What does cannabis smell like, and what causes its aroma?

The Cannabis genus, or the Cannabaceae plant family, contains a number of different plant species, each of which produces different variants, or cultivars, of cannabis plants that are colloquially known as strains. 

In the broad sense of scents, cannabis has an easily recognisable aroma, and to the untrained nose, most cannabis plants and cannabis aroma profiles probably smell the same. This is because many cultivars within the cannabis genus contain the same chemical compounds, which form these scent archetypes. 

However, in fact, each of these cultivars, or cannabis plant species, smells slightly different - because these compounds vary in concentration from strain to strain. 

Why do different cannabis strains smell different?

Each cannabis cultivar, or strain, has its own diverse molecular makeup of aromatic compounds that all factor into how it smells, so it is difficult to give a concrete cannabis smell description. 

Terpenes, flavonoids, and volatile sulphur compounds are the main aromatic compounds within cannabis that are thought to influence its scent, and their presence affects how the plants overall aroma. 

As well as these compounds, the plant’s freshness, when it was harvested, and the end product the plant is manufactured into, also all impact the smell and aroma of a particular cannabis plant. The unique combination of each of these factors gives each cannabis cultivar, or strain, its own unique scent. 

This can be replicated in standardised, controlled environments, such as when curating medicinal cannabis, but a completely standardised scent from batch to batch is, understandably, rarely achieved by novice cultivators, due to this large number of variables. 

So, what are volatile sulphur compounds?

The underlying ‘skunky’ or sulphuric like-smell to cannabis is believed to be attributed to a family of volatile sulphur compounds, or VSCs in cannabis. Much like terpenes, volatile sulphur compounds are the origin source of many natural scents, and they are particularly odorous. 

One particular VSC, namely 3-methyl-2-butene-1-thiol or Prenythiol, is found abundantly in pungent, strong smelling cannabis cultivars, and is believed to be the main culprit, or primary odorant, for cannabis’ skunky smell. 

Recent findings from greenhouse experiments also determine that the levels of Prenythiol in cannabis increase significantly during the last stages of the flowering process, and reach their maximum potency during the curing stage. 

These same experiments determined that after ten days of storage, the level of present VSCs drops dramatically, which explains why fresh cannabis has such an intense smell in comparison to that that has been stored for a number of weeks.

How do terpenes affect cannabis’ aroma?

Other identifiable traits within cannabis’ aroma can be attributed to the terpenes the species contains. Terpenes are a type of natural compound that can be found in all different kinds of plants from flowers, to fruits, to herbs, and spices. 

Over 400 different types of terpenes have been discovered in cannabis plants around the world, and each terpene has its own characteristic profile, which can contribute to the scent, or therapeutic value of cannabis.

With its base note believed to be created by VSCs, terpenes add extra dimensions to the smell of cannabis cultivars, and can influence the plant to smell more sweet, spicy, or sour, and so on, depending on their concentration within the plant. 

This is why some cannabis cultivars, or strains, smell more earthy or musky, whilst others smell citrusy or floral. 

Some of the most commonly found terpenes in cannabis are:

• Limonene - smells like citrus, and can also be found in lemon and orange trees. 
• Linalool - has a floral and herbal scent, and is also found in chamomile and lavender. 
• Pinene - as its name suggests, this terpene can also be found in pine trees and gives them their distinctive, woody, piney aroma. 
• Myrcene - typically smells earthy or musky, but can add sweet elements to the aroma. Myrcene is also found in lemongrass, hops, thyme, and even in mango. 
• Beta-caryophyllene - has a peppery, spicy and slightly woodsy smell, and is naturally also found in cloves and hops.   
• Humulene - has an earthy and slightly bitter or spicy scent, and is also found in ginseng.

Can flavonoids impact the taste and smell of cannabis?

Although like terpenes, flavonoids have also been found to be abundantly present in different plant species across nature, the scientific research into this class of chemical compound is limited in comparison to terpenes. 

It is believed that flavonoids, or cannaflavins - which are a type of flavonoid only found within cannabis - can influence cannabis’ characteristics in a number of ways, including the way it smells, tastes and looks. 

Working synergistically with the terpenes present, which admittedly do most of the scent related leg work, cannaflavins can affect aroma, whilst dictating its flavour as a flower, and often its colour as well. 

Currently, it is generally accepted that flavonoids have a minor influence on cannabis’ aroma in comparison to terpenes and VSCs’, but they are still believed to contribute, and so, still warrant a mention.

What other factors influence the way cannabis smells?

Just like with its other characteristic features, over time, cannabis cultivators can design and curate their plants to have a particular smell. This is done through selected breeding processes, capturing certain characteristics they’d like to replicate or adapt to create a new hybrid species. 

Sometimes this involves breeding plants that contain especially high levels of VSCs to produce a plant that is particularly pungent, or breeding plants with terpenes that have more of a conventionally pleasant smell, such as limonene and linalool, to improve the sensory experience for the consumer.

Cannabis harvesting and aroma

Another factor that influences the way cannabis smells is when it is harvested. Typically, the later cannabis is harvested, the more potent it smells. This is because its terpenes and VSCs, much like its cannabinoid contents, are continually produced as the plant matures, and reach their peak level once the cannabis plant reaches full maturity. 

The form in which cannabis has been manufactured into, or is sold in as its end product, also affects the way it smells. Just like when cooking, when cannabis is heated, its aroma intensifies and alters slightly, and so, when dried cannabis flower is vaped - it has a different scent to a cannabis-based tincture for example.

Cannabis storage and smell

Other factors during the growing, harvesting, drying, or storage stages can all also influence or change the way a particular cannabis cultivar smells. Contaminants or impurities such as mould can cause cannabis to develop mycotoxins, which have a musty, stagnant odour that can penetrate the plant and take over its natural aromas and flavours.

As well as ruining the taste and smell of cannabis, mycotoxins can be extremely dangerous to health - so their pungent smell acts as a front line defence - warning consumers something isn’t quite right with their cannabis.

Can cannabis be smell-proof?

In certain situations, or perhaps due to personal preference, some medical cannabis patients utilise different methods of controlling or concealing the strong smell of their medication. 

Whilst common tactics that can easily be enacted at home are most popular, such as masking the smell with scented candles, essential oils, or incense, keeping cannabis in an airtight jar, or investing in an air filter or purifier, there are some other, lesser-known tips and tricks that can help to keep that smell down. 

This includes regularly cleaning dry herb vaporizers and their cannabis cartridges or capsules to ensure any built up residue isn’t reheated, and therefore re-released when used the next time, which will help keep the odour to a minimum. 

In addition to regularly cleaning paraphernalia, it is also important to regularly clean and wash the fabrics that come into contact with cannabis - such as soft furnishings, clothing, or accessories to reduce that lingering smell. 

Some medical cannabis patients note that fabrics made from natural fibres are the best option for these items because they do not retain odours in the same way synthetic fibres do. Unlike natural fabrics which are more breathable and porous, fabrics like nylon and spandex absorb the smell of cannabis very quickly, which is worth bearing in mind if it is a smell you are not fond of. 

Whatever your own personal preference, we hope this blog has inspired you to follow your own nose, and become curious about cannabis.