Creating the indestructible cactus

If it's any gauge, the number of people I see on social media lamenting about their cacti turning into masses of jelly says that even with the more commonly available types, there is still a great deal of misunderstanding regarding the growing of these otherwise easily cultivated plants. And if many hobbyists, particularly the beginners, can't even get past the more standard types, then how can we expect the cactus scene to develop further? In many plant bazaars, I frequently see people huddling over some rather pricey specimens only to overhear them say "I can't even keep most of my cacti alive, so if I buy that, it would just be like throwing away my money." It's not atypical to find stalls still displaying so many of their offerings on the final day of a plant show. And no, it's really not about the price of these plants as even the more expensive ones are still within the range of most collectors. It's about the experience of the vast majority of the people in keeping cacti.

That having said, let it be known that this post is intended for hobbyists especially the beginners. But if you're a producer, you might find some useful bits too so you are most welcome to continue reading.

This is the Rebutia that I used in my February lecture, to illustrate how I pot my cacti. Of course, it's so plump it looks like any regular store-bought cacti. But it only looks like that because we have had rains for almost two consecutive weeks. During dry stretches, the ribs become more prominent. If I keep it well-fed and watered throughout the year then it will succumb due to too much distention. Allowing your plants to shrink during dry and hot spells will ensure that they have enough spaces inside their bodies to accommodate plenty of moisture during rainy periods.

For the past few years, I have been advocating the use of a heavily inorganic mix for cacti, and much of the more salient information has already been tackled in earlier, similar posts. However, this philosophy of using mainly rocks as the medium is easily lost in a miasma of often conflicting information hovering around the internet and horticultural circles. Has the philosophy gained widespread traction in these past few years? Not at all, I would say. Last February I had the utmost pleasure to deliver a lecture at one of the horticultural events that took place in Quezon City, and in it, I discussed the basic tenets of the philosophy, which in essence is a very stripped down, back-to-the-basics approach in keeping cacti. And an important component of this philosophy is to look beyond the nurseries of the producers, and out into how these plants live in the wild. Because as so often happens in the cactus scene, hobbyists take enormous considerations about how these plants are produced in great numbers in growers' nurseries, but become befuddled when the same plants perish in just a few weeks or months under their care. If your growing space is much like a nursery with a functioning greenhouse and all the trappings, then, by all means, keep your plants like any grower would. If you don't, then fine-tune your cultivation methods. At this juncture, it is imperative to establish that:

Nursery plants= pampered
Wild plants= in a constant battle to keep alive

Seed-grown Opuntia. I typically encourage fertilizing columnar types as well as opuntias because of their higher nitrogen requirements needed to support the vertical growth, but this one does fine without nutrient supplementation.

A solitary Lobivia arachnacantha, otherwise clump-forming. I have accidentally discovered that cacti known for producing multiple pups will do so very sparingly when maintained on rocks. One possible reason is that due to the limited nutrients available, plants will concentrate those for its own use rather than on offsets. 

If your plants don't have protection from swings of temperatures, heavy rains in extended periods, merciless sun, or other vagaries of nature, then adopt a 'wild' mentality. Get back to the basics. And the basics say that a great majority of cacti living in the wild, with the obvious exceptions of the forest species living as epiphytes, grow on rocks. Stop thinking of rocks as inert- rocks are THE nutrient sources! And they provide just the right amount of nutrients that your plants need. Baby your plants if you like, but if you want them tough, then make them tough. To be very honest here, the cacti are my most neglected plants. I grow species orchids, aroids, aquatic plants, begonias, gesneriads, gingers, a few palms and cycads, hoyas, dischidias, tropical ceropegias, and other oddballs. Many of these are not easy to cultivate. And I also keep animals. And I have a family to attend to. So I want my cacti to be so tough they will just smirk at napalm. I want them to sit in just one spot all throughout the year. Of course, I can put shade cloth and afford them protection, but why would I? My cacti are lean and mean, not spoiled couch potatoes.

If you're a follower of this blog, you surely have seen previous photos of this clump. As it turned out, it's a Frailea. 

This Turbinicarpus schmiedickeanus subsp. klinkerianus exhibits the lean, pine cone-like appearance of plants when grown in an inorganic, rocky mix.

