Robert Bergman

January 11, 2017

You have probably heard of purple marijuana before, or maybe you even saw it for yourself. If you are a marijuana grower, you might even be curious about how to accomplish that impressive purple hue yourself.

In this article, we discuss ways to grow purple marijuana — as well as how not to grow purple weed.


Why does purple marijuana exist?

It’s important to note where purple marijuana comes from. Until fairly recently, examples of purple marijuana were always marijuana plants that had been growing outside under fairly cold conditions.

This could happen to many different strains of marijuana, and was before strains were specifically bred to more easily allow the purple pigments to come out under less trying environmental conditions.

It all comes down to something called anthocyanins, which are pigment molecules that have red, purple, or blue colors (which depends on how acidic they are). Therefore, strains that have a higher level of anthocyanins are more likely to turn purple — if grown correctly.

Purple Marijuana
Purple Marijuana

Pigments in plants serve an evolutionary purpose. Bright colors (including purple) attract more insects to help with the pollination process, and green chlorophyll actually captures more sun energy than other colors.

Many informed growers wonder why people prefer to grow purple marijuana. If you have done your research or have ever growing marijuana before, then you’re probably already aware that exposing a marijuana plant to colder temperatures is likely to actually reduce the amount of THC found in its buds, since the conditions aren’t exactly ideal.

Nonetheless, people prefer to buy purple weed and will even pay more for it — little do they know, the THC content is likely lower than the less expensive green marijuana.

How to grow purple weed

If you want to put in the extra effort to get purple cannabis, there are some steps you can take — but they must be done carefully. First of all, it starts with choosing the right seeds.

Marijuana strains that grow into purple plants have a high anthocyanin content. Anthocyanin is a type of pigment, the same that is responsible for other produce to be purple, such as blueberries and eggplant.

How to grow purple marijuana?
Grow room with purple marijuana

Once you have purchased marijuana seeds that have the right genetics, your next step has to be controlling the temperature. The key to doing this well is understanding how chlorophyll and anthocyanin interact and work at different times throughout the year.

Towards the end of the growing season, the green pigment found in chlorophyll begin to break down, and the anthocyanin is able to dominate. Depending on the strain, it can cause your marijuana plant to turn yellow, blue, gold, or purple.

Tip: make sure to download my free Grow Bible for more information about purple cannabis

You can manipulate this by changing the temperature in your grow room to mimic fall temperatures. To do this, wait until the flowering stage and then keep the temperature lower during the nighttime cycle of your grow room. Keep the temperature lower than 50 degrees Fahrenheit. Do this consistently, every night, and you should start to see purple coloring a couple of weeks before the harvest.

How not to grow purple marijuana

It is a common misconception that depriving your marijuana plants of the oxygen they need will actually turn your plant that purple color.

Others say the same thing about depriving your plants of carbon dioxide or other gasses. We can tell you that this is not the case, and it’s never a good idea to deprive your marijuana plants of any of the essential elements that they need to stay healthy.

marijuana burnt brown
Plant burnt brown by overloading it with nitrogen

Others suggest that overloading your marijuana plants with nitrogen is the way to accomplish the desired shade of color. This is even less true, unless you prefer your plants to be a burnt brown, as the nutrient burn as a result of too much nitrogen will almost certainly occur (and your plant’s color won’t even come close to purple).

Some marijuana growers prefer to “cheat” by actually dying their plants with purple food coloring. While this might indeed result in purple cannabis, this is not the “true” way to grow a purple-colored marijuana plant.

One last bad way of turning your marijuana plant purple is messing with its light cycle, growing medium, or the amount of water you are feeding it. These methods simply won’t work, and will only cause your otherwise healthy plants to become unhealthy, leading to a smaller yield (that isn’t even purple).

Best purple weed strains

While any strain of marijuana could turn purple if the conditions are cold enough (without harming the plant, of course), now that there is a specific interest in purple plants, people have been breeding marijuana so that strains with higher levels of anthocyanin are now available.

Purple Haze strain
Purple Haze strain

These strains include Blueberry, Blue Cheese, Haze Berry, Northern Light, Bluematic, and Purple Haze, although there are even more strains out there available for growers.

Thanks for reading. Want to start growing yourself? My free grow bible is a great place to start.


The founder of I Love Growing Marijuana, Robert Bergman, is a marijuana growing expert that enjoys sharing his knowledge with the world. He combines years of experience, ranging from small-scale grows to massive operations, with a passion for growing. His articles include tutorials on growing... [read more]


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  1. By claude

    ,06 Sep 2016
    your shipping from what contry
  2. By martin

    ,16 Jan 2019
    I grow in a basement roughly 65°, year round,l get a lot of purple buds,o.g.p diesel,

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