The colors of cannabis are a highly debated subject with different schools of thought prevailing as to why cannabis displays different hues. Cooler temperature is just one of many factors that contribute to the color of your hemp. Long time growers can attest to the exceptional variety of colors attainable in your everyday hemp crop.
An annual plant, cannabis hemp completes its life cycle within one year, starting as a seed, then germinating, maturing, reproducing, and dying. For a large part of its life, hemp 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 hemp 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 isn’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 have colored flowers in all but the warmest grows; the colors in these flowers 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. 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, flower 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.
Some hemp strain's genetics produce pistils that can change colors. Certain nutrient formulations with a higher pH can cause these hemp plants to produce flowers with reddish pink or even magenta pistils, while the same plant grown in a lower pH will develop white pistils.
Hemp 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.
Colorful hemp can be attractive or even visually stunning, but other than white flowers glistening with shiny trichomes, hue is usually not a reliable indicator of potency. But if you are consuming your hemp orally in tinctures, oils, edibles, or capsules, you may be getting the nutritional benefits of carotenoids, anthocyanins, and other flavonoids. Anthocyanins have shown some activity at CB1 and CB2 receptor sites and may have a synergistic, or entourage, effect in conjunction with cannabinoids and terpenes.
Edited By: Joseph Jackson