Living Rocks of Mexico
Growing Ariocarpus From Seed
  home [ Literature ][ Cultivation ]  


This article is reproduced form The Cactus and Succulent Journal (U.S.), Vol. 71 (1999). No .4, p210-215 with the  kind permission of the Editor and Andreas Laras.


All photos by the author

"Art is the imitation of nature" said Aristotle. Although in the realm of fine arts I am better represented by the famous Bertolt Brecht quotation, "Art is not a mirror held up to reality, but a hammer with which to shape it", the words of Aristotle perfectly capture the essence of our horticultural art. In practicing horticulture we learn from and mimic nature in order to produce plants that imitate nature on their own accord and stand by themselves as objects of art.

My first encounter with a living Ariocarpus dates back to the mid-1970's. A rebellious young teenager, I stood in awe in front of large field-collected Ariocarpi and Copiapoas, plants that I had only known from poorly reproduced black and white photos and terrible watercolor renditions. The plants were "not for sale" at a commercial cactus nursery in Athens that sold mostly lollipops - Gymnocalycium grafts of various colors. Unfortunately, these magnificent plants eventually joined their forefathers succumbing to the peaty-full care that was provided by the nursery people. I was left with unfulfilled desires of possession and a profound admiration for plant life.

The impression made upon me by these plants was long lasting, my obsession with Ariocarpus and Copiapoa more than 20 years later has not diminished, quite the contrary. Today, I am growing several hundreds of ariocarpi, representing over sixty different taxa, varieties and local populations, but what is more relevant to this article, all of them but one have been grown from seed in the last 8 years (Fig. 1).

Why all this romance around these modest but highly prized plants? The answer is rather simple: the genus Ariocarpus embodies some of the fundamental qualities that draw us to this hobby in the first place. These unusual plants provide a unique aesthetic, rarity, and surmountable challenge. They are living sculptures, ultimately compact and slow, rare but not impossible to find, not easy but not too difficult to grow.

Myths and Truths 

The genus Ariocarpus has been the subject of much affection and attention by growers and botanists, but also has been surrounded by many myths that persist to date which I would like to challenge from the very beginning.

1. Contrary to popular belief ariocarpi do not present any special problems in cultivation. Granted, these plants require a little more attention (or rather neglect) than your average cactus but there are many others far more difficult to grow. An Ariocarpus, if cared for properly, will grow steadily and flower reliably.

2. Cultural advice like "grow in full sun" and "give at least two hefty waterings in the growing season" (Needham, 1983) may very well explain the descriptive term "living fossils" often applied to Ariocarpus plants. In my Mediterranean climate ariocarpi certainly appreciate some shading and require as much water as all other cacti, especially if grown in clay pots.

3. "Ariocarpi are the slowest growing cacti". Well, they are particularly slow in childhood, but a 10 cm (4 inch) A. retusus can be grown in about five years, which beats many other cacti. If you want to experience "slow" try some Aztekium from seed.

4. "The minimum time to grow from seed to flowering size is probably ten years, and may well be twice that" (Weightman, 1991). Actually, A. agavoides will eagerly flower at three years from seed (Fig. 2) and most species will flower by the age of five or six years..

5. "Ariocarpus seedlings are exceptionally prone to rot." In my experience this is not true, in fact, I have come to realize that Ariocarpus seedlings benefit, more so than other cacti seedlings, from a humid closed environment during their first year of growth. This was actually the cornerstone in developing a reliable method for raising Ariocarpus from seed.

Ariocarpus de Novo 

Why grow Ariocarpus from seed? Personally I do not need persuasion on the matter - I grow everything from seed - but if motivation or justification is needed, here it is: Ariocarpus plants are not readily offered and when available they are usually small seedlings at high prices. Plants with locality data are rare but documented seed is plentiful. Furthermore there is a tremendous spectrum of varieties and forms in Ariocarpus that can be raised from seed, one look at the Ariocarpus Handbook (Sato and Suguri, 1996) should suffice to convince anybody. Advocating hybridization is sometimes frowned upon in our community, but how could one resist "creating" an Ariocarpus since all taxa within the genus can readily hybridize with each other (Neudecker, 1985). I suppose that I should include here the wild population protection argument, but I am not sure whether it is relevant any longer, I have not seen many field-collected Ariocarpus for sale recently.

