Terpenes give each cultivar its smell and flavor, and cannabinoids like THCA and CBDA drive potency. Genetics set the blueprint, while growing conditions and post-harvest handling decide how much of it you keep.
Researchers at the University of British Columbia identified about 30 terpene synthase genes, the genes that build cannabis aromas such as limonene, myrcene and beta-caryophyllene. On the commercial side, an analysis of nearly 90,000 lab-tested samples from six US states found that indica, sativa and hybrid labels don’t reliably predict a product’s chemistry.
Growing and handling choices matter too. Supplying a high share of nitrogen as ammonium reduced both cannabinoids and terpenes. Light intensity had little effect on potency. After harvest, monoterpenes were the most fragile compounds, dropping sharply in storage whether flower was packed under nitrogen or air.
Gaps we’re still filling: controlled studies of how specific growing practices raise terpene production in drug-type cannabis.
Key terms
Terpenes
Aromatic compounds that give cannabis its smell and flavor. Monoterpenes (like myrcene and limonene) are lighter and more volatile than sesquiterpenes (like beta-caryophyllene).
Chemovar
A chemical variety: plants grouped by their cannabinoid and terpene profile rather than by strain name.
THCA and THC
Living cannabis makes THCA, an acid form. Heat and time convert it to THC. CBDA and CBD work the same way.
Decarboxylation
The chemical change that turns acid cannabinoids (like THCA) into their neutral forms (like THC), driven by heat and time.
Studies
7 studies
The phytochemical diversity of commercial Cannabis in the United States
PLOS ONE · 2022
Drug-type cannabis
Data analysis
Open access
Indica, sativa and hybrid labels don’t reliably predict a product’s chemistry.
Authors: Christiana J. Smith, Daniela Vergara, Brian Keegan, Nick Jikomes
17(5):e0267498
Study plant: Lab-test results from nearly 90,000 commercial cannabis samples across six US states
Analyzing cannabinoid and terpene lab results from nearly 90,000 commercial samples across six US states, researchers found a small number of distinct, recurring chemical profiles. Those profiles did not line up consistently with indica, sativa or hybrid labels, and some strain names were far more chemically consistent than others.
Terpene profiles are largely set by genetics: about 30 terpene synthase genes were identified.
Authors: Judith K. Booth, Jonathan E. Page, Jörg Bohlmann
12(3):e0173911
Study plant: Genetic and chemical analysis of cannabis plants, including the hemp cultivar ‘Finola’
By analyzing cannabis genetic data alongside resin chemistry, the researchers identified about 30 terpene synthase genes, the genes that build cannabis aroma compounds, and characterized the enzymes behind several major terpenes. These include limonene (lemony), myrcene (earthy) and beta-caryophyllene, a terpene that also interacts with cannabinoid receptors.
Improved Long-Term Preservation of Cannabis Inflorescence by Utilizing Integrated Pre-Harvest Hexanoic Acid Treatment and Optimal Post-Harvest Storage Conditions
Plants · 2024
Drug-type cannabis
Controlled experiment
Open access
THCA fell 4–23% over four months; a pre-harvest spray plus vacuum storage kept losses lowest.
Authors: Matan Birenboim, Daniel Chalupowicz, David Kenigsbuch, Jakob A. Shimshoni
13(7):992
Study plant: One high-THCA chemovar, stored for four months after harvest
A high-THCA chemovar was sprayed with hexanoic acid before harvest (or left untreated), then dried, cured and stored for four months with or without vacuum sealing. THCA fell by 4–23% during storage, with the smallest loss in plants that received both the pre-harvest spray and vacuum storage. The spray protected monoterpenes more than vacuum storage alone, and treated plants had higher levels of some cannabinoids at harvest.
In Pursuit of Optimal Quality: Cultivar-Specific Drying Approaches for Medicinal Cannabis
Plants · 2024
Drug-type cannabis
Controlled experiment
Open access
Controlled-atmosphere chambers dried at least 60% faster, kept terpenes, and reduced mold seen with traditional drying.
Authors: Matan Birenboim, Nimrod Brikenstein, Danielle Duanis-Assaf, Dalia Maurer et al.
13(7):1049
Study plant: Two medicinal chemovars (a high-THC ‘240’ and a hybrid ‘Gen12’)
Two chemovars were dried in controlled-atmosphere chambers with different gas mixes, including nitrogen-rich and low-oxygen blends, and compared with traditional drying. The chambers cut drying and curing time by at least 60% while preserving terpenes. Traditionally dried buds were heavily infested with Alternaria mold and showed some Botrytis. The best gas mix differed by chemovar and by terpene type.
Is nitrogen-modified atmosphere packaging a tool for retention of volatile terpenes and cannabinoids in stored Cannabis sativa inflorescence?
Journal of Cannabis Research · 2024
Drug-type cannabis
Controlled experiment
Open access
Nitrogen-flushed cans didn’t preserve total terpenes or cannabinoids better than ordinary air.
Authors: Luke L. MacLaughlin, Mason T. MacDonald
6:42
Study plant: Dried flower from five cultivars grown at a licensed facility, canned and stored for 74 days
Dried flower from five cultivars was canned either under nitrogen (about 4% oxygen) or ordinary air, then analyzed for 17 cannabinoids and 61 aroma compounds over 74 days. Nitrogen packaging made no significant difference to total cannabinoids or total volatile terpenes, though it shifted some individual compounds. Monoterpenes declined sharply in both treatments during storage.
Nitrogen Source Matters: High NH4/NO3 Ratio Reduces Cannabinoids, Terpenoids, and Yield in Medical Cannabis
Frontiers in Plant Science · 2022
Drug-type cannabis
Controlled experiment
Open access
High-ammonium feeding cut flower yield by up to 46%; moderate ammonium (10–30%) was fine.
Authors: Avia Saloner, Nirit Bernstein
13:830224
Study plant: Medical drug-type cannabis fed 200 mg/L nitrogen in five ammonium/nitrate ratios
Medical cannabis was fed the same total nitrogen (200 mg/L) supplied in five ratios of ammonium to nitrate, from 0% to 100% ammonium. Raising the ammonium share generally hurt the plants: flower yield, cannabinoids, terpenes and photosynthesis were highest on nitrate alone, and yield fell 46% as ammonium rose from 0% to 50%. Moderate ammonium levels (10–30%) caused little harm.
Cannabis Yield, Potency, and Leaf Photosynthesis Respond Differently to Increasing Light Levels in an Indoor Environment
Frontiers in Plant Science · 2021
Drug-type cannabis
Controlled experiment
Open access
Yield rose steadily with light up to 1,800 µmol·m⁻²·s⁻¹, and potency didn’t change.
Authors: Victoria Rodriguez-Morrison, David Llewellyn, Youbin Zheng
12:646020
Study plant: Drug-type cannabis flowered indoors under sole-source LED lighting
Plants were flowered under a wide range of canopy light levels to see how intensity affects yield, potency and leaf photosynthesis. Dry flower yield kept rising in a straight line all the way up to 1,800 µmol·m⁻²·s⁻¹, even though individual leaves stopped gaining photosynthesis well below that level. Light level had no effect on cannabinoid potency and only minor effects on terpenes. The authors conclude that leaf-level measurements are a poor guide to whole-plant yield.