Lemon Haze and Strawberry Banana are yellow.
Blue Haze and Blueberry are blue.
Granddaddy Purple and Purple Urkle are, you guessed it, purple.
You don’t have to be a weed connoisseur to have seen the rainbow of colors that distinguishes marijuana strains. Most of us have come across vibrantly-colored flower at one time or another.
But even though you may have heard stories claiming that black cannabis is killer bud, there’s a good chance you’ve never seen it.
Well, black strains do exist. You shouldn’t be surprised if you’ve never had the chance to try black cannabis, though; the strains are fairly rare, and most only develop their trademark color under very specific environmental conditions.
Why are some weed strains black? And is black cannabis worth seeking out?
We’ll get into the full story after a brief detour that provides important background.
What Gives Plants Their Color?
Virtually all plants that depend on light for growth contain chlorophyll. It’s the pigment that allows light energy to be converted to chemical energy through the process of photosynthesis. You probably don’t remember much from science class, but you probably remember that. Chlorophyll, of course, is what gives plants (and leaves) their green color, too.
Then why do leaves turn red, yellow, and orange in the fall before they fall off deciduous trees? There are two factors involved.
One is that the leaves produce less chlorophyll as temperatures fall, and there’s less sunlight to convert to energy. Here’s the other: leaves contain flavonoids called anthocyanins — and anthocyanins are also pigments that can contribute color to a plant.
As autumn progresses and leaves contain less and less chlorophyll, the color of their anthocyanins can shine through.
Weed plants contain chlorophyll, and many also contain anthocyanins. That brings us to the color of cannabis.
The Multi-Talented Anthocyanin
Strawberries are red; blueberries are blue.
That’s not the start of a greeting card rhyme; it’s a way of pointing out that anthocyanins — which provide the trademark colors of those fruits and many others — don’t always take on the same color.
The anthocyanins in cannabis plants don’t always provide the same color to flowers, either. One of the major reasons they can take on different hues is the pH of their environment.
If you thought we were done with science, sorry about that. We have one more quick lesson (or refresher). pH stands for potential hydrogen, and it measures acidity on a scale of 1-14. 7.0 indicates that a substance is neutral, neither acidic nor alkaline. The closer the pH gets to 1.0, the more acidic it is; as it rises above 7.0, it’s more alkaline.
Weed plants grow best when the growing medium they’re planted in and the water they receive; each has a pH around 6.0. But not all growers maintain optimal conditions, meaning that changes in pH can cause buds to take on different colors once their chlorophyll content declines.
Anthocyanins are red or pink in acidic conditions, orange or purple when the pH is neutral, and yellow or blue when the pH goes above 7.0. That’s the major reason why Lemon Haze is yellow, and Blue Haze is blue, although some strains are also genetically predisposed to turn certain colors.
The vibrancy of a strain’s color is primarily determined by the amount of anthocyanins it contains, which is usually due to the plant’s genetics. However, other factors can come into play as well.
Greater light exposure causes some plants to produce additional anthocyanins, and some strains only display the full beauty of their color at specific temperatures. Increased stress, such as drought conditions, can also boost anthocyanin production.
You probably noticed that so far, we’ve mentioned cannabis that’s green, red, pink, orange, purple, yellow, and blue — but not black. Let’s do that now.
Why Is Black Cannabis Black?
You now know that a higher concentration of anthocyanins makes the color of a plant appear more vibrant. For colors like blue and purple, that means they appear darker and darker.
That happens in all plants. For example, the flavonoids are responsible for the color of black currants, black rice, and eggplants. We hear you say that eggplants are purple, not black? Well, that’s in the eye of the beholder. Some eggplants are such a deep purple that they may appear black.
That’s actually the same story for some weed strains. They may not “really” be black, but they have such a deep purple color that they’re close enough to be called black cannabis.
There’s one other factor. Some strains like Vietnamese Black are apparently genetically programmed to take on black color. And that tendency is multiplied when two “like-minded” strains are cross-bred.
It’s believed that these hybrids are likely to show a black color because they can efficiently turn the glucose produced by photosynthesis into additional anthocyanins. Examples of these “black” strains include Black Diesel, Black Widow, and Black Domina.
Bottom line: black cannabis is usually black because the plant has been grown in neutral pH conditions, it contains bountiful amounts of anthocyanins, and/or the strain is predisposed to display that color.
Is Black Cannabis More Potent?
Some people claim that black weed is the dankest you can find. That’s not necessarily the case.
The color of a cannabis plant has nothing to do with its THC content. Red, yellow, purple, and black buds can be just as potent as “normal-colored” flower because cannabinoids and terpenes have no impact on the plant’s color.
However, that’s not all there is to know about the subject.
First of all, strains like the Vietnamese Black we mentioned earlier are pure sativas known as landraces, which have evolved to be extremely potent. Their color and their potency aren’t related. They’re simply two different attributes.
Second, growers and cultivators know there’s a high demand for black weed because of its exotic reputation. Some take strains that “lean black” and cross-breed them or alter growing conditions to encourage the development of additional anthocyanins, which could highlight a strain’s dark purple or brown color.
So it’s more likely today than it used to be that the black cannabis you discover at a dispensary will be a killer strain — but that’s because it’s been bred that way, not just because of its gorgeous and unusual black color.
Black Cannabis: FAQ
Q: Isn’t there a strain called The Black?
A: Yes, and it’s definitely black in color. It’s an indica-dominant hybrid whose Canadian cultivator has kept its parentage a secret, so we don’t know what type of “black” ancestors it may have had. It’s also a strong strain with 20%+ THC content, and it’s particularly popular among medical marijuana patients who can find it.
Q: Is there any way to “turn a plant black?”
A: Only if you start with the one that has genetics conducive to it. In that case, grow it with neutral pH soil and water, give it lots of bright light, don’t give it more water than it can handle, and make sure temperature and humidity are on the low end of acceptable. Then, cross your fingers.
Khoo, H. E., Azlan, A., Tang, S. T., & Lim, S. M. (2017). Anthocyanidins and anthocyanins: colored pigments as food, pharmaceutical ingredients, and the potential health benefits. Food & nutrition research, 61(1), 1361779 .
Ogston, A. G. (1947). The definition and meaning of pH. Physiological Reviews, 27(2), 228-239 .
Casañas, F., Simó, J., Casals, J., & Prohens, J. (2017). Toward an evolved concept of landrace. Frontiers in plant science, 8, 145 .