Cactus rot is a very common problem, and one of the main causes of their death. It can start anywhere on the plant – from the bottom, the top, or somewhere in between.
But just because your cactus is rotting doesn’t mean you can’t save it. No matter where it starts, there are steps you can take to remove it and stop it from spreading.
In this post, I’ll talk about the causes and symptoms, answer all of your questions, and give you step-by-step instructions for how to save your cactus from dying.
Why Is My Cactus Turning Brown?
When a cactus turns brown and gets soft, mushy, or squishy, it’s likely caused by rot. It’s not always brown, it can also appear black or yellow in color.
Unfortunately, once it starts, it won’t stop. Without intervention, it will continue to spread all the way through the entire stem, eventually killing the plant.
Related Post: How To Care For Cactus Plants
Why Is My Cactus Rotting?
The main cause is usually excess moisture, which can either be from overwatering or from water pooling and sitting on top of the plant. But sometimes it could be caused by a fungus or disease.
- Cactus bottom rot is usually caused by overwatering. An overwatered cactus doesn’t always start rotting right away, and it can begin below the soil surface. So it might not be obvious that was the cause.
- Cactus tip or stem rot is common on damaged plants. It is usually caused by a fungus or a disease infecting the wound, or from watering getting into it, causing the plant to rot from the inside out.
How To Save A Rotting Cactus
Once you notice rot you’ll need to act fast, because it will spread quickly and eventually kill your cactus. The steps for saving your plant depend on where it started.
So first I will show you the steps for how to save a cactus that is rotting top down. Then, in the section below that, I’ll talk about saving one that’s rotting from the bottom up.
Related Post: How To Water A CactusPlant
How To Save A Cactus Rotting Top Down
Cactus tip or stem rot can be very deceiving. You may notice small brown spots and think that there’s just a tiny bit.
Then, once you start removing the bad spots, many times you’ll realize that it’s much, much worse on the inside than it looked on the outside.
So first, take a moment to prepare yourself for what you may find once you start cutting. Ready? Ok, let’s do this one step at a time…
Step 1: Choose the right tool – You can use either a sharp knife or a pair of pruning shears to remove the rot. If your cactus is really thick, then I recommend using a sharp knife.
For small plants with thin stems, precision pruners or bonsai shears would work great. Just make sure they’re super sharp so they don’t crush the stem.
Step 2: Clean the blades (do NOT skip this step!) – Whatever tool you choose to use, it’s extremely important that you clean and sterilize it before making any cuts. This will help prevent infection or the spread of disease and fungus spores.
You can simply wash the blades with soap and warm water, or sterilize them with rubbing alcohol, and then dry them before you start. I also recommend that you clean them again between each cut.
Step 3: Remove the rot in layers – It’s best to cut the rot off in layers so you’re sure that you got it all, without removing too much of the healthy tissue in the process.
In the photo below, you can see that the center of the healthy-looking portion of my cactus still has rot on the inside. So we have to keep going…
Step 4: Continue removing layers – As you work your way down, slowly cutting off small sections of the stem, the rot will get noticeably thinner and thinner.
But remember, even a tiny bit of it will likely continue to spread. So, be sure you remove all of the brown, soft, and mushy cactus material until no more signs of rot remain.
If yours is outdoors, make the last cut at a downward angle so water won’t settle into the wound (which will likely cause it to rot again). I would also move it to a dry area where it’s protected from rain until the wound has callused over, if possible.
Unfortunately, the rot on this cactus was really severe before I noticed that the top was turning brown. So I had to cut off over half of the stem to get rid of all of it.
As difficult as it was for me to remove such a large section, I know my plant would have been dead in a matter of weeks if I hadn’t done anything to save it.
Monitor Your Plant Afterward
If you have to perform this type of surgery on one of your beloved cacti, keep an eye on it afterward to make sure it doesn’t continue to rot. If it starts again, follow the same steps above to remove the new rotting section.
After a couple of days, the wound should callus over, and your plant will eventually send out new growth near the cut.
I was very sad that I had to basically cut my cactus in half to remove all of the rot. But heck, in the end I think it added more character to the plant, don’t you?
How To Save A Cactus Rotting Bottom Up
Unfortunately, if the bottom of the stem or the roots are rotten, then the only way to save your cactus is to try propagating a healthy cutting.
