central Illinois. Econ Bot. 1973;27:193–203. doi:10.1007/BF02872989
[7] Bernstein N, Gorelick J, Zerahia R, Koch S. Impact of N, P, K, and humic acid supplementation on the chemical profile of medical Cannabis (Cannabis sativa L.). Front Plant Sci. 2019;10:736. doi:10.3389/fpls.2019.00736
[8] Etalo DW, Jeon JS, Raaijmakers JM. Modulation of plant chemistry by beneficial root microbiota. Nat Prod Rep. 2018;35(5):398–409. doi:10.1039/C7NP00057J
[9] Taghinasab M, Jabaji S. Cannabis microbiome and the role of endophytes in modulating the production of secondary metabolites: an overview. Microorganisms. 2020;8(3):355. doi:10.3390/microorganisms8030355
[10] Winston ME, Hampton-Marcell J, Zarraonaindia I, et al. Understanding cultivar-specificity and soil determinants of the cannabis microbiome. PLoS One. 2014;9(6):e99641. doi:10.1371/journal.pone.0099641
[11] Conant RT, Walsh RP, Walsh M, Bell CW, Wallenstein MD. Effects of a microbial biostimulant, Mammoth P™, on Cannabis sativa bud yield. J Hortic. 2017;4:191. doi:10.4172/2376-0354.1000191
[12] Comeau D, Novinscak A, Joly DL, Filion M. Spatio-temporal and cultivar-dependent variations in the cannabis microbiome. Front Microbiol. 2020;11:491. doi:10.3389/fmicb.2020.00491
[13] Kakabouki I, Tataridas A, Mavroeidis A, Kousta A, Karydogianni S, Zisi C, et al. Effect of colonization of Trichoderma harzianum on growth development and CBD content of hemp (Cannabis sativa L.). Microorganisms. 2021;9(3):518. doi:10.3390/microorganisms9030518
[14] Zielonka D, Sas-Paszt L, Derkowska E, Lisek A, Russel S. Occurrence of arbuscular mycorrhizal fungi in hemp (Cannabis sativa) plants and soil fertilized with sewage sludge and phosphogypsum. J Nat Fibers. 2021;18(2):250–260. doi:10.1080/15440478.2019.1618779
[15] Seemakram W, Paluka J, Khota W, Suebrasri T, Lapjit C, Kuyper TW, Boonlue S. Enhancement of fiber content and cannabinoids of hemp using arbuscular mycorrhizal fungi and endophytic fungi. Sci Rep. 2026;16:15829. doi:10.1038/s41598-026-46869-0
[16] Yuan H, Si H, Ye Y, Ji Q, Wang H, Zhang Y. Arbuscular mycorrhizal fungi-mediated modulation of physiological, biochemical, and secondary metabolite responses in hemp (Cannabis sativa L.) under salt and drought stress. J Fungi (Basel). 2024;10(4):283. doi:10.3390/jof10040283
[17] Seemakram W, Paluka J, Suebrasri T, Lapjit C, Kanokmedhakul S, Kuyper TW, Ekprasert J, Boonlue S. Enhancement of growth and cannabinoids content of hemp (Cannabis sativa) using arbuscular mycorrhizal fungi. Front Plant Sci. 2022;13:845794. doi:10.3389/fpls.2022.845794
