I have reason to beleive its O.azurea.

But is your plant "grown in its natural environment"? Besides, in nature, only a small fraction of the seeds germinate, and even a smaller fraction reaches maturity. On top of that, some natural seedlings often dont grow in ideal conditions even in their natural habitats( lack of nutrients...

Citric acid crystals? There is a thing called "limontus " here. Its citric acid used in preservation of food.Its some kind of powder like baking soda or vanilla.

Cylindropuntia whipplei fa. Fredonia (dw) (Seeds) Arrojadoa dinae HU 399 (Seeds) Arrojadoa marylanae (Seeds) Ferocactus latispinus v. flavispinus (Seeds) Opuntia phaeacantha v. gigantea (n.n.) (dw) (Seeds) Opuntia aciculata Hybr. nat. (dw) (Seeds) Oreocereus trollii Thelocactus hexaedrophorus v. llo...

Well, to be blunt, cactus growth is non-linear. For example, my cereus(whatever it is) when propagated 4 years ago, had to cut off the tip(rot). The first offshoot it produced it took 2,5 years to be 15 cm long. Then it broke. It produced a second one, now over 30, wider and sturdier, in just this s...

This long spined opuntia i find very pleasant to look at(for a plant that looks like a torture device anyway)
I have my theories, but if anything else, im sure its not an engelmanii variant, the spines are too short, and not tip dense enough. Id if you can, please.

So, ive got two similar, yet diffrent ferocacti,of which i beleive is an emoryii, and the other hystrix.

Can i guess that your plant had ridges at some point? Because of what i could tell, it somehow lost them over time.
And im going to assume its the same plant - https://cactiguide.com/forum/viewtopic.php?t=33238

Ive looked it up. Seems that variant has "identity issues" and has diverse traits. The site is japanese, so if you figure out what it says, congrats http://tytsks.blog39.fc2.com/blog-entry-186.html llifle states that they are all subtypes of gymno. mihanovichii friedrichii http://www.llifl...

"water is too alkaline. " yes it is. But the rainwater is also contaminated( we managed to surpass new delhi in PM 10 concentrations).
So, basically, ive got to acidify my water. Will alcoholic vinegar do the trick? Suppose ill have to mix it in the range of 5,6 to 6....

It comes down to skill. Will try to order from uhlig, but a lot of their stuff are out of stock.

Yep. Dont bother it for a long while. Water normally after a while.

Thats actually great! How.... good are their seeds? Selection is great though.

I think its dead. Should possess turgor and green buds even when dormant.
The fact that the branches wrinkled like they did means its been out of water for too long.

The sole reason would be that " the original" hylocereus root stocks have horrible roots, offshoot easily, and dont last( though i did start a hylocereus plant from them). To combine that with my inability to graft properly,difficulty raising south american plants, lack of available rootst...