Take your cutting just above the rotting section. Then follow the steps above to remove additional layers as necessary to get rid of all of it.
Allow the cutting to dry for several days until the end has callused over. Then dip it in rooting hormone and stick it into a sandy soil mix.
Don’t water it until you see new growth on the cutting. Depending on the variety you have, it can take several weeks for roots to develop.
Related Post: How To Make Your Own Cactus Soil Mix (With Recipe)
If you want to learn all there is to know about maintaining healthy indoor plants, then you need my Houseplant Care eBook. It will show you everything you need to know about how to keep every plant in your home thriving. Download your copy now!
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Share your tips for saving a rotting cactus in the comments section below.
Vicky says
Hi , I’ve just read your article in hopes of saving two cactus, a rather sad story. … my sweet precious daughter in law recently lost her father who she did not really know except by phone and she inherited his two beautiful cactus … they are huge to me .. at least 5 feet in pots … since we had to move them immediately , I lived the shortest distance ( she lives an hour away )we brought them to my house .he was a heavy smoker so they spent about 5 days under my porch outside due to the cigarette odor… we moved them inside and noticed it turning yellow .. now I am going to follow your instructions because we have some tip rot … but the pots still smell terrible.. will it shock them too much to repot them and cut them also ?
Thank you so much for making instructions easy to follow!
Amy Andrychowicz says
So sorry to hear that your cactus plants are turning yellow and have tip rot. I do not recommend repotting them at this point. It’s best to wait until they recover from cutting off the rotting parts before you repot them. If it’s warm enough outside, I would just leave them out there for the summer. Keep them in a shady spot so they don’t get sunburn, and slowly move them into the sun. Just make sure the pots have drainage holes, or they will drown when it rains.
Dusk Pendragon says
Thank you so much for all this info. My family has a small cactus that i believe is just over 30 years old and he’s very important to me for some reason. He’s just always been around. Anyway i don’t know a lot about cactus care, but recently he snapped in two revealing some pretty extensive internal rotting and its worrying me a lot. He’s only a small cactus and we have already cut a large portion of him away but he still has brown mush inside. His skin is still sturdy and a healthy green and his spines are firmly attached, as well as being sturdily rooted in the ground. I don’t know how deep the rot goes and worries me so much. Is it possible to scoop the rot out and he would recover or should I just keep cutting and hope there’s some without rot before I it his roots…
Amy Andrychowicz says
Oh no, so sorry to hear that your cactus is rotting on the inside, that is so frustrating! If I were you, I would try doing exactly what you said. Scoop out all of the rot, and keep your fingers crossed that it will survive. Good luck!
Kellie says
I have an optunia species that had three large paddles from the original paddle. Two of the top paddles were affected by the recent freeze we had and looked like they were rotting at the tops of each paddle. I used a clean knife to remove each paddle from the original paddle, making sure to clean before cutting a new paddle. I then Removed the top half (to include the rotting area) from each removed paddle. I now have my original paddle with a single secondary paddle and then my two removed paddles with the top halves removed. From your experience, is it possible I could save these half paddles and new growth occur? It’s similar to this article but with paddles
Amy Andrychowicz says
Yes, I would definitely try rooting the cactus pads that you cut in half. They are very prolific, and should regrow no problem. It’s certainly worth a try. 🙂
Don Echelberger says
what are the white things attached to the spines of my cactus? does not appear to be mealy bugs or scale. they are only on the spines. I don’t see any ants, so I don’t see how they get there.
Amy Andrychowicz says
Some types of cactus plants are naturally hairy, and some have more on them than others. As long as you’re sure they aren’t bugs, then it’s probably normal for the variety you have.
Margie Holmes says
I have been given a barrel cactus and its black at the bottom to about a quarter of the way up and then brown for another quarter. What can I do to save it. We get a lot of rain here on the coast of NSW Australia. Tks Margaret
Amy Andrychowicz says
Sorry to hear that your barrel cactus is rotting from the bottom up. Unfortunately, I don’t think you can take cuttings of the healthy tissue to propagate. Look for any healthy pups around the base, or any growing out of the top or side of the mother plant that you can separate and pot up. Otherwise, you could certainly could cut the top off and try rooting it as an experiment. But, as I said, I don’t think it will work with a barrel cactus. In the future, make sure it’s in a very fast draining sandy soil, and try putting it in a spot that doesn’t get much rain, or where the soil can stay dry. Good luck!
