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[Roze]

Dear cacti lovers:

I just have the lucky to add some little Obregonia denegrii to my collection.

 It happens I never grow anything like this before, there some of our cacti masters that can share some advice on the type of soil , watering and light to make this fellas happy?

Any help will very appreciated.

Thanks!

" The term “living rock cactus” refers to several Mexican genera of dwarf, cryptophyte cacti plants, and particularly to cacti belonging to the genus Ariocarpus (especially A. fissuratus).

The “living rock” are low-growing plants that live almost buried in the ground and often have a rosette of tubercles that are flattened and resemble (for colour and texture) the surrounding soil surface. Most of this plants almost entirely lack spines but are covered by warty tubercles and woolly hairs, so they often mimicry the stones among they grow (hence the name living stones). Water is stored against the dry season in the thickened tap-root or in the underground plant body reservoirs. Often these plants melt so efficaciously with the background that are completely invisible if not flowered.

Other cacti that are usually called living rock comprises:
Astrophytum, Aztekium, Epithelantha, Geohintonia, Lophophora, Obregonia, Turbinicarpus and Strombocactus"

[happyconcacti]

I'm definitely not the person to answer this, but from what I've seen people use a lot of pumice for the rock lovers.

1 Like Roze likes this.

[Urban Elements]

Dear cacti lovers:

I just have the lucky to add some little Obregonia denegrii to my collection.

 It happens I never grow anything like this before, there some of our cacti masters that can share some advice on the type of soil , watering and light to make this fellas happy?

Any help will very appreciated.

Thanks!

" The term “living rock cactus” refers to several Mexican genera of dwarf, cryptophyte cacti plants, and particularly to cacti belonging to the genus Ariocarpus (especially A. fissuratus).

The “living rock” are low-growing plants that live almost buried in the ground and often have a rosette of tubercles that are flattened and resemble (for colour and texture) the surrounding soil surface. Most of this plants almost entirely lack spines but are covered by warty tubercles and woolly hairs, so they often mimicry the stones among they grow (hence the name living stones). Water is stored against the dry season in the thickened tap-root or in the underground plant body reservoirs. Often these plants melt so efficaciously with the background that are completely invisible if not flowered.

Other cacti that are usually called living rock comprises:
Astrophytum, Aztekium, Epithelantha, Geohintonia, Lophophora, Obregonia, Turbinicarpus and Strombocactus"

I have a few aztekium, lophophora, and also a few obregonia, and in my experience the obregonia like to be in the shade and for me does best in a coir, growstone, crushed rock mix with little sips of water. I watered 1 of my obregonia like a trichocereus in black gold cactus soil and it died off fast.

I have been growing them for a few years and that's all I have really figured out.  Treat is just like a lophophora and it will love you long time!

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[Roze]

I´ve read that the difficulty on growing this type of cacti is watering . They are very sensitive to rot. Best is to water from beneath to prevent any remaining water between the scales. Maintain a minimum temperature of 10 °C in winter and do not water while the plant is in rest.

About the soil I used a good draining mix : 4 parts of river sand, 1 part of soil and 1 parte of vermiculite. Hopefully with this mix water can drain quickly stopping rot occurring.

Few more tips:

If growing it in a greenhouse, don't put it in full sun. It's one that prefers some shade. If on a windowsill, it's unlikely to get too much sun.

Dry in winter, or the taproot will rot, but if the soil is well drained  water well in summer. If not given enough water, the tips of the tubercles will dry out.

Wish me luck! 

Ps:

O. Denegrii is native to Tamaulipas, Mexico where it is now endangered due to a variety of factors including habitat loss, collection for medical, scientific and collective purposes and uprooting by livestock. It is said to have antibiotic activity and was one of several cacti species to be considered a false peyote by the Tarahumara people of Mexico. This solitary, low-laying cactus, which typically stays under six inches, is often shadowed by shrubbery. For that reason, it prefers light shade. For brief periods, it can survive temps as low as 20 degrees Fahrenheit. Being a slow-growing ornamental, it is a great candidate for grafting onto faster-growing root stock such as San Pedro, blue myrtle or pereskiopsis.

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[LSoares]

You're on the right track, although I'm not sure what you mean by "soil". The "living rocks" were once considered very difficult until people switched to purely mineral mixes; apparently, organic matter is offensive to their roots. The basis of my mix is appropriately crushed lava rock, mixed with several other things (I don't like pumice or perlite, as they tend to float to the surface of the pots after a while). For most mexican miniatures a handful of crushed limestone is considered benefitial. Watering from below is fine if you remember to flush frequently with clean water, otherwise salt buildup will quickly become a problem. I prefer to water from above when a few days of sun are forecast (not unusual here in Portugal) so the plants have time to dry out. I also use a top layer of large(ish) pebbles (0.5-1cm) as a means of protecting the sensitive neck of these plants (but the use of top dressing is controversial).

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[misplant]

what works for one person may or may not work for the next, but the underlaying theme everyone has mentioned is water control. 

All of my living rocks get front row seating in the gh, as close to the UV filtered, Suntuff polycarbonate panels as they can be.  I may water my Obregonia 2-3x yearly, and its in a mix containing small amounts of composted forest products. 

Most of my cacti are 'hard grown', meaning they get very little water, infrequently.  Living rock cacti seem to do best in pots that are only slightly larger than the plant itself and older lophs & ario's with larger tap roots need deeper pots.

[spaceman101]

Hey LSoares . Why don't you post up some of your beautiful Ariocarpus, Turbinicarpus etc.?

[spaceman101]

Hey Misplant is that you Zeph?

[sporehead]

I don't know from any experience, but I've also read that these cacti prefer mineral or rock only as a substrate. Theres a great paper on it. stone eaters pdf