Why Do Some Cannabis Plants Turn Purple?

Have you ever looked at cannabis plants before they are harvested, dried, and cured? If you have, you would agree that there are some very exotic and beautiful varieties of cannabis, such as purple buds. However, you may find yourself wondering why some plants take on a purple hue. If so, let us set the record straight, since inaccurate information surrounding these enticing purple plants can still be easily found. 

When people talk about purple cannabis, you may picture something in your head that doesn’t quite match reality. Purple-hued cannabis can present itself in lighter and darker varieties, some of which may even appear black. Despite the discrepancies in hues, purple cannabis is no less impressive than it sounds.

Before we get into why the cannabis community has fallen for purple buds, we first need to explore why these buds take on their unique tinge.  

What is Purple Weed?

Purple weed categorizes a variety of cannabis strains (breeds of the plant cannabis sativa) characterized by distinctive purple or violet hues on the plant’s flowers, leaves, and stems. Some people are devoted fans of purple strains, with rumors abound that purple cannabis is “superior” in quality or perhaps even produces a “better” high.

However, despite the hype, there is no evidence that these strains contain any special high-enhancing or medicinally significant compounds that other cannabis plants do not. Namely, purple cannabis strains do not necessarily have their own unique cannabinoid or terpene concentrations that make these strains radically different from green strains.

Most likely, people who report increased benefits from purple weed may just prefer the effects provided by strains that also happen to be purple, which are often Indica strains (though not every strain of purple weed is an Indica). Thus, devotees of purple cannabis varieties often report therapeutic benefits that are effective at treating conditions like chronic pain, anxiety, and insomnia. Although they are good qualities for cannabis to have, these benefits should not be attributed to some purple magic contained in these colorful buds.

What Makes Weed Plants Turn Purple?

Simply put, cannabis can turn purple due to high quantities of compounds known as “anthocyanins.” Anthocyanins are a class of water-soluble compounds responsible for red, purple, and blue hues present in many of the fruits and vegetables that we eat, as well as in certain cannabis strains. In cannabis plants, the compound can turn the cannabis leaves and buds into a variety of purples and blues, which may even appear dark green and black. 

Anthocyanins belong to a phytochemical group known as flavonoids, which can also be found in cereals, teas, and nuts. The cannabis plant also has a high quantity of two chemical groups known as cannabinoids and terpenes, and trailing shortly behind these cannabinoids and terpenes in terms of quantity is the flavonoids. 

Research published in 2004 revealed that anthocyanins may enhance the “health-promoting qualities” of the substance it’s in. This could account for why the purple buds have gained popularity in the cannabis community, aside from the fact that they are beautiful to look at too. 

Anthocyanins have been used in traditional herbal medicines for many centuries by cultures including Native Americans, Indians, Europeans, and the Chinese. These herbal medicines, rich in anthocyanin, were often derived from dried leaves, berries, storage roots, and even seeds. The compound was used as a treatment for a variety of ailments and conditions ranging from hypertension, liver disorders, and bladder problems to the common cold and infections. 

Reports of anthocyanins’ health benefits even include improvements in vision and the circulation of blood. However, despite these medicinal benefits, researchers are unsure as to whether the apparent health benefits are due to the compound itself or whether it is due to the synergistic interactions between anthocyanins and the other compounds found in the plants. 

How Does Cannabis Get Its Color?

Factors such as pH levels, temperature, and light will ultimately influence how the anthocyanins will impact the actual pigments of the plant. 

Acidic conditions are considered to have a low pH, while alkaline conditions are considered to have a high pH level. Lower pH levels are likely to bring out varieties of red, while higher pH levels will bring out varieties of blue/purple. 

You need to choose the right strain since genetics determines anthocyanins. The varieties of the purple hue in some cannabis buds are dependent on the concentration of anthocyanins circulating throughout the plant. 