The soil mix that I use for sowing Ariocarpus is my standard germination mix for cactus seed: two parts peat-based commercial potting-soil, one part loam, one part leaf mold, one part marble grit or coarse sand and one part perlite. The mix is moistened and baked for two hours. For sowing up to 20 seeds I use 5.5 cm diameter by 5 cm deep pots, for larger quantities I use either multiple small pots or larger containers 12 x 8 x 5 cm for up to 200 seeds. The seeds are dispersed on a thin layer of sowing mix mixed with grit (1:1) and should be covered to a depth that equals their diameter. After sowing the seed the pots are soaked in a bath of distilled or boiled water with fungicide (chinosol) and covered with thin plastic.

I prefer to cover the entire tray with a single sheet of transparent plastic which facilitates my weekly inspections. I am operating however with a certain degree of confidence that comes from experience, with so many seedlings under one roof a fungus attack could be disastrous. If you are just starting out it might be wiser to house pots individually in small baggies to contain possible infections from spreading.

The trays are placed under growing lights set at a 12 hour cycle. I use incandescent lights (Osram HWL-R Deluxe 160 W) which emit plenty of heat making additional heating unnecessary. If fluorescent lights are used the germination area should be kept around 25 degrees C. Allowing the trays to cool off at night (to a temperature below 18 degrees C.) is a good idea as the oscillation between day-highs and night-lows seems to stimulate germination. For these purposes it is preferable to have a separate area for germination that should be kept meticulously clean. I have an ideal situation, a small room (6 sq. metres) with a window which I use to further control the temperature - I keep it wide open in mid-winter when I sow Copiapoa and Eriosyce seed.

The first signs of germination will appear after a week but the great majority of seed will sprout between day 10 and day 20. By the end of the fourth week germination is about 90% complete (a few occasional seedlings will pop up for up to a year later). Germination rates usually range from 40 to 60 per cent for purchased seed, but are often higher for seed that I produce on my own plants. At this point the young seedlings can be mulched with a layer of fine grit (also sterilized by boiling) and should be given a light misting with sterilized water/chinosol with traces of fertilizer, which I do during inspection every 7-10 days. To compensate for the additional moisture introduced with the misting, I remove, by shaking away, the condensation that gathers on the plastic cover. This is a useful means for slowly reducing humidity after germination is complete - just take away more than you give.

Close examination at regular intervals is necessary for the first three months. During this time the seedlings are eager to grow and they will produce 2-3 tubercles (Fig. 3). If rot appears, either as fungus growing on the soil surface or worse with seedlings turning to mush (and this is not an unlikely scenario), the afflicted pot should be removed from the community, sprayed with fungicide, left out a few hours to dry, and then placed in an individual baggie and watched closely. Preventively, neighboring pots or better the entire flat should also be sprayed with fungicide and kept somewhat drier

If rot persists, the baggie method will have to be abandoned and the seedlings should be grown uncovered. This will test your tight-rope walking skills as seedlings have to be kept at the unattainable "evenly moist, but not wet" state to achieve optimal growth. I simply cannot manage this, perhaps it is my dry Athenian climate or my hectic lifestyle, invariably at some point I will err on the dry side, seedlings become thinner and darker and their growth is severely retarded, at least by comparison to the growth rates of their bagged cousins. Faster growing species may overcome this setback but young ariocarpi can be trapped in this nerve-wracking state for a long period of time. By contrast, covered Ariocarpus seedlings will remain plump and green and will progress slowly but steadily.

