Nothing hits the nose quite like the smell of marijuana. It cuts through the heaviest air and dominates every other odor. Even people who have never set eyes on a joint can place the aroma. We all know weed when we smell it.
But why does it smell that way? There are countless other flowering plants in the world, so why don’t they smell the same?
One obvious reason for the uniqueness of pot may be that it is burned far more often than other plants. Few of us ever come within smelling distance of a forest fire, so we have no idea what a burning tree or bush smells like.
Cannabis’ unique smell
Still, tobacco is lit even more often than marijuana, and the two smell nothing alike. To at least some degree, each plant produces its own aroma when it’s burned. And we recognize the smell of smoldering marijuana precisely because we come across it so often. Flaming ferns, not as much.
Of course, weed smells different before and after it is ignited. The burning aroma is smoky and hot but deeply natural, while fresh, unburned bud smells like a combination of Kentucky blue grass, just-picked green vegetables, and upturned top soil. The effect is very much like sticking one’s head in a pile of dirt.
Some claim you can tell the quality of good bud by sniffing it, but that’s nonsense. The same people insist dense nuts are stronger than fluffy nugs, and they’re wrong about that, too. Still, some pot smells better than other. Either way, that first huff from a fat sack is a wakeup call as strong as brewing coffee.
But where does this smell come from?
The answer, at least when it comes to the most pungent aspects of the aroma, is terpenes. These are a class of chemicals found in thousands of flowering plants around the world. Among their many functions, they produce the fragrances of almost every flower.
There are more than 140 terpenes in marijuana, all with important purposes. Some strains contain more than others, and terpenes modify the effects of THC, CBD, and other cannabinoid chemicals produced by the marijuana plant. They also strongly influence the smell.
Terpenes influence the smell of marijuana
Myrcene is the most common terpene found in cannabis. It can also be found in hops, it produces a low-key balsamic odor, and it could be responsible for the unique, relaxing effects of indica weed.
Other terpenes contribute to the thick aroma of marijuana. But THC, the chemical that gets users high and is illegal in most places, has no smell. Drug-sniffing dogs find it by smelling for caryophyllene, a type of terpene that also influences the aroma of black pepper and cloves. As caryophyllene comes into contact with oxygen, it produces a sharp, pungent smell that dogs can easily detect.
Of course, ordinary pot is one thing. “Skunk” is another. This is marijuana that smells especially strong and pungent, with an odor many takers find unpleasant. It’s not clear exactly which chemical or chemical combination leads to this famed eau de cannabis, but it probably involves a precursor to acetyl coenzyme A that has an exceedingly strong skunk-like smell.
Whether it’s subtle or can be smelled from 10 blocks away, weed has one of the best-known odors on the planet. Not surprisingly, that smell is a central part of the user experience. Take away the aroma of pot and it wouldn’t be pot.