At this month’s meeting Costas Papathanasiou gave a talk about his fantastic Ariocarpus collection. I took some notes but I was not quite fast enough to catch everything and probably have some things wrong as well. Please comment with any corrections or extra detail you might have.
There are 6 accepted species in the books; agavoides, bravoanus, fissuratus, kotschoubeyanus, retusus and scaphirostris. Costas thinks that Ariocarpus retusus trigonus should also be a seperate species.
When young they have long tubercles. As they age they get shorter and shorter. With age they lose their tips.
These are the biggest of the Ariocarpus. Prolific flowerer. The more you water, the more they flower. 3 or 4 times per summer.
These are the ‘kings’ of Ariocarpus and a good specimen is sure winner on the show bench. These are flat when they are on their own root and they bulge when they are grafted (because grafted plants can only grow up).
I think the plant on the right is one and I believe it is one of Stuart’s entries in this month’s show.
They are small. About 1 inch to 2 and 1/2 inches and flat with a depressed centre. Very susceptible to mealy bugs which cause skin damage that can lead to rot. Invisible in habit until it flowers. Offsets can form from epidermal cracks
Recommended for beginners. These are Costas’s favourite Ariocarpus. Great variability in appearance. A. retusus furfuraceus has a lot of wool on top, fluff on the tubercle tip and short spine, slightly upturned. A.retusus elongatus have long narrow tubercles.
They have upright tubercles. Very little wool. Can’t see the areole. It can take 15-20 years to get to 4 inches. They start out soft but get hard as nails. They are the most difficult Ariocarpus to grow and they tend to gain a tubercle and lose a tubercle at the same time and thus never get big. The leaf shape is like a boat with a bow and a keel. Rare. I think the plant in the square black pot in the top right of the picture below is one.
Ariocarpus retusus trigonus
Costas considers this a separate species from retusus. It has an upturned curved tubercle and it takes 2-3 years for a new tubercle to extend and the aereol to be exposed in order for it to flower. Due to this, it’s artichoke shaped flowers appear in a ring around the centre and not in the centre. Young plants are susceptible to burning and yellowing of the tips. It is a fast grower.
Watering – Growing Ariocarpus indoors with some light winter watering results in brown fluff rather than the white fluff of Ariocarpus grown in the greenhouse. During the winter you can preserve the fibrous root extensions by lightly watering around the outside edge of the pot. Give Ariocarpus plenty of water and plenty of food. In habitat Ariocarpus are fed nutrients by the mountain rains and flooding. Start with a light watering in April to wake them up. Water once the temp. hits 21C. Water at night to avoid marking due to water lensing. Water around the outside or from the bottom to get long roots. The hotter it gets the faster they grow. If you have aborting flowers you are probably not giving it enough food & water. The flowers should just shoot up fast. Plants mostly flower from the center from the new tubercules. Costas recommends a thin dilution of Chempack and uses sand filtered rainwater for his plants.
Pots – Grow Ariocarpus in clay Tall Toms (also called Long Toms) to allow the plant to hang – have no more than 2 inches clearance to the edge of the pot otherwise you are risking root rot by having too much extra potting mix for moisture to hide in. Ariocarpus have a long tap root that in habitat can even crack stone. Habit harvesting typically involves cutting the root and re-rooting the plant which can take 4 or 5 years and the roots form from the outside of the cut centre root. Costas has his plants sitting in a saucer and uses a moisture sensor during cloudy periods to make sure he doesn’t overwater.
Potting Mix– 1/2 John Innes and 1/2 grit plus limestone chipping and fine Cornish grit. Don’t use too much Cornish grit because it retains a lot of water. Change soil every 2 years. Change the surface grit covering every couple of years to remove lime and salt buildup.
Grafted Plants– Grafted plants can be recognized by their bulging growth. Grafted plants grow faster and have shorter lifespans (10 to 15 years maximum compared to regular plants that can survive for more than 100 years). They also often have brown markings from scorching because their fast growth results in thinner skin.
Misc. Tips and Tricks– You can force flowering by simulating shorter days by watering the plants heavily and then moving them inside for 2 or 3 days. “Dutch Acceleration”
To see Costas’s plants if you missed this talk be sure and go to the National Show next year.
Some Other Ariocarpus Resources
ARIOCARPUS: LIVING ROCKS OF MEXICO
CactiGuide Notes for the Genus: Ariocarpus