Whenever the subject of colors in cannabis comes up, I’m reminded of the time I was working with a grow partner near Errington in the central Vancouver Island region. We had been growing a variety of strains because we were determining what grew well in the area and had a bunch of clones that had to be tried out.It was a good grow year with plenty of sunny days, though not as much rainfall as we would have liked. As the season neared its end, the nights got colder but the days were still bright and clear and the plants were ripening well; we were doing a selective harvest – taking down the various plants as they finished. The harvest was almost complete and there were only a few more plants to be cut down.
We were working our way through some blackberry bushes towards a Timewarp hybrid when I heard my partners exclaim “Shit! It’s gone”. Having discovered earlier that day we’d had some of our plants ripped off, I rushed towards him, my mind racing with thoughts of poachers. Emerging from the bushes seconds later, I saw what my partner had missed and started laughing as my tension dissolved. Quickly gaining control of my mirth, I pointed out that my partner was standing within a few feet of a beautiful nine- or ten- foot plant. He hadn’t seen it simply because it was purple; the stalk, stems, and every leaf on the plant were purple; “It doesn’t look like cannabis to me,” he said with a sheepish grin.
The colors of cannabis are a highly debated subject with different schools of thought prevailing as to why cannabis displays different hues. Many growers feel that reds, pinks and purples indicate a stronger, more potent bud; others feel that the sight of any other color but green indicates that that plant was grown in a cold climate. Cooler temperature is just one factor in the color of your bud, and while purple bud may be amazingly potent, you’ll find green bud that’s just as amazingly so. Long time growers attest to the exceptional variety of colors attainable in your everyday marijuana crop.
An annual plant, cannabis completes its life cycle within one year, starting as a seed, then germinating, maturing, reproducing, and dying. For a large part of its life, cannabis is green, the color a result of chlorophyll, a chemical significant to the plant’s photosynthesis ability. During the vegetative phase of its life, cannabis will be a shade of green that can be used as a health indicator of the plant.
A healthy plant exudes a vibrant green luster, whereas leaves and stems suffering from nutrient deficiencies change from green to various other colors. Nitrogen deficient plants produce yellow leaves, a sign of diminished chlorophyll production. Plants lacking phosphorous produce small, dark green leaves with purple veins, purple leaf stems, and purple-streaked stocks. When a plant lacks potassium, the leaves turn yellow, then brown and eventually die. Deficiencies in zinc, magnesium and calcium all cause color changes.
While color changes in plants can indicate the state of deficiencies, colour change can also occur in healthy vigorous marijuana plants. Color differences in the leaves of healthy plants are a result of genetic and environmental influences, and also occur as plants near the end of their life cycle. Pistil color changes are influenced by the grow medium’s pH effect on the fragile female cannabis flower.
The beautiful green of the cannabis plant wasn’t the only color present during the vegetative stage, but until the lengthening dark cycle triggers the plant to stop production of the green chlorophyll, we can’t begin to see the yellow and gold color of the carotenoids. It is perfectly natural for cannabis leaves to change colors and die off as the plants reach their “autumn” or finishing stage, showing varying shades of green, yellow, gold and more.
Some plants will turn red and purple as anthocyanins are produced using excess sugars in the leaves and spreading through cell fluids. The pH of the cell fluid determines the color variation, with an acidic fluid producing reddish hues, and an alkaline fluid producing blues. Cellular pH being genetically regulated, each strain has its own unique combination of chlorophyll and carotenoids and potential for anthocyanins production, giving a great splash of color to a diversified grow as nights grow longer and temperature cools. Many strain’s color range is limited exclusively to greens and yellows through the life cycle.
In addition to the autumnal color changes in the leaves, many species show color in their stems when finished in cooler temperatures. Some, like Blackberry from VISC (Vancouver Island Seed Company) and Blueberry, have colored buds in all but the warmest grows; the colors in these buds can change intensity and even hues when subjected to colder nights. While these colors are caused by the same plant components as in the leaves, there is the genetic roll of the die here. Black (see pictures of Black at
www.vancouverseed.com) is a phenotype whose bud is always a dark purple in any temperature grow, yet Black hybrids will grow in colors ranging from purple to mauve to white. The purple color seems dependent on receiving a recessive gene from both parents, which allows for greater glucose conversion into anthocyanins, and having a suitable cellular pH. Not related to size or to resin production, bud color is purely aesthetic in value.
While small and slight, the pistil (reproductive flower) of the female cannabis plant, can have an impact far greater than its size on your overall impression of the plant.
Fucking Incredible by VISC is a plant whose pistils can change colors. Certain nutrient formulations with a pH level of 6.8 cause F.I. to produce buds with reddish pink or even magenta pistils, while the same plant grown in a lower pH will develop white pistils.
Marijuana plants aren’t the only examples of flowers that can react to the pH of their medium. The hydrangea (Hydrangea macrophylla) has flowers that change colors – pink in alkaline and blue in acidic. This is a great example of interplaying environmental and genetic influences. While all strains are affected by adjusting the pH of the soil, the few that exhibit coloured pistils as a result are a visual joy in your grow.
It is generally believed that the pH of a plant’s cells is genetically regulated and not influenced by the growing medium’s pH, and the change of colors can be explained by the plants ability to absorb certain elements only in suitable pH soil. In the case of the hydrangea flower, the blue color is the result of the plant’s intake of aluminum, something most garden soils contain, which will not be useable by the hydrangea in alkaline soil.
I have witnessed the amazing array of colors naturally available in this fantastic plant for decades, and am continually amazed by the diversity. I have also seen growers “creating” gold coloured weed by starving their plants, and others trying to change the colors of the bud by watering with Kool-Aid.
As a longtime breeder of cannabis, I am not a scientist and haven’t tried to bring an exhaustive understanding of the biology of plants to this forum. I have, however, brought forward a number of factors and possible influences relating to the variety of colors in cannabis. Genetics, maturity, pH, amount of light, temperature, and even available sugars can influence the color of cannabis. Some of these factors are easily controlled, others seemingly impossible; with knowledge comes ability.
Growing a variety of species in your garden is immensely rewarding in many ways, to which color can be a spectacular addition. While color will not change the plants potency or yields, it is possible to enhance the many colors in your garden naturally enhancing its beauty and the enjoyment of the diversity that cannabis gives us. For me, marijuana is a beautiful species that I will always grow and enjoy, in more ways than one.
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