Why Is My Cactus Turning Purple?

Cactus is a desert plant that has become an essential house plant due to its exotic appearance and resilient nature. Sometimes the cactus plant tends to turn purple. Some cacti, like prickly pear, turn purple due to the bearing of fruits. However, in other cacti, it is a sign of stress. The plant turns purple while trying to adapt to stressful conditions. Hence, added measures need to be taken to ensure that the cactus is not damaged.

Why Is My Cactus Turning Purple?

The following are some of the common reasons which lead to a cactus turning purple-

  • Excessive Sunlight
  • Lack of Nutrients
  • Improper Watering
  • Temperature Stress
  • Cactus Cyst Infection

1. Excessive Sunlight

If the shade accustomed cactus is exposed to direct sunlight for long hours, the stems produce UV protective stress compounds called Anthrocyanins, which have pigments that cause the plant to turn purple.


The scorched plant needs to be moved to a place where it receives bright, indirect sunlight for at least 6 hours a day.

2. Lack of Nutrients

A wilting, purple cactus is a sign of deficiency in essential macronutrients, especially magnesium. This may happen due to poor quality potting soil or the unsuitable size of the pot.


Adding Magnesium enriched fertilizer or diluted Epsom salt would likely solve the issue. Otherwise, the plant needs to be potted in a bigger tub with fresh, fertile soil to enable the roots to properly absorb the nutrients.

3. Improper Watering

Overwatering the cactus can cause the plant to turn mushy and purplish. Stagnant water can also cause root rot, which results in the inability of the plant to absorb nutrients.

Similarly, an under-watered cactus can turn brittle and purple. This is because a very dry environment lacking adequate moisture can trigger stress in the plant.


Overwatering can be checked by ensuring proper drainage in the pot. Allow the excess water to drain off before adding any more water to the plants. If there is root rot, the affected roots must be cut off from the main root, and the plant must be treated with fungicide before being replanted with fresh, fertile soil.

An underwatered plant must be adequately moistured to nurture it back to health. Further, measures such as using a humidifier or placing the tub on a shallow pan of water can be used to ensure that the moisture remains adequate.

4. Temperature Stress

Cactus, when subject to either extreme heat or cold, effectively discolors to a purplish shade. However, this only becomes something to worry about when the plant is put through extreme temperatures for 6-8 weeks.


The cactus must be placed away from places like windows, heating vents, open doors to minimize temperature fluctuations. Avoid black plastic pots and go for clay ones instead.

5. Cactus Cyst Infection

An infection of a pathogen called a cactus cyst could also be the reason for your cactus turning purple. It generally happens when the cactus is planted in infected soil. It causes stunted growth, wilting leaves and root spores.


Prevention is the best cure in this case! As the cactus cyst is very hard to treat and once infected; the plant would likely have to be discarded. To prevent this, the cactus must be planted in clean, sterilized soil.

So, these are the solutions to nurture your purple cactus back to health.

Leave a Comment