The colors of cannabis

Before cannabis was legal “bag appeal” was the most important factor when it came to buying or selling weed. Just like with food, smell and looks are the first things we notice and the first things that form our opinion about it, so buds that had a pleasant and pungent smell and different or interesting looks were always in high demand.

The diversity of cannabis strains today is really wide and consumers can find strains that suit them in effects, grow characteristics, aromas and flavors. Visual differences and uniqueness have always captured the minds of cannabis connoisseurs and have made those strains equally popular among growers and users alike.

Usually, cannabis strains are different shades of green with orange, red or brown hairs or pistils but sometimes flowers take on hues of red, blue, purple or pink. A popular misconception about colored cannabis is that those strains are more potent than the ‘regular’ green but their color has nothing to do with their potency.

Cannabis plants have more than 400 different compounds, after cannabinoids and terpenes, flavonoids are one of the three most important. Unlike the name may suggest, flavonoids have nothing to do with the actual flavor but they do play a crucial role in color pigments.

Chlorophyll – a building block of our food chain

Chlorophyll, which is the main plant pigment, is responsible for sustaining life as we know it and plays a crucial role in the development of the entire food chain from plants to animals. Plants absorb every color of the spectrum except green which they reflect and which accounts for their color. Green color is toxic to plants though and interferes with photosynthesis, stopping the plants in making sugars and food from air, sun and water.

As plants approach the end of their lives, usually in the fall, they start to ensure that their progeny will live on. Days get shorter, light spectrum of the Sun changes and temperatures drop, which is a sign for plants that summer is over and that they should start making seeds. At the end of their lives, plants prepare to bear seeds and green light is allowed to penetrate the plant and genes switch on to code enzymes to produce compounds that turn the color of the leaves to yellow, which is known as the “Fall Effect”.


The plant’s vibrant green color is a sign of good health but as the temperatures drop, they inhibit chlorophyll production. However, plants have many other pigments, including anthocyanins and carotenoids, which are used, in the absence of chlorophyll, by the plant to absorb sunlight and photosynthesis.

Unlike chlorophyll, anthocyanins naturally absorb all light wavelengths, except those in the indigo spectrum which are responsible for the plant’s purple color. Anthocyanins are a flavonoid family you may find in plants such as grapes, eggplants, blueberries, violets or red cabbage and they’re responsible for producing red, purple or blue pigments.

According to a study by Mansouri and Bagheri, flavonoid accumulation is involved in various aspects of the plant’s growth, which includes pigment production, pathogen resistance and protection against UV radiation. Expressing other colors is also a survival mechanism for cannabis plants – it helps them attract pollinators like bees, repeal pests by making them think the plant is sick and to attract more warmth due to their darker color.

Different colors may appear on various parts of the plant – pistils, leaves, calyxes and trichomes. Pistils are usually white in color but they can change their color to purple or pink. Like we said before, the change in color is no indication of potency, they just make the plant more attractive. Calyxes are responsible for bud formation, hundreds of them pile on top of each other and form buds. By controlling light conditions and temperatures, they too can change color from the usual green. The more calyxes that form the bud are present, the more vibrant the bud’s color will be. Different colored leaves are also possible and they help the plant to absorb more heat and also, make it more attractive to pollinators and repel pests. Trichomes change color as the plants mature and they go from being transparent or opaque to white and then to golden amber. Some plants may have trichomes that instead of milky white, exhibit green, purple or pink colors.

Manipulating the environmental conditions

As we said before, lower fall temperatures inhibit chlorophyll production and enable the plants to use flavonoids for photosynthesis. In general, blue and purple hues react to slight drops in temperatures but be careful not to lower the temperatures too much as it may send the plants in shock. If the temperatures are slightly higher than the required levels, some strains may produce gold or red hues instead.

Not all strains will show off these colorful hues, but they have a higher potential of doing so. If you had to expose your plants to colder temperatures, it may result in plants producing less THC. Research on other fruits and flowers has shown that higher temperatures and higher pH levels destroy anthocyanin production, meaning they tend to thrive in more acidic environments.

PH levels are also an important factor when it comes to color pigments.The exact color plants will exhibit depends on the soil pH. Yellow color is developed in alkaline conditions, blue in higher pH, purple in neutral pH, while pink and red colors are best induced by acidic environment.

Different plant pigments are responsible for different colors:

  • Anthocyanin – Blue/Purple
  • Anthoxanthin – White/Cream
  • Carotenoids – Yellow/Orange
  • Chlorophyll – Green
  • Lycopene – Red

UV light from the sun or LED lighting is also known to increase the production of anthocyanins. However, UV light can be damaging for the plants when given in high quantities, so if you’re planning on supplementing your light setup, make sure you know what you’re doing. Plants have multiple defense mechanisms that help them deal with predators, pests, disease or any other ‘threats’. When exposed to the damaging effects of the UV rays, plants produce their own ‘sunscreen’ as a response – various enzymes, antioxidants and other chemicals, including anthocyanins will repair the damage caused by the exposure and change the color as a ‘side-effect’.

Another factor that plays a significant role in the plant’s color is the photoperiod. By reducing the number of hours your plants are exposed to light, you could see the change in color as a result of decreasing the chlorophyll production. This process is more intense during the flowering phase, especially in the last 2 or 3 weeks, and is known as senescence

Human benefits

Some of the plant pigments, such as carotenoids and anthocyanins are also potentially beneficial for human consumption. It is noted that they may have analgesic, anti-inflammatory, antioxidant and neuroprotective properties.

Some studies also indicate that some anthocyanins have an affinity for CB1 or CB2 receptors, interacting with them as cannabinoids such as THC and CBD and contributing to the ‘entourage effect’ – the synergic relationship between cannabis compounds and the endocannabinoid system.