Most of the cannabis plants we know produce green buds. However, the strains from The Red Family come out of the pattern and adopt reddish, purple or bluish tones. The adjectives red, purple and blue stimulate the curiosity of the growers but, in cannabis, the color is not only a matter of aesthetic beauty. They are the expression of a whole range of very special molecules. We are talking about the anthocyanins, which are also responsible for the coloration of many dark fruits and for most of the autumnal tones.
The purple color shown during flowering by the plants from The Red Family genetic collection is the result of its richness in anthocyanins (from the Greek anthos, flower + kyáneos, blue) These are water-soluble pigments that are present in plant cells and contribute to the production of red, purple or blue colors in leaves, flowers and stems of the cannabis plant.
Several hundred different anthocyanins are known and they produce a wide range of colors: malvidin gives purple; the flavones, yellow; the delphinidin, blue; the cyanidin, violet; pelargonidin, red and orange. The combination of several of these anthocyanins in the same tissue in different patterns of concentrations generates a wide variety of intensities, tones and colors.
Anthocyanins have been found in all tissues of plants, including leaves, stems, roots, flowers and fruits. In cannabis they are not present in the roots and very few can be found in the seeds, but in the leaves, stems and flowers the anthocyanin contents can reach up to 2.5% of the total dry weight.
It is possible to extract purple and pink resins from the buds of red-flowered plants. The anthocyanins that give the red color to the bud are also present inside the resin glands (trichomes), producing extractions of beauty like no other.
Dark fruits and vegetables such as plums, blackberries, grapes, cranberries, cherries, aubergines, or red cabbages, are rich in anthocyanins.
Anthocyanins belong to the group of flavonoids (from Latin flavus, yellow), which are a series of secondary metabolites of plants. There are four classes of flavonoids: flavonoids, isoflavonoids, neoflavonoids and anthocyanins.
Flavonoids have different functions in plants, which vary according to the species:
Not all colors seen in cannabis that are not green are due to anthocyanins. In varieties that do not produce purple, blue or red colors, often appear golden, orange or yellowish tones at the end of flowering due to carotenoids. Carotenoids are pigments naturally present in the tissues, but they are not usually seen, because they are camouflaged by the intense green of chlorophyll. When a leaf loses chlorophyll it becomes yellow because the carotenoids, which were already there, become visible.
With anthocyanins seems like it does not happen in the same way, because the plants produce them especially at the end of their life cycle, when flowering is about to finish and the days get shorter. In this stage of the life cycle of the cannabis plant the production of chlorophyll decreases and all energy is concentrated in the production of flowers and seeds, but the production of anthocyanins increases at this stage. As the chlorophyll disappears from the tissues of the plant, anthocyanins and other pigments become more visible. It is possible that the anthocyanins help the plants to cope better with the maturity stage, to resist the damage produced by ultraviolet radiation, keeping the herbivores at a safe distance while the seeds complete the maturation process.
It is evident that not all marijuana plants turn purple during flowering. What causes this color change and why does it happen? The answer must be sought, first of all, in genetics. The varieties from The Red Family collection have been subjected to hybridization and selective breeding programs to introduce and fix the genes that promote red coloration, getting to a point where 95% of the individuals acquire purple and reddish tones.
At Sweet Seeds® we work hard on the selection of parent individuals to bring these genetics to 100% of coloured individuals.
Just as the potency of the effect, the aroma or the thickness of the buds is determined by the genes of the specific strain, the same thing happens with the purple coloration. In its origins, most of the purple varieties used to be Indica or hybrids with Indica predominance. They usually contained Kush or Afghan genetics. The effect of these strains used to be mainly relaxing and narcotic, as usual in Indica genetics.
To introduce the red-flowered trait in the first varieties of The Red Family, in Sweet Seeds® we used a genetic from Pakistani Hindu Kush ancestors from the Chitral area, close to the border with Afghanistan. We are currently working with other red-flowered varieties to expand the gene pool of our The Red Family.
Many varieties only develop purple tones in certain climatic conditions, especially when nocturnal temperatures are cold. A summer with a cold end gives reddish, purple or bluish colors to outdoor plants while the plants tend to keep the green color with high temperatures at night. In cold weather conditions cannabis plants produce less chlorophyll (the pigment responsible for the green color in plants). This allows other pigments to be even more visible. Until a few decades ago there were no varieties capable to acquire this color with warm temperatures but the great work done by breeders and seed banks has finally covered this gap.
