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How to Grow Black or Purple Cannabis Buds

Purple cannabis holds a special allure for growers and smokers.
A$AP Rocky helped make “purp weed” trendy with his song “Purple Swag”. Purple Weed has become very sought-after and most growers have fantasized about growing colorful buds at home.

What Makes Purple Cannabis so Cool?

In a world where there are thousands of different cannabis strains, colorful buds stand out as they are much rarer than green nugs. That being said, it’s not just about their looks. Although bag appeal is important, purple flowers can also have a different smell and taste. Purple Laotian weed tends to have unique berry/chocolaty aromas for instance. Likewise, black Afghan plants often produce a very earthy/nutty smell and taste. Ironically that is what gave purple strains their bad reputation back in the day. Several Dutch purple varieties bred for mold resistance would have a very harsh earthy taste. Therefore, many smokers used to stay away from purple weed. Nowadays however, purps have come a long way and there are many tasty purple strains out there.

What Makes your Cannabis Plants Turn Purple, Red or Black?

Plants produce an amazing variety of pigment molecules, even more than animals. Weed plants make multiple pigments but chlorophyll is usually the dominant one. Chlorophyll not only helps plants photosynthesize but it is also what gives them their green color. Most cannabis plants remain green throughout the flowering cycle because chlorophyll remains the dominant pigment up until the harvest.
Whenever Chlorophyll is lacking, plants can use other pigments such as anthocyanins to photosynthesize. Whereas most plants use chlorophyll to absorb all wavelengths from the sun except the green ones, those using anthocyanins absorb all wavelengths except the purple ones. That is what gives purple plants their purple color. Likewise, there are a multitude of other pigments so cannabis plants can turn purple, red, black or even pink!

Purple Calyx Closeup
Venus Blue closeup by @_seshata

What Parts of the Plant can Change Color?

Pretty much every part of a cannabis plant can change color:
The stems, the leaves (Both fan leaves and sugar leaves), the bracts (AKA calyxes), the stigmas (AKA pistils) and even the trichomes!

Purple cannabis trichomes are quite rare and hashish made with those has a unique dark purple color.
Some cannabis plants only partially change color.
For example, some have purple leaves whereas their flowers remain completely green and vice-versa.
Similarly, the famous North Indian Red Stem Landrace displays gorgeous dark red stems while the rest of the plant remains green.

Ways to Make Your Weed Colorful

Although some nutrient deficiencies can make your cannabis somewhat purple, that ain’t gonna cut it. There are only 2 proven ways to make your weed colorful.

1-Choose the Right Genetics

Some strains will stay green no matter what you do whereas others will display some beautiful colors even if you don’t do anything about it. Most cannabis varieties have not been bred for colors so the most important step is to start with a colorful strain.
Cannabis strains such as Frosty’s Purple Freak or Star Pupil will turn purple under any temperature. No cold needed for them to put on a show!

2-Cold Temperatures

If a plant is genetically predisposed to change color, cold temperatures at night will help reveal it.
Although some plants turn purple regardless of the temperature, most need lower night-time temperatures during the flowering phase. Cold temperatures cause chlorophyll breakdown and spur anthocyanin production.
Dropping the night temperature below 66° F/ 19° C will help you maximize color.

LEDs also tend to bring out colors. This could be due to the fact that they are much cooler than HIDs or because or their specific light spectrum. The exact reason has yet to be determined…

Inversely, cannabis breeders looking to create a new stunningly colorful strain need to keep their night temperature warm. Selecting the plants that turn purple at warm temperatures, generation after generation, leads to the creation of a consistently colorful strain.

You now know why cannabis can sometimes be colorful and how to cause your plants to be that way. Thank you for reading and have a colorful day!