Terpenes: where the smell of cannabis comes from

Open two jars. One smells of lemon peel; the next of pine, or diesel, or something that manages to be fuel and fruit at the same time. That’s terpenes.

What they are

Terpenes are aromatic compounds and they’re not remotely unique to cannabis — they’re what makes a lemon rind smell like lemon and a pine forest smell like pine. The same handful of compounds turn up all over the plant kingdom.

Cannabis makes them in the trichomes, the same resin glands that hold the cannabinoids. Which is why a flower thick with trichomes usually smells like it means business.

The ones you’ll meet

• Myrcene — earthy, musky, a little like cloves. Also in mangoes and hops.
• Limonene — citrus peel. Also in lemons and oranges, as the name rather gives away.
• Caryophyllene — peppery and spicy. Also in black pepper and cinnamon.
• Pinene — pine and rosemary.
• Linalool — floral, a bit like lavender, which is where most people know it from.
• Terpinolene — hard to pin down. Herbal, slightly fruity, slightly annoying to describe.

Most cultivars carry several at once, and the mix is what makes a cultivar smell like itself rather than like a category.

Why the smell is worth paying attention to

Terpenes are volatile. They evaporate with heat, light and time, so the aroma of a flower tells you something about how it was grown, dried, cured and stored. A jar that smells of almost nothing has either been handled badly or been sitting around a long while, and neither is a secret it can keep.

That’s a practical reason to trust your nose in the shop. It’s a better guide than a name on a label.

What we will and won’t tell you

We’ll happily open a jar and let you smell it, and tell you what the growers told us about a cultivar’s lineage.

What we won’t do is tell you what a terpene will do to you. There’s real research going on into how these compounds interact with cannabinoids and it’s genuinely unsettled — so anybody giving you a confident answer is running well ahead of the evidence. Smell them, pick what appeals, let that be the guide.