Are you over 21 years of age?

Grading explained: How is the aroma of cannabis graded?

Grading explained: How is the aroma of cannabis graded?

By Dan Cohn

Aroma is very powerful. It can trigger memories from your childhood, activate your salivary glands when food is cooking and tell you whether or not your cannabis is sublime. Looking at flower can give you an idea of the quality, but when you get that first whiff and it knocks you off your feet, you know you’re in for a treat.

More than just a pleasing scent, the aroma of cannabis is like the DNA tag for a strain, with a specific terpene profile that will produce a smell confirming its identity. It can also tell you about the curing process and even hint at the effects it provides, which is why Big Tree includes it as one of the four main grading qualities.

Terpenes, the volatile, potent compounds that developed over time to repel certain plant predators, give cannabis strains their distinct aroma. This aroma is scrutinized and quantified into a numerical grade on site by Big Tree’s certified cannabis graders. Daniel Wendling is one of those graders, and he marks the importance of a product’s smell by pointing out “aroma is noticeable before you even open your eyes. It’s typically the first criteria I look at.”

Of a common 5lb lot, which is initially inspected for aroma as a whole, graders will physically inspect 3-4 buds if there is a strong scent. If not, they’ll have to go through more of the lot to get a better judgment. Sipping cool water in between inspections serves as a palette cleanser.


Generally speaking, a lot will be presented for grading in a sealed container. For the first step of the process, Wendling says, “from a distance, I’ll open the bag, not put my nose right in it, but just see if you get that first stage of smell, or the top chords.”

What is a ‘chord’ in this context? Terpenes and phenols break free from the flower to create a bouquet of scents which can be categorized as top chords, middle chords and bottom chords.

Top Chords

  • First impression of a smell
  • Initial opening of jar and when bud is broken
  • Evaporate and disperse quickly 5min – 15min
  • Limonene (citrus)
  • Geraniol (floral)
  • Linalool (lavender)

Middle Chords

  • Predominant scent that lingers on olfactory nerves
  • Longer life once airborne 20min – 65min
  • a-Terpineol (pine)
  • β-Caryophyllene (pepper/herb)
  • a- Terpinene (earth)

Bottom Chords

  • Predominant smell from the jar and on your fingers
  • Slowest to evaporate >6 hours
  • Eugenol (clove)
  • Gingerol (ginger)
  • Trans-nerolidol (jasmine)

Top chords are the most volatile compounds and evaporate quickly, in 5-15 minutes, and provide the first impression of a scent. Since they’re the fastest to dissipate, graders try to smell them right away.

“The next step [would be] putting my nose over the bag or over the lot and get a good sense, without touching anything, of that smell.” Still looking for top chords, a pungent smell would denote a better product, whereas a weak smell at this stage would cause the grade to go down. Next, Wendling will “shake the product or the lot to move it around, allowing more open air and causing more of those top chords to break free. Again, keeping my nose above it.”

If top chords are present, the focus then shifts to the middle chords, which have a longer life once airborne, lasting between 30 minutes to 2 hours. At this point, graders will physically touch the product and hold it up a few inches from the nose. If there’s still no scent, Wendling says “then I’m going to actually take the bud and rub my thumb against it as I hold it 2 inches from my nose. That thumb rub should break free some of the undertones or what we call our ‘bottom chords’ of smell. Those bottom chords are going to last about 6 hours if the bag was open and sitting there.”

Finally, as the last resort if a smell is still not present, and with permission from the grower, buds will be broken open. A nice smell from the inside of the bud will keep the score in the middle range, but no smell would be low scoring.


The highest scores of 90 and above come from aromas that are consistently pungent even from a distance. The lowest scores, between 50 and 60, come from very weak smells, only attained by breaking open the product. Scores of 50 and below are negative smells like mold, or non-cannabis smells. Most common cannabis that gets retailed averages between 80-90.

The scents and quality of those scents lead graders to determine a lot about the plant they’re inspecting. Proper curing of the plant, for example, will lead to a strong smell. Lack of smell could mean it wasn’t handled properly after harvest. Additionally, “every strain should have a particular smell that it gets because a certain strain or cultivar has a certain terpene profile,” Wendling explains.

Since different terpenes have their own associated scents, you may be able to anticipate the effect the cannabis will have on you based on which terpenes you smell. Similarly, the aroma can help confirm the identity of a strain: “If you get a Super Lemon Haze,” Wendling suggests, “and you don’t have any limonene smell to it, but it smells like rosemary, it most likely isn’t Super Lemon Haze.” This type of scenario could represent “an accident somewhere along the way on the farm where the product is actually not what it’s supposed to be, cultivar-wise,” according to Wendling.

A high score for cannabis aroma helps growers get a better fair market price for their product by confirming its quality to consumers. Especially in places like Washington State, where the laws don’t allow consumers to smell the product before they buy it, having this score could also encourage people to try different products. Wendling provides a great analogy, “Wine gets graded on a similar 1-100 scale. If I see a bottle of wine that’s a 92 and one that’s an 84, I’m going to buy the 92. I don’t know anything about wine, but I know how to look at numbers.” Like a fine wine, great cannabis will have a nose that tells its story and sets your expectations, all in one whiff.

Read more in the Grading Explained series:

How is cannabis color graded?

How is the structure of cannabis graded?

How is cannabis trichome content graded?

Dan Cohn
Dan Cohn

Dan Cohn is a drummer, audio engineer and music aficionado who enjoys using cannabis to fuel thoughtful conversation, critical listening and relaxing. The first time he made weed brownies, he cut the whole pan into six mega brownies and ate one before a friend's 18th birthday bowling party. He didn't make it to the party.