As stated before, the cold breaks down chlorophyll, which then allows the colorants from the anthocyanins to show. Be sure to avoid damaging your plant with too much cold. If you are trying to get your plant to turn colors, note that colder temperatures cause a chlorophyll breakdown, providing plants with their green coloring. By breaking down the chlorophyll, the plant is then allowed the opportunity to display the hues it’s been hiding. However, the quantity of anthocyanins needs to be high in order for any color to come through at all, and this will be determined by the genetics of the plants. Thus, getting beautiful purple plants requires a perfect combination of genetics and environmental factors. 

Note that the cannabis plant does not turn purple due to being stressed. If you try to force the change of color by depriving the plant of nutrients, it will become sick and die. 

Myth or Fact?

What Are The Best Purple Weed Strains?

Many cannabis strains are more purple in color. Some of them are so well-known for their color that it becomes part of their name, such as: 

• Granddaddy Purple
• Purple Haze
• Critical Purple
• Purple Kush
• Purple Cheese
• Strawberry Bliss
• Purple Trainwreck
• Strawberry Cough
• Purple Urkle
• Fruity Pebbles

Is Purple Weed Better Than the Rest?

Current research suggests that although anthocyanins may enhance certain medical benefits, there is not enough understanding of these compounds to definitively state that purple buds are better than green buds.

What we do know is that purple buds are more exotic and attractive to cannabis consumers and that many consumers claim to experience more potent effects from purple buds. However, it is important to keep in mind that professionals even recommend against setting the hue of a plant as your criteria for selecting which strain to consume, as some suppliers will sometimes use dyes to change the hue.

Thus, you are still better off researching the terpene and cannabinoid content of different strains to decide which is the best fit to match your preferences and needs. Overall, the lovely buds of purple weed, while attention-grabbing and enticing in appearance, do not seem to provide superior benefits over green strains of cannabis that do not contain pigmented anthocyanins. 

Frequently Asked Questions

Why is my cannabis plant turning purple?

Cannabis plants turn purple due to the presence of flavonoids called anthocyanins, which are pigments produced by the plant in response to environmental conditions such as cooler temperatures, but genetics are also involved in certain plants’ tendency to take on purple coloration. 

What does it mean when a weed plant turns purple?

A cannabis plant produces anthocyanins and turns purple as a consequence of a variety of environmental and genetic factors, such as temperature fluctuation or the particular strain of cannabis you are growing. Stress does not turn the plants purple, so there’s no need for alarm if your plant has taken on some of this coloration.

Why do trichomes turn purple?

Trichomes are normally characterized as being clear, white, or amber in color, but weed strains genetically predisposed to produce more of the anthocyanin pigment may appear purple. This can make it difficult to determine when the flowers are ready for harvest, as trichome color is used to determine whether the flowers have fully developed their potency. 

What does it mean when the cannabis leaves change color to yellow, red, purple, blue, or pink?

Certain color changes in cannabis leaves, such as yellowing or taking on spots, can indicate plant stress due to environmental conditions or infection. Specifically, yellow cannabis leaves typically result from overwatering or nutrient deficiency. On the other hand, colors like red, purple, blue, or pink are often caused by the presence of anthocyanins, which can appear as a result of cooler temperature, soil acidity, or individual plant genetics, and such coloration should be no cause for alarm in an otherwise healthy cannabis plant.

What was the first purple weed strain?

Purple #1 is recognized as the “original” purple cannabis strain. It was cultivated in the 1980s and featured a 50/50 Sativa/Indica cross.

Are there purple Sativas?

While purple coloring is more commonly associated with Indica or Indica-dominant weed strains, there are also Sativa varieties that display the anthocyanins’ iconic hues, such as Purple Thai or Purple Haze.

Is purple weed better than other types of cannabis?

Purple weed is sometimes coveted and championed for its unique appearance and potential antioxidant properties contributed by the anthocyanins, but a strain’s therapeutic effects are more largely attributable to a strain’s particular cannabinoid content and terpene profile. Some purple weed enthusiasts merely prefer purple cannabis strains for their beauty, and others seem to just prefer the effects offered by certain strains that happen to be purple. 

This article was originally written in 2020 by Chane Leigh and updated in January 2025.