It sounds like you are expecting this to be an exact science, purely related to minimum temperature. Average temps, duration and frequency of cold temps, hydration, humidity, and nutrition may have part too, getting early morning sun (or not) and local warming on the tips may make a difference. The...

Shane wrote: ↑Thu Dec 05, 2019 9:11 pm I found one of my plants has something similar.

have mercy ... NOW i'm beginning to wonder if what's going on with my cactus is not something that's "normal" ...

I like the big spines btw. OK Elie ... I've made the post in "Cacti Identification" about the three "Pilosocereus pachycladus" . Go lookit the spines on the taller one. It ... Ahhh Hahhhh! It JUST occurred to me that THAT is ANOTHER difference between them ... some of the spines...

I have three cacti that have all been identified as Pilosocereus pachycladus . And this is the problem. Because I think that one of them is different enough from the other two so as to call its ID into question. 1) Original Height. I bought these three cacti over a 2 year period, and at one time, th...

I've got a post going on in "Sick Cacti" where the result MAY be (but NOT positively) that what is going on with that particular cactus is cold damage. My greenhouse, as primitive as it is, has a thermostatically controlled electrical outlet that I have a small 1500W fan-powered heater plu...

I like the big spines btw. Ha, ha! You like them spines dontcha? Wait till you see the spines on the other one ... the one that will cause me to bring these two cacti BACK to the Cactus Identification section. Keep an eye open in that section over the next day or so and let me know what you think. ...

It's very weird, and I wish I had a better answer Me too! ------------------------------ Oh also did you apply and fertilizers, pesticides, etc recently? That could have an effect nah ... I normally fertilize every time i water, but this hasn't even gotten water in maybe a month. and besides ... I'...

TimN wrote: ↑Mon Dec 02, 2019 7:32 pm Very odd! I've only seen damage on the ridge of the ribs on plants exposed to cold, and it didn't look like what's pictured here.

Tim

I got the topic for the Trichocereus grandiflorus posted in this same "sick cactus" area ... it looks a lot the same. Go take a look at that please.

Take it with a generous pinch of salt for sure, but it indicates a very warm locality. So it sounds like you are telling me that the minimum temperature requirements for this cactus are higher than the 45F that I have my thermostat set for ... but then WHY wouldn't I have gotten cold damage on any ...

I've been going through a different topic regarding two specimens of Pilosocereus pachycladus and I'm pretty sure that we've all decided that it was cold damage ... DESPITE the fact that I've got a thermostat in the greenhouse that doesn't let the temperature fall below 45F. This cactus was severely...

I have no experience in cold damage so i can't tell about that. Well, thanks for thinking enough of wanting to help enough to make a reply. These come from warm parts of Brazil. I just checked one habitat location, temperatures are very rarely below 50deg F there. I think you have cold damage. You ...

I see a LOT of discussion, but very little evidence one way or another for soil mixtures that contain a high percentage of inorganic material. NOTHING wrong with that, and I do not in any fashion mean to be disrespectful of anyONE or any comments or discussion ... but nothing works like good evidenc...

I have a question: what if i used a 100% mineral mix and then put a layer of rich organic matter on top so that the nutrients leach down. Since it is at the surface, it will dry very fast and the roots will only be in the mineral mix which dries fast too NO layering, NO layering. NO layering. I urg...

The expiration date on this stuff was only a couple years after I bought it, but maybe they're being conservative. Hi Spence ... I JUST found this mycorrhizae post in Nov 2019 They're in the business of selling this stuff to you, so they're going to give you a conservative expiration date in order ...

The last word on over/under potting has yet to be said. While what davidyjones and 7george says is true, it is not the whole story. The faster-growing cacti will have to be re-potted less often if planted in a larger pot, but there ARE cacti that not only like being underpotted, but actually thrive ...