AZ Desertgirl says
My ten foot tall Pilosocereus has a black flesh fungus. I have followed your helpful instructions pretty much to a t. I’m very concerned because it has three large arms that are supported by this trunk. The stalk appears to be very steady and stable. I removed the needle spikes first, so I could get closer to the base. Black, gooey liquid started to emerge. I thought I was going to be sick!
I live in Phoenix, and we have had horrible extreme heat with drought. I thought I was doing my columnar grouping a favor by watering it a gallon, every other day. But then the monsoons showed up! 3 inches of rain doused my grouping. UGH!
Anyway, I performed surgery on my guy. I removed a lot of very wet, black fresh. I let it dry out for two days, but I need to go back and finish it. The rest is in a harder to reach area. I’m hoping he doesn’t crash down on me. 😉 I need to finish the job, but thinking ahead to how to apply the Sulphur powder.
How would you suggest that I apply the Sulphur powder to the base? I think this is stumping me. I believe natural sunlight will help kill the fungus. Do you believe that to be true?
Thank you for much for your knowledgeable step by step instructions! You are a lifesaver. I’m hoping my surgery to this 10 foot tall cactus can indeed save him.
Please reply on the best way to apply Sulphur powder. Thank you!!
Amy Andrychowicz says
Oh no, I’m so sorry to hear your huge cactus plant has started to rot, that is such a bummer! I’m thrilled to hear that you have been able to follow my instructions and get some healthy cuttings from it, that’s fantastic! Honestly, I have never used sulphur powder before, so I can’t speak from experience. But I do know that there are powder duster tools that you can buy just for this purpose. Check your local home improvement store, garden center, or search online to see if you can pick one up. I think that will make the job much easier for you.
IAN LIM says
Hi, my cactus has been getting dry and brown in patches at the bottom. I’m not sure how to save it 🙁 Do you have any tips?
Amy Andrychowicz says
Check to see if the brown patches on your cactus are soft or mushy. If they are, then it’s rotting, and the only way to save it is to follow the instructions above to take cuttings. Otherwise, if the spots are dry and the cactus has new growth, then it may recover. Just be sure to water very, very sparingly. Let the soil get completely dry, and then give it a tiny bit of water. The soil should never be wet. Good luck!
IAN LIM says
Thank you! 🙂 The brown patches are dry, so I’m watering it when the soil is almost sandy and dry.
Amy Andrychowicz says
You’re welcome!
Bryon Gibson says
My moon cactus has a black spot on the side of the round top (my cactus has a pink round top & a green bottom it splits 3 ways naturally) and the bottom is so weak that my cactus has fallen over… I’m afraid to ask but I’m going to any way… Is it to late to save my cactus ?!
Amy Andrychowicz says
Oh boy, if the whole thing has fallen over and your moon cactus is soft and rotted, then I’m afraid it may be too late. 🙁
Maggie says
Hi! I’ve had an old man cactus plant (also known as bunny cactus) that has turned brown on the bottom. I think my family is over watering it. I don’t know how long it’s been like this. It’s only a couple inches long, and it’s in a pot. I am scared to cut the good part off because it might get all dry. Please give me some tips, I really don’t want my favorite cactus to die.
Amy Andrychowicz says
Bummer to hear that the bottom of your old man cactus is rotting. How much of it is brown? If it’s only the very bottom near the soil line, and it’s firm and not mushy, then that’s pretty common. Just monitor it and make sure the soil stays dry from here on out. However, if it’s a larger part of the stem and it’s mushy, then the only hope you have to save it is to try propagating the healthy top part of the stem. If there are any offsets on the top, then those would be easier to root than a cutting of the main stem. Either way, it’s worth a shot to try to save it, because if it’s rotting at the base, the whole cactus will die eventually. 🙁 Good luck!
Sallie says
Hi Amy, we have a huge euphorbia not sure which one it is. This plant is outdoors and at least 40 years old. Last year most of the cactus had turned slightly yellow. Now over the months several branches are turning brown and dried up. We have been cutting off most of the dried up branches to try to save the cactus, but it doesn’t seem to be improving. Do you think this is rot? The cactus isn’t mushy or wet like most people report.
