Why Is My Cactus Turning White?

Cactus is a desert plant that has gained immense popularity as a low-maintenance house plant. While the cactus is generally green in color, it tends to turn white under various factors.

Why Is My Cactus Turning White?

The following are some of the common reasons which lead to the cactus turning white –

  • Sunburn
  • Temperature Trauma
  • Mealybug Infestation
  • Fungal Infections

1. Sunburn

If the cactus is shade-grown or kept in shade for a long duration, exposing it to direct, bright sunlight may cause sunburn to the plant. It causes tissue damage in the plant due to UV radiation. Thus, the cactus starts to bleach out and turn white.


Ideally, the cactus requires around 6 hours of sunlight each day. So, the sunburnt plant needs to be shifted to a place of partial shade, where it has access to adequate indirect, bright light. While mild sunburn damage can be treated, severe sunburn has more permanent effects. So, the best step is to trim the damaged parts with a sterilized knife.

2. Temperature Trauma

Cactus is highly prone to severe cold. So, if the cactus is left outdoors on a chilling night, it is likely to turn white due to frost damage. The chances of the survival of the frost-damaged cactus depend on the severity of the damage.


The cactus should be shifted indoors if the outdoor temperature drops to freezing lows. If the cactus has been damaged due to frost, the white spots would be permanent. Hence, the only solution would be to trim the affected part or let the cactus naturally recover its health.

3. Mealybug Infestation

Mealybugs are tiny pests that can cause severe damage to the cactus. They form colonies and leave behind a white residue which makes the cactus look white. They also suck on the sap of the cactus stem and cause the cactus to weaken. Hence, a mealybug infestation needs to be treated immediately.


The most effective treatment is to spray the plant with diluted rubbing alcohol. However, other relevant fertilizers can also be used for spraying to remove the mealy bugs. This treatment needs to be repeated for a few weeks to ensure that there is no re-infestation of the pests.

4. Fungal Infections

Fungal attacks are very common in cactus. It is caused due to spores blowing in the air , high humidity, and overwatering the cactus. Fungal attacks are generally not deadly unless it affects the roots. It causes a whitish layer to form on the cactus, making it seem white in appearance. However, some fungal infections such as root rot or crown rot can be deadly for the cactus.


In case of a fungal attack, the roots and stems must be checked to ascertain the extent of the damage. The affected parts must be detached from the main plant using a sterilized knife. The cactus should also be treated with the relevant fungicide. The cactus should be kept isolated from other plants until the infection has healed to ensure that the infection does not spread. Finally, the cactus must be re-potted with fresh, sterile soil to minimize the chances of re-infection.

So, these are some of the steps that could help you nurture a whitening cactus back to health.

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