If you’ve recently noticed that your cactus is turning black, you’re probably wondering what’s going on and how to fix it. Unfortunately, there can be several reasons why this might happen, but don’t worry – we’re here to help!
*This post may include affiliate links. When you purchase items from these links, we will receive a small commission, at no extra cost to you, to help support this website. Thank you for your support! Read more ->
In this post, we’ll discuss the three main causes of cactus turning black and how to remedy the problem. So read on for information that could save your beloved cactus!
(Keep in mind, there are some cacti that are meant to be black! Find those awesome plants here)
Why Is My Cactus Turning Black?
There are three main reasons that your cactus is turning black, and those include:
- Pests (black spots)
We’ll discuss each of these in detail below so that you can determine which is causing your cactus to turn black. Then, we’ll give you some tips on how to save your cactus!
Cactus Turned Black From Rotting
The way to identify if your cactus is turning black from rotting can be if it’s the base of the cactus that’s changing color first, and if the soil feels soggy. The cactus can also be turning white or shrinking if it’s rotting.
When cacti sit in water for extended periods of time, their roots begin to rot. This can cause the entire plant to turn black and eventually die.
Caring For a Rotting Cactus
If you think your cactus is rotting, the first step is to check the roots. If they’re mushy or black, then it’s likely that the plant is beyond saving. However, if the roots are still firm and white, you might be able to save your cactus with some quick action!
First, remove the cactus from the pot and shake off any excess water or soil. Then, allow the plant to dry for a few hours before replanting it in fresh, dry soil.
Prevent in the future: Make sure that you’re not over-watering your cactus so that this doesn’t happen again. Water your cactus only when the soil is dry to the touch.
Check out our post on watering cacti here for more tips!
Tip: You can actually cut off the top of a cactus and repot that if the base is rotting. Just be sure to cut above the rot.
Cactus Black Spots From Pests
If your cactus has small black spots, it’s likely that it’s suffering from an infestation of pests. The most common pests that attack cacti are aphids, mealyworms, scale, and moths. Small black spots are more likely from scale, as that’s what scale looks like.
Caring For a Cactus With Pests
If you think your cactus has pests, the first step is to isolate the plant from any others. This will help prevent the pests from spreading to your other plants.
Next, use a cotton swab or Q-tip dipped in rubbing alcohol and gently apply it to the affected areas. This will kill the pests without harming your cactus.
You can also use a pesticide made specifically for cacti, which you can find at your local nursery or gardening store. Follow the instructions on the package for best results.
Prevent in the future: The best way to prevent pests is to keep your cactus in a dry, well ventilated spot. Overwatering your cactus can also encourage pests to come to your plant, so only water the soil when it’s dry.
You can’t always prevent pests, so try to keep your cactus healthy so it can withstand an attack of bugs if they come back in the future.
Cactus Turning Black From Fungus
This is unfortunately one of the most likely causes for your cactus to be turning black, from fungus. There are a few different fungi that can infect your cactus, including crown rot, bacterial necrosis, and phyllosticta pad spot.
Crown rot is a type of fungus that attacks the stem of your cactus, near the ground. It can cause black or brown spots on the stem, which eventually turn into soft, sunken areas. The entire plant can eventually turn black and die if left untreated.
Bacterial necrosis is another type of fungus that can cause your cactus to turn black. This one usually attacks the roots of your plant, causing them to rot and die. The plant will eventually wilt and turn black as a result.
Phyllosticta Pad Spot
Phyllosticta pad spot is a type of fungus that causes small, dark spots on the pads of your cactus. These spots eventually turn into larger, sunken areas that can cause the plant to rot and die.
Caring For a Cactus With Fungus
If you think your cactus has fungus, it’s important to take action quickly as this problem can spread quickly. The first step is to remove the cactus from its pot and shake off any excess water or soil. Then, allow the plant to dry for a few hours before replanting it in fresh, dry soil.
You can also treat the plant with a fungicide made specifically for cacti. Follow the instructions on the package for best results.
Prevent in Future: The best way to prevent fungus is to keep your cactus in a dry, well ventilated spot. Overwatering your cactus can also encourage fungus to grow, so only water the soil when it’s dry.
You can’t always prevent fungus, but try to keep your cactus healthy so it can withstand an attack if it comes.
Final Thoughts For Why Is My Cactus Turning Black?
No matter the cause, it’s important to take action quickly if your cactus is turning black. The earlier you catch the problem, the easier it will be to fix.