enter image description hereOur 7ft high cactus has started to develop these brown patches & are definitely spreading. It’s located in a conservatory which is quite sunny but not direct & has been there for a number of years.
I’m sure it’s not water damage but I suppose it’s possible? Nothing has really changed environmentally for it.
We’ll be devastated if it perishes.


2 Answers 2


This is about 4' high, and grown from seed in 1983.

I can't remember a time when it didn't have those brown marks.
Given that they were the only indoor plants I'd ever grown, it didn't occur to me until now that it might be unusual.

I can't guarantee it's the same condition as yours, but for mine it's certainly not been fatal so far.

Potted cacti with marks similar to those in the Question.

Close-up showing details of previous photo.


This is not good. Most certainly because of carbon monoxide concentration being high in your surroundings. How good is your ventilation? Do members in your family tend to sneeze a lot in the morning?

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