However, if sterile techniques are carefully observed, contamination problems, if any, are kept to a minimum and by the end of the third month you are essentially home-free: The pots should be hermetically closed in plastic either en masse or individually, and can be completely forgotten for months! No matter how tightly the bags are sealed, water molecules will slowly find their way out conveniently decreasing the humidity of the environment which may eventually require additional spraying. The young ariocarpi should be kept in this closed environment for 12 to 18 months, but not necessarily under lights, depending on space availability, the seedlings can be transferred to the greenhouse away from direct sunlight. It is best if they are uncovered during the winter months for a gradual adjustment to a drier environment. With the coming of spring some of the plants will be ready for their first transplanting and some will have to wait for up to a year more.

I transplant the seedlings into deeper community pots where they have plenty of room for their long taproot, using a more or less classic soil mix: one part soil, one part leaf mold and one part coarse material (fine marble chippings and pumice) with a bit of crushed lime added in. At this point there might be a small lapse of growth until the seedlings become established in their new environment, but after growth commences it is rapid. One can hardly keep up with potting-up especially the larger growing species like A. retusus and A. trigonus. A. fissuratus and v. lloydii are somewhat slower, while A. agavoides and A. kotschoubeyanus and its varieties stay small and may remain in the community pots until underground activity (Fig. 4) becomes obvious. Greater patience is required for the slowest taxa A. bravoanus, A. hintonii and A. scapharostrus.

Flowering Rocks

Flowers are certainly not a primary motivation for growing Ariocarpus, but they might very well become one; very few sights can compete with an Ariocarpus in full flower. A flowering rock is certainly what comes to mind. But even for the flower-snob anthesis is a desirable event, a sign of maturity and health, a confirmation of our cultural practices and a tender reward for our labor.

Having read the pessimistic reports in the literature I was prepared to wait a few decades before I would see a bud on my seed grown ariocarpi. I was therefore pleasantly shocked to see huge magenta flowers covering my A. agavoides seedlings before their third birthday! A. kotschoubeyanus and its varieties v. albiflorus, v. macdowellii and 'elephantidens' flowered the following year. Surprises kept coming every succeeding fall: A. retusus was next  (Fig 5). A. retusus 'furfuraceus' and A. trigonus (Fig. 6) after and finally A. fissuratus and v. lloydii flowered at the "advanced" age of seven. Many sowings and several generations followed and flowering times have more or less followed this pattern. Unfortunately, I cannot report on A. bravoanus, A. hintonii and A. scapharostrus the oldest of which are just three years old, but I am ready for more floral surprises.

Rocks are Forever 

Despite their reputation, ariocarpi do not present any special problems in cultivation, in fact, they are virtually indestructible - I have yet to kill an Ariocarpus over the age of two years. Grow them hard in a soil-based medium (save your peat moss for pachypodiums), give them plenty of light (but don't bake them) and only take it easy with the watering can or hose near the winter months. You will have living rocks for a very long time, perhaps longer than you can plan for.

The germination method that I use for Ariocarpus will work well for all cacti, especially for slow growing genera such as Aztekium, Blossfeldia, Obregonia, Pelecyphora and Strombocactus, with a few minor modifications will do even for Conophytum! Needless to say there are probably as many Ariocarpus germination methods as there are growers. I have developed mine based on my own experience, its major advantage is that it provides a stable environment for steady growth during the first critical year.

Other growers raise Ariocarpus from seed with a variety of methods ranging from open outdoor sowing to germinating on paper towels and then transferring to the growth medium. What will work best for you will depend on your climate, cultivation practices, personal habits, and perhaps even idiosyncrasies. The best advice is contained within a single verb: Experiment!

In closing I would like to thank all of those who have shared thoughts, experience and seed with me, effectively nullifying my geographic isolation.


Needham, L and Needham D. 1983. Notes on the genus Ariocarpus. British Cactus and Succulent Journal 1:2-7.

Neudecker, T. 1985. Crossing experiments within the genus Ariocarpus. British Cactus and Succulent Journal 3:14-17.

Sato T. and Suguri K. 1996. Ariocarpus Handbook. Japan Cactus Planning Co. Press, Fukushima, Japan.

Weightman, B. 1991. Ariocarpus - cacti for the young (or young at heart). The Cactus File 1:6-11.


---------- end of page ----------