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Cactus Care - Cactus en ligne

Cactus Rot Survival Guide

Cacti are plants valued for their resistance and low care requirements, making them ideal houseplants for both novice and experienced gardeners. Yet even these very resilient plants can fall victim to a common and potentially fatal problem: rot. In this article, we'll explore the causes of cactus rot as well as how to identify it, prevent it, and treat it if your cactus is affected.

Cactus Rot - Cactus en ligne

How does rot develop on cacti?

Rot in cacti is caused by a bacterial or fungal infection that spreads through the plant tissues. This phenomenon generally occurs when the cactus is exposed to too high a level of humidity, which creates an environment conducive to pathogen growth. Rot can affect any part of the cactus, from the roots to the tip, which can lead to the death of the specimen if the problem is not dealt with quickly.

How to identify rot

Recognizing the first signs of rot is crucial to successfully saving your cactus. Stay alert for these symptoms:

  • Mushy spots: These can appear anywhere on the cactus and are often the first signs of a rot problem
  • Discoloration: Soft areas will lose their color and become yellow, brown or black.
  • Shrinking: Severely affected areas of the plant may shrivel and even fall off.
  • Bad smell: When a large part of the cactus rots, a bad smell can escape. It is very likely that it will be too late to save it at this stage.

The causes of rot on your cactus

Cactus Rot - Cactus en ligne

Several factors can cause your cactus to rot, but most are related to water which creates an environment conducive to bacteria and fungi:

  • Overwatering: Cacti are among the plants that require the least watering. Although it is repeated as often as possible, overwatering remains the most common cause of rot.
  • Poor drainage: Using potting soil that retains too much moisture or a pot without a drainage hole can prevent the roots from drying properly.
  • Humidity too high: Excessive humidity over a prolonged period can lead to rot.
  • Physical damage: Cuts or other physical injuries to your cactus are entry points for pathogens.

How to prevent rot in cacti?

Prevention is the key to keeping your cacti from rotting! Here are some tips and tricks to keep them looking their best:

  • Proper watering: Make sure the potting soil dries completely between waterings! In doubt, it is always better to wait a few more days.
  • Well-draining potting soil: Choose a potting soil specially designed for cacti and succulents. This type of potting soil is light and provides good drainage.
  • Pot with drainage hole: In the same vein, always use a pot with a drainage hole large enough to let water drain easily and avoid accumulation at the bottom of the pot.
  • Humidity level: Choose a well-ventilated space for your cacti to prevent humidity from being too high.
  • Handling and repotting: Handle your cactus with care, especially when repotting, to avoid physical injury. Make sure any cuts or broken stems are completely dry and healed before replanting.
  • Fungicides or antibacterial products: If necessary, it is possible to apply a fungicide or an antibacterial to prevent the proliferation of rot. However, these products are not designed to treat rot once it has taken hold.

How to treat a rotten cactus?

If you notice signs of rot on your cactus, you need to take action quickly:

  1. Remove affected areas: Using a clean knife, cut away rotten tissue. Make sure to remove all the brown and soft parts.
  2. Let dry: A few days of drying will be necessary so that the cuts are well healed. This will help prevent rot from spreading.
  3. Plant in new potting soil: If you had to cut off a significant portion of the cactus, for example if the rot was at the base of the trunk, replant the plant in new potting soil for cacti and succulents.
  4. Monitor carefully: After treatment, watch closely for signs of recurring rot. Adjust your care routine accordingly.


Having to deal with rot on your cactus can be a challenge, but with good know-how and rapid intervention, it's not the end of the world! By knowing how to recognize the first signs of rot, understanding what causes it and following prevention and treatment guidelines, you will have everything you need to help your cacti thrive.

Healthy cacti will bring their unique beauty and a touch of resilience to your spaces. Stay proactive and attentive to their needs and you will be rewarded with vibrant, thriving plants in your home.

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Cactus en Ligne Team ∙

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