The Red Family genetic collection adopt these colors in every conditions and in almost all specimens. In some strains the purple color only shows up in the largest leaves, but in The Red Family, even the inner parts of the buds and the trichomes are reddish. It is a joy to be able to observe through macro photographs the red filaments that develop inside the trichomes.
Nutrient deficiencies can also influence the colors of the plants. The petioles of the leaves (the little stick that binds them to the stem) can turn purple due to a lack of phosphorus or nitrogen. The lack of sulfur sometimes causes purple lines on the stems.
The first requirement to get purple buds is to grow a variety that features this characteristic. Although the mechanism responsible for this colouring is not precisely known, it is understood that there is an important relationship between cold temperatures and the production of anthocyanins in marijuana. Many varieties require cold nights for the purple color to appear and remain completely green if temperatures are warm.
The temperature difference between day and night is also an important influential factor. If the temperature at night is more than ten degrees Celsius below daytime, anthocyanins are more easily shown. This also happens with strains that turn purple regardless of the temperature, as it is the case of the strains from The Red Family. Even though, a more intense coloration is obtained when the night temperatures are low and the daytime temperatures are high.
Outdoors, cold nights are helpful to increase the coloration of cannabis plants, but they are not necessarily helpful to improve their potency. In general, cold temperatures negatively affect the THC production. It is very important to stop using nitrogen in the second half of flowering and completely stop fertilizing in the last two weeks of life of the plants to help enhancing the use of the nutrient reserves present in the leaves and also to help enhancing the red, purple and blue tones.
It is known that there is a relationship between pH and the color expressed by anthocyanins, being it more reddish when the acidity is greater and more bluish with higher alkalinity levels. With intermediate pH conditions purple tones appear. In addition to the tone, the pH could influence the amount of anthocyanins produced. According to studies carried out in fruits, production is higher under conditions of acidic pH.
Andre C. M., Larondelle Y., Evers D. (2010). Dietary antioxidants and oxidative stress from a human and plant perspective: a review. Curr. Nutr. Food Sci. 6 2–12. 10.2174/157340110790909563
Flavonoids in general, and anthocyanins in particular, feature important pharmacological and therapeutic properties that have incited the interest of scientists. They have shown several properties in in vitro tests. Among other properties, they are antioxidants, antiallergic, antibiotics, anti-inflammatory, neuroprotective and anti-carcinogenic.
Flavonoids could protect against the action of free radicals, oxidizing molecules, ultraviolet radiation, atmospheric pollution and many other pollutants. In theory, taking into account the properties observed in laboratory, the consumption of flavonoids could reduce the risk of cancer, reduce allergic manifestations, relieve arthritis, reduce cholesterol, stimulate the heart, improve circulation, prevent cardiovascular diseases, protect the liver, fight aging, diabetes and obesity and a long list of other benefits, although more research needs to be performed to be able to say it for sure.
Humans ingest flavonoids when eating vegetables and these are likely to be partially responsible for the resulting health benefits of diets rich in fruits and vegetables. Some of the richest foods in anthocyanins, such as blueberries, goji berries or blackberries are considered very beneficial for health, especially for their antioxidant properties.
In studies with rats it has been observed that anthocyanins are able to cross the blood-brain barrier and reach the areas of the brain responsible for learning and memory. It is possible that the presence of anthocyanins may have an impact in the cannabis effects on short-term memory, potentiating or mitigating them.
23 flavonoids and anthocyanins have been found in cannabis and it is known that some of them keep their pharmacological properties in both vapor and smoke forms. Scientists use the entourage effect in order to explain that the pharmacological effects of cannabis are the result of the interaction of the large number of molecules present in the plant. Cannabinoids, especially THC, are primarily responsible for the effect, but terpenes and flavonoids also have an influence. Terpenes and flavonoids are probably responsible for the huge differences in the effects of different varieties that feature similar proportions of cannabinoids. Some anthocyanins feature a determined selective affinity for receptors of the human body’s endocannabinoid system, with some types of junctions with CB1 and CB2 receptors.
The main flavonoids present in cannabis are:
Most of these flavonoids and anthocyanins can present a synergic behaviour working collectively with the cannabinoids and terpenes also present in the cannabis plant, enhancing their effect by acting together. For example, there are cannabinoids, terpenes and flavonoids with anti-inflammatory effects and, without any doubt, the overall effect of several of them, all together, increases the therapeutic effect through synergies and different ways of acting.
Some flavonoids inhibit certain liver enzymes and could influence the pharmacokinetics of THC in the liver and therefore in the perception of the effect of cannabis itself.
