Would a rose by any other name smell as sweet? Weed is often said to have a scent similar to its namesake — earthy, pungent, and herbal. The odor of cannabis acts as its calling card, alerting nearby noses to its presence. In many jurisdictions, police have grounds to search a vehicle by simply claiming they smell marijuana.
What gives weed its unmistakable smell? Most importantly, what can the odor of cannabis reveal about its quality and potency?
Why weed smells the way it does
Cannabis is often touted as having a signature scent. Although some believe that indica and sativa plants emit distinctive odors, there's no hard evidence to support this. According to experts, aromatic terpenes form the basis for the odor profile of cannabis. Terpenes are highly aromatic botanical compounds found in flowers and plants. As many as 140 terpenes have been identified in marijuana, of which 17 are common.
Distinct combinations of terpenes create diverse fragrance profiles that can influence marijuana consumers' preferences. Some cannabis cultivars contain as many as 66 different terpenes.
The single most significant factor influencing the smell of marijuana is its age when harvested. Cannabis that has been harvested at a younger age has a milder, less skunky scent, while weed that's mature tends to have a more earthy aroma.
The most common cannabis scents
Adjectives used to describe cannabis often include musky, spicy, woody, peppery, citrusy, and tropical. These scents tend to correlate with the terpene profiles of weed strains.
Some of the most common terpenes found in cannabis can make weed smell like the following aromas:
- Myrcene: earthy, musky, herbal aromas comparable to mangos or thyme
- Β-caryophyllene: a woodsy, peppery, clove-like scent
- Α-humulene: earthy tones with spicy notes, similar to beer
- Α-pinene: pine needles, rosemary, and basil
- Limonene: lemon notes, like citrus peel
- Linalool: a floral fragrance also found in lavender and rosewood
Other aromas prominent in good weed are thiols, sulfur derivatives naturally produced by the cannabis plant. These pungent compounds are found in garlic, natural gas (to which it's added), onions, rotten eggs, and skunk spray, giving skunk weed its namesake. Rest assured that cannabis that smells like skunk is actually a good thing as thiols are super-efficient antioxidants.
What does scent reveal about a strain?
Different strains boast their own terpene profiles. The odor can offer subtle insights into the effects of the strain. While cannabinoids wield a strong impact over the mind and body, terpenes are also responsible for some of the effects of cannabis. For example, zesty, zingy-smelling marijuana is likely to contain higher concentrations of limonene, which has been clinically shown to boost mood and serotonin levels and reduce anxiety.
A 2018 study published in Plos One asked participants to characterize 11 different strains of cannabis by sniff samples. None of the participants had been trained in sensory description, but almost all were cannabis users. The researchers found that the participants could consistently discriminate between the 11 strains and that the strains formed clusters based on their odor similarity. Cluster A included weed that smelled earthy, woody, and herbal, while Cluster B referred to cannabis with citrus, lemon, and sweet notes.
Participants were more likely to align the citrus/lemon/sweet cluster with greater potency and quality. This perception has no relationship to THC content, however, because THC is odorless. As the researchers of the study pointed out, few studies to date have related the smell of marijuana directly to its chemical composition.
Raw, cured, and smoked weed: Why do they all smell different?
Unsurprisingly, weed smells discernibly different in its various forms. Changes in chemical composition occur when cannabis is harvested, cured, and smoked.
Cannabis tends to smell pungent, earthy, and complex during the growing process, and most potent when the bud is in bloom. Many home growers observe that some of the subtle notes of the bouquet fade in the days following harvest, with the cut plant taking on a more weed-like smell. This change in aroma occurs because the volatile terpenes can begin to degrade and oxidize.
Curing cannabis can help to preserve the terpenes and the unique scent and flavor profile of the strain. A slow and thorough cure can protect terpenes and preserve the integrity of the plant's potency.
When it comes to smoking weed, the natural smell of marijuana is intensified in the smoke it emits. Combustion adds different layers to the plant's scent: ash, fire, and even the aroma of rolling paper can alter the smell. As many have likely experienced, marijuana smoke can often cling to skin, hair, clothing, and surfaces, leaving traces of its presence long after the last puff.
Scents that signal something's off
The nose knows. While the smell of weed can indicate freshness or maturity, it can also point to the presence of mold or bacteria. Stashes of weed that have been improperly cured or stored may harbor traces of moisture, which provides the perfect breeding ground for mold.
If your weed smells like an unaired closet, urine (gasp), or like a sweaty locker room, the cannabis may be infected with mold spores. Basically, the scent of moldy cannabis is repugnant. If a whiff of the weed in question has you recoiling, you may have a spoiled batch on your hands. Moldy weed is not safe to smoke, as the fungus spores can be inhaled directly into the lungs, leading to potential infection. If you don't trust your nose, there are other techniques you can use to check your cannabis.