purple weed colors

Purple Weed: How Cannabis Strains Change Colors

Who doesn’t love to see their weed plants change from green into the prettiest colors? Purple weed is a beautiful and widely known phenomenon, thanks to iconic cannabis strains as Purple Haze. But why do some cannabis plants turn purple and others don’t? Let’s find out:

Colors in Cannabis

A color is seen and perceived because light reflects on pigment. And the pigment that makes cannabis green is pretty well known: chlorophyll. Apart from the visual aspect, this pigment is recognizable by a bitter taste – found in cheaper CBD Oils for example. This plant’s green is the same substance that gives lettuce and other vegetables their green color. So we ingest enough of it on a daily base.

Though what’s really interesting, is the substance that makes weed plants turn purple: anthocyanin. Anthocyanins are a group of around 400 water-soluble pigments, belonging to the category ‘flavonoids’. After cannabinoids (like THC and CBD) and terpenes, flavonoids are one of the three most important components that make cannabis such a versatile and unique organism.

Purple Cannabis

Anthocyanins do not always manifest themselves in purple, though. Depending on the acidity of the plant, this pigment can show different colors. In acid environments these anthocyanins turn red or pinkish. More neutral acidity levels make anthocyanins show purple and alkaline environments make this pigment turn blue.

purple cannabis buds weed colors
The green’s purple: anthocyanins make cannabis buds turn purple

The word ‘anthocyanin’ comes from Greece. Where the German botanist Ludwig Marquart first discovered the pigment in 1835. He named it after anthos (flower) and kyanos (blue). Although this doesn’t mean the purple in cannabis only shows on the flowers of the plant. Even the leafs, stems and branches can show the beautiful colors of anthocyanin. But what exactly causes this to show?

Cold Nights & Genetics

The most important element causing this phenomenon, is genetics. Some cannabis strains simply produce more anthocyanins than others. Though these colors are not always visible throughout the plant’s lifecycle. Nor are they guaranteed to appear in strains like Purple Haze, Blueberry or Purple #1 when you grow them at home. As you might have experienced yourself, these strains can also grow into beautiful green specimens.

purple cannabis weed buds color
Anthocyanins become better visible when cold nights make chlorophyll break down into sugars for cannabinoid production

That is because the dominant pigment chlorophyll usually makes it difficult for anthocyanins to show. But as soon as the days turn colder, the cannabis plant starts turning chlorophyll into sugars. Sugars that can be used by the plant as energy for the production of flowers, cannabinoids and seeds. This breakdown process gives anthocyanin the chance to push through and really show its true colors.

We at Amsterdam Genetics do not stock these extremely purple coloring cannabis strains like Purple Haze. Though we do have some strains that are more probable to turn into purple cannabis plants than others. Our Blue Magic and Blue Amnesia for example are strains that are known to turn blueish under the right conditions. For more red / purple like tones, you’d be best off with our Kosher Tangie Kush.

blue magic purple weed
Our ‘Blue Magic’ is known to turn blueish / purple under the right conditions

Grow Purple Weed

So if you’re planning to grow your own purple weed, the right genetics are a good place to start. Though it’s not all you need to grow colorful weed. As we’ve stated before, an important factor in this color change is temperature. When cannabis plants turn cold, the production of chlorophyll stops; giving anthocyanins room to show its shade.

Chances are that this phenomenon is a survival mechanism for cannabis plants. Wether it is to attract pollinators like bees, or to attract more warmth with their dark color: WE LOVE IT! Don’t be shy and turn the heat down in the last weeks of the flowering stage to enjoy this spectacle in your own grow room or garden!

purple weed strains cannabis colors


Blue Monkey CBD

Our CBD strain Blue Monkey is also purple or maybe even almost black when she’s grown in the right conditions. She’s showing her true colors! This strain is more for medical use, as she contains 11.4% CBD and 0.03% THC.



Disclaimer: Local laws and legislation on cannabis cultivation and germination of seeds vary between countries and states. Amsterdam Genetics products and information are exclusively intended for use in areas where such use is fully legal. Check your local rules; do not act in conflict with the law!

CHOCOLATO cannabis strain


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