Do we need to be more aggressive with cutting all dead off of it? Is this cactus doomed?
Amy Andrychowicz says
It sounds to me like your cactus may have experienced a minor case of rot at the base or root rot back when it turned yellow, and now the rest of it is slowly dying. My guess is that the center of the main stem has rotted away, and may even be hallow inside. If I were you, I would try to take cuttings of healthy green growth, and root them just in case. Then continue to prune off the dried up branches as you’ve been doing, and hope for the best. Good luck!
Don't know what I'm doing says
Hi,I have been caring for my sister n laws plants and she has a couple of different cactus and I noticed that her Mexican cactus was turning a little lighter green when I looked at it it was mushy and look like water coming out of it after looking on line I decided to cut the new shoots off to save them But not sure how long to let them heal over and if I need to get the root hormone to get them to root….Help!…
Amy Andrychowicz says
Oh no, sorry to hear that your cactus is rotting! You did the right thing by taking healthy cuttings before the entire plant died, good job. I would let them callus over for at least a week. Once the wound is crusty and firm, double check them to make sure there’s no sign of rot anywhere on the cuttings. if they look healthy, then you can propagate them. Yes, I recommend getting the rooting hormone for sure. That gives them a much better chance of rooting, and is worth the few extra dollars. Just make sure to use a very porous soil mix for them, and not regular potting soil. Here’s more info on that… How To Make Your Own Succulent Soil (With Recipe!)
Efren says
So I have this globe cacti, partially yellow on the yellow not that squishy, and the usual white cloudy spikes are now gone. I’ve been looking everywhere from apps to step by step procedure so first I replanted with available sand and soil at my house, a few days later there’s this hole and some crawlies I realized this was a mealybug and is left with distribution propagation
Amy Andrychowicz says
Ugh, sorry to hear you found mealybugs on your cactus. Here’s how to get rid of them… How To Get Rid Of Mealybugs On Plants, For Good!.
Marion knox says
I have a very large barrell cactus that has rotted fromthe bottom. I have cut of 1/3 from the bottom . The cactus was full of water ,what canido now is it savable?
Amy Andrychowicz says
Oh no, sorry to hear your barrel cactus started rotting! Unfortunately, once the base rots like that, then you may not be able to save it. If the are any offshoots or babies around the base, then you can remove those and pot them up. You certainly could try to root the healthy top piece that you cut off. But if it’s full of water like you mentioned, then it will likely just continue to rot. 🙁
Hannah says
Hi I have a small cactus which my friend brought for me the bottom has gone black (so I’m guessing it is rotting) but the top of the plant rather than looking waxy has gone almost leathery in the way it looks and feels quite hard. Do you think I will still be able to save it!
Amy Andrychowicz says
It sounds to me like your cactus plant might already be dead (sorry!). But, it’s hard to know for sure. I would try cutting off the rot in layers like I describe in the article to see if there’s a healthy green stem. If you find green, then you can try rooting it. Good luck!
Trudi says
I have a+50 year old cactus that has lost its outer skin near the bottom. It’s dark and dried up so I removed it and the bare inner core of the cactus is showing. It looks like wood bark. The rest of the cactus is healthy, sprouting babies on top.
Is this rot? What should I do?
Thank you
Amy Andrychowicz says
If the base of the stem is completely hollow and dried out, then it sounds like your cactus was rotting at one point, and now it’s dried up. Follow the instructions in the section above titled “How To Save A Cactus Rotting Bottom Up” for details on what to do.
Lea says
To me this sounds more like corking? I noticed he same on my cactus, so I googled a bit and the term corking came up. As I´ve understood that´s just the normal aging prosess of a cacatus and I don´t think it needs to be removed. It just happens becuse the plant needs more support. Corking makes the base of the cactus hard, dry and dark, not squishy.
Mollie says
Hi! I have a cactus that is definitely rotting! The bottom is black and spots throughout it are black and yellow. I was going to throw it out but I noticed that the new growth that had started when the cactus was healthy, has started to grow more! It’s such a tiny piece, maybe an inch tall that has grown but I’d love to save it. But I don’t know how or if it’s possible since there seems to be rot throughout the entire plant!
Amy Andrychowicz says
Oh no, sorry to hear your cactus has rotted! I would try cutting off the small green part to see if you can propagate it. But, since it’s such a tiny piece, you may not be successful.