Why Is My Cactus Turning Red?

Cactus is a succulent house plant adapted to survive in harsh conditions. In the process of growth, the spines of some cacti often tend to turn red. It is a natural process. There is no need to worry about it.

However, when the leaves of cactus plants turn red, it is a cause of concern. It signifies that the cactus is undergoing stress. Hence, some measures need to be taken to ensure that the cactus comes back to its original color.

Why Is My Cactus Turning Red?

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

  • Extreme Temperature Fluctuations
  • Inappropriate Sunlight
  • Lack of Magnesium
  • Inadequate Moisture

1. Extreme Temperature Fluctuations

When the cactus is subject to extreme fluctuations in temperature, there is stress in the plant. It causes the cactus to release a stress pigment called anthocyanins, which gives it a reddish color. It happens when the cactus is placed near a heating vent or a refrigerator.


In general, cacti prefer temperatures from 10° – 29° Celsius. This means the cactus needs to be kept away from things radiating extreme heat or cold. Further, ensure that it is kept away from open areas in extreme winters and summers.

2. Inappropriate Sunlight

When the cactus comes in contact with sudden, direct sunlight for long hours, it faces stress. The plant produces stress pigments to combat the UV rays . These pigments cause the plant to turn red.

Similarly, a lack of adequate sunlight may cause similar stress; thus, the plant turns red.


Cactus needs 6 hours of bright, indirect sunlight and light shade for the rest of the day. So, the ideal solution would be to place the plant near a south-facing window or in a place where there is an adequate balance of sunshine and shade.

3. Lack of Magnesium

Magnesium plays an essential role in helping the plant with photosynthesis. If there is a lack of magnesium, this process tends to slow down. This causes the cactus to turn pale red and its leaves to wilt.


Generally, the cactus gets the macronutrients from the soil. Hence, if there is a deficiency, the plant must be re-potted with fresh, fertile soil. Further, magnesium-enriched fertilizers, as well as Epsom salt, should be used to nurture the plant back to health.

4. Inadequate Moisture

Underwatering the cactus may create a drought-like environment for the cactus. This causes the cactus to reduce photosynthesis, due to which the color of the cactus turns red.

Similarly, over-watering the cactus may cause stagnation of water . This causes the cactus to turn mushy and eventually gives rise to infections such as root rot. Due to such infection, the roots cannot absorb nutrients and causes the cactus to turn red.


An under-watered plant should be adequately watered to nurture it back to health. Further, measures such as placing the tub on a shallow pan of water or using a humidifier can be implemented to ensure that the moisture remains adequate.

An over-watered plant needs to be treated by ensuring proper drainage. Further, the plant should be checked for root rot. The infected root should be treated with fungicide before being planted with fresh, fertile soil.

So, these are the measures that are to be undertaken to ensure that the red cactus can be nurtured back to its original color.

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