Identifying Black & Dark Brown Spots On Cacti

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If you see brown spots on your cactus and don’t do anything, those spots can turn black later on. That’s why when it comes to this topic, I combine the black and brown spots topic in this one post. This article will discuss the causes where the time you find the spots decides which color they are and the causes where it makes no difference. Stay tuned!

These Causes Will Turn Your Cacti Black If You Find Them Later

As I mentioned earlier, these are the same reasons we discuss black spots on cacti in the article. It’s just that we find the plant when it hasn’t yet turned black. The common reasons are: 

#1. Sunburn

If a cactus accustomed to shade is suddenly exposed to intense sunlight, it can get sunburned. Initially, sunburn might manifest as a pale or whitish discoloration, but it can eventually turn brown. Typically, these spots will be on the side of the cactus facing the sunlight. 

How to deal with brown spots under the sunburn effects? It’s as easy as relocating the cactus to an area under the shade. We should agree that brown spots won’t disappear. This way helps the cactus from getting more brown spots.

#2. Cold or Frost Damage

Cacti like warm and cozy places, so they can have a tough time when it gets too chilly. If they’re out in the cold or frost, they might get brown or black spots, like how we’d get goosebumps in the cold. If they’re left in the cold too long, the insides can freeze up, causing these spots. It’s a bit like getting an ice cream headache, but for a cactus! If you live where it’s cold sometimes, try to keep your cactus inside or wrapped up on frosty nights. If they do get these cold spots, just keep an eye on them and make sure they get back to their warm, happy place.

#3. Physical Damage

If a cactus gets bumped, scratched, or poked, it can end up with brown spots. Just like when we get a bruise from a knock, a cactus can show damage with a change in color. Maybe a ball hit it, an animal brushed past it too hard, or it got scraped while being moved. These brown spots from physical damage are the plant’s way of healing itself, kind of like a scab on our skin. Over time, the spot might fade, or it might stay as a scar. It’s always a good idea to be gentle with cacti and to place them somewhere they won’t get banged up to keep them looking their best.

Other Reasons For Brown Spots On Cacti

#1. Rot

Overwatering or waterlogging can lead to fungal or bacterial infections, causing the cactus tissue to rot. This typically manifests as soft, brown, mushy areas, especially at the base or the side touching the soil.

Read more: Common Cactus Problems (Why & Solutions)

#2. Pest Damage

A common issue with cacti is brown or black spots, often caused by tiny bugs. These little pests bite or feed on the cactus, leaving these marks behind. If you inspect closely, you might spot the bugs or their eggs clinging to the plant. Using a soft brush to wipe them away gently can help. Keeping the affected cactus away from other plants for a while is wise to prevent the pests from spreading. Regularly checking your cacti for such problems will help catch this common issue early and ensure your plants remain in good shape.

#3. Age

As cacti get older, they might get brown or black spots, like how people get age spots as they grow older. These spots are just a normal part of a cactus growing old and don’t usually mean the plant is sick. It’s just like how things wear out over time. But it’s always good to keep an eye on your cactus. If you see a lot of spots appearing fast or if the cactus starts looking unwell, it could be something else. Mostly, though, if a cactus has a few spots as it gets old, it’s just showing its age.

#4. Chemical Burns

Brown or black spots on cacti can sometimes be because strong chemicals have hurt them. This is like a plant version of a skin burn. Maybe some fertilizer was too strong, or something was spilled on them, or they got hit by spray when other plants were being treated. Moving the cactus to a clean spot and avoiding more chemicals is good if this happens. Keep an eye on it and water it usually. The cactus might get better, but the spots might not go away. It’s always best to be careful and not let harsh stuff get on your plants.

#5. Nutrient Deficiency

Sometimes, cacti can get brown or black spots if they’re not getting the right nutrients from the soil. For instance, the older leaves can turn brown if they don’t have enough potassium. Not getting enough magnesium can make them go a reddish color that turns into dark spots. And if they’re really low on nitrogen, their leaves might turn brown. To help them out, add some cactus food to the soil. But before you do, it’s a good idea to check if there’s enough water or if any bugs are causing the problem. So, keep a close eye on your cactus and see how it responds after you care for it.

Final Words

Spotting brown or black marks on your cactus isn’t just a visual change; it’s a clear signal that your plant needs attention. Whether adjusting care routines or taking prompt action to remedy an issue, staying vigilant and responsive is vital. Above all, I hope this guide is helpful to my readers. Let me know what you think in the comment section below! Happy planting!

Succulent City chief editor


Succulent City

Hey everyone! Welcome to Succulent City! We are all about succulents, cacti, and a bit about air plants. Ten years back, in 2013, we began the journey with succulents. It started as a simple hobby, crafting and selling charming succulent-themed pins and decorations. But as time passed, our fascination with these remarkable plants grew, and we gained extensive knowledge about them. Therefore, Succulent City is the blog as you see it is now. Enjoy your visit and happly planting!

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