7 Reasons for Cactus Turning Brown (Solutions)

Cacti are known for their vibrant and striking colors, but sometimes cacti can become dull and brown. Despite being a common houseplant, they are not immune to disease and damage. If you’ve noticed your cactus turning brown, it could be due to various reasons. This article will explore 7 possible causes of cacti turning brown and guide you through what steps to take next.

cactus turning brown

7 Reasons for Cactus Turning Brown

Since there could be a range of factors causing your cactus to turn brown, here are seven of the most common reasons for this issue:

1. Overwatering

Cactus plants are native to the desert and used to drought periods; therefore, it is essential to not over-water them. An overwatered cactus can succumb to root rot, making it important to ensure that the soil completely dries out between waterings.

Additionally, it is important that the pot size is chosen correctly; too large a container will hold more moisture than necessary and may result in overwatering. Select a pot size that provides enough space for the ball of the plant but no more than that. If you notice signs of brown spots or dehydration on your cactus, let it dry out before watering again.

Be mindful of how much water your cactus needs and ensure that you provide enough—but not too much—water. For further protection, avoid placing your cactus in a dish or tray that may collect extra water, and always feel the pot’s weight before watering to ensure it is not already saturated.

why is my cactus turning brown

2. Sunburn

Like humans, cactuses can become sunburned if they get too much sunlight. When exposed to the sun’s UV rays for long periods, cactuses are likely to become discolored, bruised, and even develop ”sunspots”. It is important to ensure that your cactus is in an area with plenty of indirect light rather than direct sunlight. If you have a sun-facing window, consider adding a sheer curtain or blind to reduce the amount of sunlight your cactus is exposed to.

Furthermore, if you want to move your cactus outdoors for summer, introduce it slowly and gradually increase the exposure. Similarly, when bringing it back indoors, make sure to do so gradually and avoid sudden shifts in light intensity.

3. Nutrient Deficiency

If your cactus is lacking in certain nutrients, this is likely to result in parts of it turning brown or yellow. Some common deficiencies include magnesium, calcium, iron, and potassium. It is important to ensure that your cactus receives all the nutrients for healthy growth.

Soil quality is a key factor, and if your soil lacks nutrients, this can easily be resolved with a slow-release fertilizer or some compost. Additionally, you can provide a foliar spray of liquid fertilizer to help your cactus get the nutrients it needs. A regular top-dressing of compost, manure, or fertilizers will also ensure that your cactus has the essential nutrients it needs.

cactus turning brown

4. Incorrect Overwintering

Incorrect overwintering is one of the most common mistakes made by gardeners when it comes to taking care of their cacti. Incorrect overwintering can lead to the development of brown spots, a sign of rot, and the weakening of the cactus health.

During winter, temperatures drop, and moisture levels rise in the air. This creates an ideal environment for rot to develop on the cactus, as the cold and wet can cause damage to its tissues. To prevent this, it is important to ensure that the overwintering temperature remains above 5°C (41°F). It is also important to keep the cactus dry, as too much humidity can lead to rot development.

The overwintering location is also important in ensuring your cactus’s health. The ideal spot should be dry, dark, and cool; a basement or garage would work well. Keep the pot in a gravel tray, allowing water to drain away from the roots, and keep the pot off the ground.

Finally, cacti should be monitored regularly during the overwintering period. Check for rot, pests, and other diseases, and provide treatment if necessary. Any damaged parts of the cactus should be removed promptly for the plant’s health. By taking these steps, you can ensure your cactus will remain healthy throughout the winter and come out of hibernation with all its strength intact.

5. Pests & Diseases

Brown spots on cactus plants can indicate that fungi, pests, or diseases afflict them. If the plant is firm and healthy to the touch, it may be a fungus issue. You can prevent additional brown patches from forming by using an appropriate fungicide. Unfortunately, the spots will remain visible even after treatment. Signs of a fungal infection include small holes or lesions that resemble spots caused by cool or wet conditions; however, these won’t lead to the death of the plant if monitored properly.

