I have noticed my cactus having this strange rip since a few weeks.
Can anyone tell me what the cause is? I have put it in a room where there is a temp of about 14 degrees Celsius for the winter. I give it a very small amount of water once a month.

At first your problem looks white indicating sunburn or scale even, but then a closer look shows a browner color faintly coming into play outlining the white. Is it starting to feel softer in those parts? If so, it's root rot. Which is not good at all. Typically you can cut away the cactus tip if it's rotted or something like that and save the rest of the cactus but it could be too late for yours if it's starting to feel soft all over.

It's hard to say from the pictures without being able to feel the actual cactus.

I usually reference this site when I have cactus issues or need help identifying issues.

http://www.cactiguide.com/cactipests/

Hope this helps and good luck!!

What kind of soil is it in?

I felt the cactus all over and it doesn't really feel any softer at the moment. I also read on the link you sent (thanks for that by the way ) that sunburn in the second stage does get a brown coloring. I'm guessing as it isn't soft it is sunburn.

The soil is still the same soil as when I got the cactus, so I'm not sure what is in it. I didn't get to re-potting it yet.

Thanks for the advice, I'll have to keep an eye out for too much sun.

It almost just looks like normal scaring/sunburn to me. And it's not actually ripped. It's just a scar in the rib from what I can see. Which is no issue at all unless you want a perfectly green plant.

Could it be scale? Can you rub any of it off?

Sunburn would more likely occur on the outer extremities of the plant, not inside the crevices like that. I would guess it's a soil issue. Often cacti grown in greenhouse situations will be in soil that is not good for non greenhouse situations. I'd repot it into a good cactus mix, or a regular potting soil mixed 50/50 with pumice

Will do this as soon as I can. Was planning to put it in a bigger pot anyway.
Two questions:

- Would perlite also do instead of pumice?

- Re-potting in this time of the year is ok? Winter here.

Ez, I haven't tried rubbing it off, will try that as soon as I get home.

Thanks for all your advice guys.

I tried rubbing it off, but I couldn't get anything off, so I think it's either sunburn or a soil problem like Nicechrisman stated. To be sure I'll re-pot it as soon as I find the time.

Perlite does work just like pumice, but pumice is WAY better. Hehe. Pumice ftw. And I've heard people say re-potting in winter is the best since it wont interfere with the growth cycle, it'll have time to root in the new soil. But I've also heard people say that re-potting in spring is the best time since the plant is starting to actively grow.

Is the plant dormant right now or is it growing?

I wasn't sure when to re-pot, but I guess your advice makes it easier to decide. Either winter or spring
At the moment it is dormant, not growing at all. It is in a room where the temp is between 10 and 15 Celsius. I do give it very little water when I see that the soil is bone dry (once every 3-4 weeks).

I'll see if I can find some pumice instead at my local plant store.

I don't think it has anything to do with watering but you actually don't have to water the tricho's at all when they are dormant. That's your best way of knowing for sure you won't get rot.


I had a Tricho put at the attic in a previous house and forget about it for 1,5 year or so. It didn't get water for that period and survived without problems.

I think it's just a scar from whatever reason. I have several trichos which have similar spots which appeared for no reason and they are doing fine.

I agree with pokeus. I think it's just a scar. If it isn't mushy the i wouldn't worry.

And just as many people (including me) say repotting is best when the plant is in full growth - then the roots can rapidly re-establish themselves in the fresh soil. Anyway, that is when I repot mine.