Terpenes are aromatic compounds that plants make. In cannabis they are made and stored in the glandular trichomes, the resin heads, alongside THC and CBD, and they give each strain its smell. Over 120 have been identified in cannabis, mostly monoterpenes and sesquiterpenes. They evaporate easily, which is why fresh frozen and cold cured hash taste the way they do.
What are terpenes?
Terpenes are the aromatic compounds behind the smell of most plants, from pine needles to citrus peel, and cannabis makes a lot of them: a 2021 review from McGill University counts over 120 identified in cannabis. They are why one jar of hash smells of lemon and another of pepper or pine, and they are a large part of what hash makers mean by quality.
Terpene definition
By definition, a terpene is a hydrocarbon built from small isoprene units linked into chains, as a 2020 review from Chiang Mai University puts it. A terpenoid is a terpene that also carries oxygen. Counted in isoprene units, a monoterpene has two, for 10 carbon atoms, and a sesquiterpene three, for 15.
Where terpenes are made
Terpenes are made in the same place as THC: the glandular trichomes, the resin heads on the flowers. The McGill review describes cannabinoids and terpenes forming in a ring of secretory cells at the base of each head and being stored in a cavity just under its outer skin. That is why every hash method, from dry sift to live rosin, is really a way of saving the resin heads, and their terpenes, whole.
Monoterpenes and sesquiterpenes
Monoterpenes and sesquiterpenes are the two main kinds of terpenes in cannabis. Monoterpenes, such as myrcene, limonene and pinene, are smaller molecules with 10 carbon atoms; they are the most volatile and the first to go. Sesquiterpenes, such as caryophyllene and humulene, have 15 carbon atoms, are heavier and linger. Bubbleman tastes the difference in hash: aged traditional hash keeps the peppery sesquiterpene caryophyllene, while fresh hash keeps the bright monoterpenes that used to be cured out.
Common cannabis terpenes
Common cannabis terpenes, and how they smell, from the chemistry records cited in the terpene chart:
- Myrcene: balsamic and peppery.
- Limonene: citrus.
- Caryophyllene: spicy, woody, clove.
- Linalool: floral, like lavender and bergamot.
- Pinene: pine.
- Humulene: woody.
- Terpinolene: sweet pine.
Boiling points for each, and what they mean for dab temperature, are in the terpene chart.
Terpenes and their effects
What terpenes do in the plant is well known, but their effects on people are still being worked out. In the plant they help with defense: the McGill review notes that the monoterpenes pinene and limonene repel insects and sit mostly in the flowers, while sesquiterpenes, bitter to mammals, are higher in the lower leaves. In people, the research is still early. In a 2024 Johns Hopkins study of 20 adults, adding vaporized limonene to a 30 milligram dose of THC lowered ratings of feeling anxious and paranoid, while limonene on its own felt no different from a placebo.
Terpenes in hash and concentrates
Terpenes in hash and concentrates are fragile. They evaporate as a plant dries and cures, which is why fresh frozen plants make the most aromatic hash and why live resin and live rosin exist at all. Heat degrades them too, so a low temperature dab tastes of far more than a hot one. Bubbleman would rather you called them volatile organic compounds: terpenes are the biggest share, but the smell of a jar also comes from thiols, esters and aldehydes, and researchers have reported more than 200 volatile compounds from cannabis.
From the archive: Bubbleman on terpenes
From the archive, Bubbleman on terpenes in his own words, from two live Sunday shows. Tap a time to hear that moment.
Season 12, Episode 21, The art of the perfect pre-roll
You guys call them terps. I would convince you to call them volatile organic compounds because terpenes are the larger percentage, but it doesn’t mean you’re not smelling thiols and thiolates and aldehydes and esters and all these other things that are present in there.
On more than terpenes
New age hashes, well, they have all of these super unique monoterpenes… We’d cure them out by leaving the flower out and allowing them to sort of dissipate. They’re more caustic, they’re a little more harsh on the throat. But when we preserve them, we get that full feeling that we expect from full melt bubble or live hash rosin.
On old hash and new hash
Terpene questions
Terpene questions, answered short:
What are terpenes in weed?
Terpenes in weed are the aromatic compounds that give each strain its smell; they are made in the resin heads alongside THC.
What do terpenes do?
Terpenes do two jobs that are well established: they give cannabis its smell and taste, and they help defend the plant. How they change a high is still being studied.
Do terpenes get you high?
Terpenes don’t get you high on their own: in a 2024 Johns Hopkins study, vaporized limonene alone felt no different from a placebo, though it eased the anxiety of a strong dose of THC.
Where are terpenes found in cannabis?
Terpenes are found in the glandular trichomes of cannabis, the resin heads on the flowers, where they are made and stored alongside the cannabinoids.
What is the difference between monoterpenes and sesquiterpenes?
The difference between monoterpenes and sesquiterpenes is size: monoterpenes have 10 carbon atoms and evaporate first, while sesquiterpenes have 15 and linger longer.
Why do hash makers care about terpenes?
Hash makers care about terpenes because they carry the smell and flavor of the plant and are easy to lose, to drying, curing, heat and time.
Sources for this guide to terpenes
Sources for this guide to terpenes:
- Cannabis glandular trichomes: a cellular metabolite factory (Tanney and others, 2021), Frontiers in Plant Science
- The cannabis terpenes (Sommano and others, 2020), Molecules
- Vaporized D-limonene selectively mitigates the acute anxiogenic effects of THC (Spindle and others, 2024), Drug and Alcohol Dependence
- Dab temperature guide: the best temp for dabs, Puffco
- Terpene talk with Horatio Delbert, Bubbleman’s World on YouTube
- Hash Church Season 12, Episodes 21 and 25: Bubbleman on terpenes, linked above