Why Does Some Weed Turn Purple?

What Causes Cannabis Plants to Change from Green to Purple?

The striking purple color that cannabis plants and flowers sometimes have mirrors the imperious purple of classical times—both symbolize quality, beauty and high status, captivating with their deep, rich hues.

But what causes cannabis plants to change from green to purple?

Cannabis leaves, stems and flowers can turn purple due to a biochemical process that involves the production of anthocyanins, a type of flavonoid pigment, which gives cannabis its distinctive purple color.

This process is usually triggered by external stressors. Similar to how goosebumps are triggered by a sudden chill, temperature plays a big role. When cannabis plants experience a drop in temperature, usually at night toward the end of their flowering cycle, it can trigger the production of anthocyanins— the pigments responsible for purple colors.

However, temperature isn’t the only factor. Soil pH levels and the nutrients the plant receives can also influence whether the plant turns purple. For example, higher pH levels can boost anthocyanin production. Additionally, nutrients like phosphorus and magnesium can help bring out the color.

Not all cannabis plants will turn purple, even under the right conditions. Some strains are genetically predisposed to show purple, while others remain green.

Light exposure is another key factor. Cannabis plants that receive intense light during the day and cool temperatures at night are more likely to develop purple flowers, as the combination of light stress and cooler nights promotes anthocyanin production.

In the end, the purple color in cannabis plants is a result of genetics and how the plant responds to its environment—temperature, soil, and light—all working together to trigger the color change.