What Causes Cannabis to Turn Purple in Color?

Here we explore what causes cannabis to turn purple in color. We’ll discuss the genetics, environment, and nutrition that can produce this effect.

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The Science of Cannabis Colors

Cannabis colors can range from vibrant greens to deep purples, and everything in between. So, what causes this wide range of colors? The answer lies in the science of cannabis colors. Cannabis colors are caused by a variety of pigments, including chlorophyll, carotenoids, and anthocyanins.

The role of anthocyanins

Anthocyanins are plant pigments that are responsible for the red, blue, and purple colors of many fruits, vegetables, flowers, and even cannabis. In plants, they serve several functions, including protecting the plant from UV radiation and attracting pollinators. Cannabis plants are unique in that they can produce anthocyanins even when they don’t need to!

While the role of anthocyanins in cannabis is not fully understood, it is thought that they may play a role in UV protection, temperature regulation, or attractant for pollinators. Regardless of their function, anthocyanins are responsible for the stunning colors of purple cannabis strains.

The production of anthocyanins is affected by several environmental factors, including temperature, light exposure, nutrition, and even genetics. For example, some strains of cannabis are more likely to produce anthocyanins than others. Cannabis growers can encourage the production of anthocyanins by exposed their plants to cooler temperatures (around 60-75 degrees Fahrenheit) during the vegetative stage and limiting nitrogen fertilization.

If you’re lucky enough to come across a purple cannabis strain, you may be curious about its effects. Unfortunately, there is no scientific evidence to suggest that purple cannabis strains have different effects than other strains of cannabis. However, many people believe that purple strains tend to be more relaxing and provide a “body high” sensation.

The role of carotenoids

Cannabis plants produce carotenoids, which are responsible for their yellow, orange, and red tones. These molecules are also found in other fruits and vegetables like carrots, tomatoes, and peppers. The human eye sees carotenoids as red or orange, but the molecules can actually come in a wide range of colors. When it comes to cannabis, carotenoids typically fall into two categories: xanthophylls and carotenes.

Xanthophylls are yellow pigments that include lutein, zeaxanthin, and cryptoxanthin. These molecules are common in fruits and vegetables like oranges, strawberries, and corn. Carotenes are red or orange pigments that include beta-carotene (the molecule that gives carrots their color) and lycopene (the molecule that gives tomatoes their color). Cannabis plants produce both xanthophylls and carotenes, but carotenes are less common than xanthophylls.

In general, cannabis strains with more xanthophylls will be yellow or green, while strains with more carotenes will be orange or red. However, there is some overlap between these two groups of molecules. For example, beta-carotene is a carotene that can also be found in xanthophylls. This means that some cannabis strains may be yellow or green due to their high beta-carotene content.

The Conditions that Cause Cannabis to Turn Purple

As cannabis growers know, the color of the cannabis plant can change during the flowering stage. One of the most striking colors that cannabis can turn is purple. While it might be tempting to think that this is caused by some kind of mutation, it’s actually the result of a few different environmental conditions.


While cannabis plants can turn purple without the help of any outside forces, most of the time, this change in color is a result of something called anthocyanin. This naturally occurring pigment is found in lots of other fruits and vegetables (think blueberries, blackberries, andeggplants), and it’s what gives these plants their distinctive colors.

Cannabis plants produce anthocyanin when they are exposed to colder than usual temperatures – usually around 55 degrees Fahrenheit or lower. This can happen either when the weather outside dips into these cooler temperatures or when growers manipulate the temperature in their grow rooms to induce this change.

In addition to temperature, cannabis plants also need a lack of nitrogen and a higher than usual concentration of phosphorous for anthocyanin to form. For this reason, growers will often change up their fertilization schedules when they want their plants to turn purple.


One of the most common reasons that cannabis plants turn purple is due to stress. Stress can be caused by a number of different factors, including nutrient deficiencies, temperature changes, light changes, and more. When a plant is stressed, it produces chemicals called anthocyanins as a way to protect itself. These chemicals are what give plants their purple color.