Another potential cause of hard brown spots on a columnar cactus is an infestation of scale insects. These insects extract the juices from the plant, resulting in hard, discolored areas. To remove them, use an insecticide or try to drown them with a cotton swab soaked in 70% alcohol. After doing this, you may need to scrape the scale off the spot carefully. If you find this too difficult, consider seeking professional help.

Your cactus may show signs of spider mite infestation, characterized by thin webbing. To address this, it is important to take immediate action by mixing half alcohol and half water in a spray bottle and spraying the affected area. Removing the mites quickly is essential for preventing further damage to your cactus.

cactus turning brown

6. Cactus Rot

Cactus rot is a common issue affecting any part of the plant from the base to the tip. It is often caused by fungi, diseases, or moisture entering the plant through an open wound on the leaves or stems. Usually, signs of dry rot don’t appear until the cactus begins to brown at the apex.

Root rot is caused by overwatering, poor drainage, and high humidity levels. Cacti should not be watered to prevent root rot until the soil is completely dry. Water should also be applied sparingly, and drainage holes should be provided to ensure any excess moisture is drained away.

If the plant does become infected with root rot, it can be treated by removing the affected part of the root, allowing the remaining parts to dry out, and then replanting it in fresh, well-draining soil. In extreme cases, a fungicide may be necessary to eradicate the infection completely.

7. Corking

As cactus plants mature, they may display brown discoloration along the stems and base. This phenomenon is known as ”corking” and serves an important purpose: it strengthens the stem and provides additional support for the plant. A fairly typical cactus bush will exhibit the quick appearance of a solid, bark-like, or brown membrane only a few centimeters above the soil. While this process occurs naturally in older cacti, there’s no need to worry; it is simply part of the plant’s aging process.

cactus turning brown

Why Is My Cactus Turning Brown and Soft at The Bottom?

The browning and softening of the base are usually caused by overwatering or too much humidity. Cacti are prone to root rot when exposed to too much moisture for extended periods. Moreover, their water reserves run out if they go too long without water. You can notice them softening at this point.

The plant may also turn yellow if it is very dry or lacks water. If the plant is still alive, you should stop watering it and allow the soil to dry out completely before attempting to repot the cactus. If you find any soft or mushy spots, carefully remove these affected parts with a sterile tool. If it is too far gone, dispose of the plant and start over with a new one.

How Do You Fix a Cactus That Turns Brown?

If the cactus turns brown, the cause can be identified by examining the environment and symptoms. If it’s due to over-watering or humidity, try to reduce the amount of water and ensure good air circulation. If there are signs of pests or fungi, you can use an insecticide or fungicide accordingly.

In case of sunburn, move the cactus to a shaded area and adjust the light exposure slowly. If your cactus is turning brown due to root rot, prune the affected parts, repot it in fresh soil, and water it only when it is completely dry.

Can a Brown Cactus Turn Green Again?

If the cactus is still alive, it can be revived and made turn green again. Start by examining the environment and symptoms and correcting any issues affecting the cactus. Next, repot the cactus in fresh soil and adjust its water intake accordingly. Finally, provide it with enough light and monitor it for any signs of growth. You can help your cactus turn green again with the right care and attention.

Should I Cut off Brown Cactus?

If the brown parts of your cactus are dry and brittle, it may be beneficial to cut them off. This will help prevent further damage to the plant and help it focus its energy on healthy, green parts. However, make sure to use a sharp, sterile knife when pruning and avoid cutting into healthy parts. If the brown parts are still soft, it is best to wait until they become dry and brittle before attempting to remove them.


The discoloration of a cactus can be attributed to various environmental factors. An extreme temperature, either too hot or too cold, and an excess of light or water absorption could all cause discoloration. If these conditions are ruled out, there may be an infestation of pests or fungi causing the discoloration. Lastly, the cactus may be discoloring due to a natural aging process.