A step-by-step guide on potting cacti on mineral soils, P.2

In our previous installment, we discussed my approach on potting cacti, which relies heavily on the application of ecological contexts. In the second part of the series, a question is raised: how do we apply ecological data when we do not know the name of the cactus at hand? As you probably very well know, one cannot make any attempt at research unless he knows what he has. Fortunately, there is one very simple answer: all xerophytic cacti need mineral soils. Even those that are known to occur within the vicinity of organic soils still have their roots firmly embedded on underlying rock.

What we have here is a recently purchased plant whose name still escapes me (as I readily acknowledged from a previous post, my cactus identification skills still leave much to be desired). However, notice the rather intensive covering of spines. In many species of cacti, such armory as well as the presence of a pruinose layer are interpreted as adaptations to the extreme conditions that highly arid environments present. Good examples of the former include Echinopsis leucantha and Escobaria tuberculosa. Glaucous covering on the other hand, is exemplified by species such as Acanthocalycium glaucum and Copiapoa cinerea, and this feature is even reflected in their species epithets, with the Latin-derived cinerea translating to 'gray'- an allusion to the waxy coating.

Note the poor root development of this example. Like most locally produced succulents, this one was subjected to growing on leaf litter.

As with our example from the previous post, we will be using a rather tall pot, photographed here with crocks. Since this plant will be subjected to extreme conditions, a taller or larger pot will allow more stable conditions and thus a greater margin of error. The white paint should reflect much sunlight and avoid overheating- a very real possibility had I opted to use a darker colored container.

The bulk of the potting medium is composed of S1 and ungraded pumice stones. I forewent the use of pumice sand, or any sand for that matter, as we would want a very fast-draining and fast-drying medium which echoes the typical substrates found on very arid and very rocky habitats.

Below are larger rocks that I chose for this set-up, selected for their paler coloration which will serve the same purpose as outlined on my reasoning for choosing the pot presented above. In addition to these minerals, I also took the liberty to once again employ some sedimentary clay as a finishing and unifying touch.

Potting the plant is pretty straightforward, and followed the same procedure as the Melocactus from the previous installment. The spines recall the sedimentary clay's coloration.

After some heavy spraying, here is the plant in its new pot, positioned to its new address on the rooftop garden. The warmth of the afternoon sun lends a glow on the overzealous bristling barbs that seem to rabidly protect the green body within. In the coming days, months, and perhaps even years, such formidable spination will be put to the test beneath some of the most intense tropical sun a plant can possibly be presented with. It should, and it will.

Note: I reckon this to be Lobivia schieliana. Will have to wait for the flower to be certain.