Nutrient deficiencies

Cannabis plants can turn purple for a variety of reasons. Sometimes it’s because of a nutrient deficiency, other times it’s because of the cold weather. But whatever the reason, purple cannabis is definitely something that gets growers excited.

One of the most common reasons for purple cannabis is a phosphorus deficiency. Phosphorus is one of the key nutrients that cannabis plants need in order to grow and produce buds. It’s also responsible for the color of the leaves. When there’s not enough phosphorus in the soil, cannabis leaves will start to turn purple.

Other nutrient deficiencies can also cause purple leaves, including magnesium and nitrogen deficiencies. But phosphorus is by far the most common culprit.

Purple leaves can also be caused by exposure to cold temperatures. When the temperature drops, anthocyanins (pigments that give plants their color) are produced in greater quantities. This is why many plants, including cannabis, turn red, orange or yellow in autumn. But if the temperature falls low enough, anthocyanins will actually turn leaves purple.

How to Prevent Cannabis from Turning Purple

Cannabis plants can turn purple for a variety of reasons, including stress, genetics, and temperature changes. While some growers consider purple cannabis a novelty, others strive to prevent their plants from turning this color. Let’s learn more about how to prevent cannabis from turning purple.

Proper nutrition

To prevent your cannabis from turning purple, you will need to make sure that it is getting the proper nutrition. The most important nutrient for preventing purple cannabis is calcium. Calcium helps to build strong cell walls, and without it, your cannabis plants will be more susceptible to pests and diseases. Make sure to fertilize your plants with a calcium-rich fertilizer, and if you are growing in soil, add some crushed eggshells to the soil as well.

In addition to calcium, your cannabis plants will also need other nutrients such as nitrogen, phosphorus, and potassium. These nutrients are essential for proper growth and development, and they can be found in most commercial fertilizers. However, if you want to give your plants a boost, you can add compost or manure to the soil before planting.

Proper lighting

The main reason purple strains exist is due to the pigments that are in their leaves. In order for these pigments to develop, however, the plant needs to be properly hydrated and contain a high concentration of anthocyanins. Additionally, the plant must be exposed to cooler than average temperatures during its flowering stage; this allows for the proper development of the anthocyanins.

Since most growers do not have controlled environments, they must take extra care during the flowering stage to ensure that their plants are exposed to these conditions. One way to do this is by providing your plants with proper lighting. The light from the sun contains all of the colors of the visible spectrum, but blue and violet light waves are shorter than those of red and orange. This means that blue and violet light penetrate leaves more deeply than red and orange light.

As a result, if you want your purple cannabis strain to develop its full color potential, you should expose it to lots of blue and violet light. This can be done by using LED grow lights or special HPS bulbs that emit more blue and violet light than standard HPS bulbs. You can also use compact fluorescent bulbs (CFLs) or metal halide (MH) bulbs, but these will not produce as much blue and violet light as LEDs or special HPS bulbs.

In addition to providing your plants with proper lighting, you must also make sure that they are getting enough water and nutrients. Cannabis plants need a lot of water, especially during the flowering stage when they are producing most of their flowers (buds). You should water your plants until the soil is evenly moistened but not soggy; if the soil is too dry, the leaves will turn yellow and if it is too wet, the leaves will turn brown.

Additionally, cannabis plants need a wide variety of nutrients in order to grow and produce buds properly. These nutrients include nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), boron (B), molybdenum (Mo), chlorine (Cl), and cobalt (Co). While some growers add all of these nutrients individually to their soil or water, others prefer to use a pre-mixed nutrient solution that contains all of these nutrients in one bottle.

Proper watering

If you want to prevent your cannabis from turning purple, make sure to water it properly. The amount of water your plant needs will depend on the size of the pot, the type of soil, and the climate. In general, you should water your plants when the top inch of soil is dry. You can check this by sticking your finger in the soil.

If you overwater your plants, they may start to turn purple due to a lack of oxygen in the roots. When roots don’t have enough oxygen, they start to die, which can cause the leaves to turn purple.

To prevent this from happening, make sure you’re using a well-draining soil and not watering your plants more than they need. You may also want to consider using an air stone in your hydroponic setup to make sure the roots are getting enough oxygen.

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