But at the risk of being repetitive, I urge you to click the following links for my previous articles regarding the topic at hand:

A step by step guide on potting cacti on mineral soils, P.1
https://jardinerongsunog.blogspot.com/2018/03/a-step-by-step-guide-on-potting-cacti.html

A step by step guide on potting cacti on mineral soils, P.2
https://jardinerongsunog.blogspot.com/2018/03/a-step-by-step-guide-on-potting-cacti_7.html

A rocky argument
https://jardinerongsunog.blogspot.com/2018/03/a-rocky-argument.html

Materials for an inorganic cactus and succulent mix
https://jardinerongsunog.blogspot.com/2018/06/materials-for-inorganic-cactus-and.html

A couple of ferocacti seedlings. For obvious reasons, I use sand to accommodate the fine roots of young plants, but soon move them to a purely rocky mix once the roots have sufficiently developed.

Cheap but not disposable is this very inexpensive Mammillaria thriving with a healthy dose of neglect. The rocky mix made it possible.

And at this point, I think it would be easier for me to address some concerns regarding the matter using a Q and A format.

Do you air-dry cacti before putting them on a rocky mixture?
I see no reason for doing that. For as long as you don't damage a great deal of the roots, then air-drying is just a waste of time. Air-drying though is recommended when repotting mature Ariocarpus.

I grow my cacti on rocks, but still many of them rotted away. What went wrong?
What rocks did you use? If you used the wrong types of rocks- for example, limestone, coral rocks, and other highly alkaline rocks- then the undesirable components of those rocks will accumulate in your cacti's tissues until it is overwhelmed. It can take a few months, even years. But the core idea is this: most cacti grow on slightly acidic substrates. Very few actually grow on limestone or gypsum (aztekiums come to mind). Again, try to research your plants' ecological needs.

Can all cacti be grown on pure rocks?
Nope. A few species need humus. But the majority of cacti can and will grow on just rocks.

Can I fertilize my cacti?
Of course, you can. But in addition to a fertilizers' positive effects, you have to be aware of its downsides too, especially with regards to cactus physiology. Think of the entire cactus plant as a storage organ. During its millions of years of evolution in harsh, unpredictable environments, the entire plant had to cope in often ridiculous periods of lean times. So it absorbs all the nutrients and water it possibly can. But both are often perpetually in short supply, so the cacti have evolved to keep itself alive even with so little to go by. Under cultivation, we are the magical providers of nutrients and water, and in these circumstances, cacti will absorb whatever they can in preparation for the lean times that never comes. So all the nutrients and water are stored in the cactus body, and being caring individuals that we are, we continue supplying the plant with more of the good stuff. Now let us use your own organ as an example: your stomach. Eat and drink all you can, but you know that there is a limit to what you can take. Try biking on a distended stomach, or maybe even take a simple bus ride. Tell me what happens next. It's the same with cacti. These plants can and will take all they can, but it only takes minimal outside pressure- be it a day's worth of rain or just a few days of desiccating sun- before your beloved cactus departs to mush-land. Because you see, a cactus that looks like a spherical accordion in its native habitat but has assumed a watermelon-like figure in cultivation has its epidermal cells extremely thin due to too much stored nutrients. What happens to a balloon if you prick it with a pin? That's right, it bursts. Do the same to a basketball. Good luck with that. So aim for toughness, not for fatness. If you feel you must fertilize, do so sparingly. Thin epidermal cells are for sissies, and if you grow your plants tough then their epidermal cells will thicken enough to withstand heavy rains and brutal sun, as well as pathogenic attacks. I said this before and will say it again: obesity is never a sign of health.

Can all cacti be kept 'tough'?
No. Again, ecological knowledge of your plants is highly important. If you have a high altitude species but you are in the hot lowlands, then common sense dictates that you have to put extra attention to it. Many cacti with woolly covering are from higher elevations, so keep that in mind. Furthermore, there are cactus species that somewhat prefer shade. Similarly, a Copiapoa (for example) that has evolved with so little precipitation in the deserts of Chile will find your monsoonal climate a challenge. Using rocks is only half of the story. Knowledge of the plants' ecology completes it.

I don't like the unnatural look of a grafted cactus. Is there a way to grow them in their own roots?
Grafting came into being for people to be able to grow the so-called more difficult species, but I believe this to be a reflection of using the wrong soil than the plants being truly 'difficult'. Take for example, Aztekium. It has very specialized soil needs as it grows on gypsum in the wild. Use a medium that is totally different from gypsum and you have altered what is natural for the plants. Sure, if one doesn't know that aztekiums grow on gypsum then isn't it much easier to just graft them on a Cereus or a Myrtillocactus? But personally, I don't like grafted plants either, with the exception of those with extremely little or no photosynthetic tissue like the hundreds of colorful gymnocalyciums you see everywhere. Grafting is more like cheating to me, and it takes away the challenge. But that is just my opinion. Grafting is great for producers, however, because grafting promotes faster growth and the production of more pups.

Will more expensive plants grow well on rocks too?
For one, I see no correlation between a plant's price and its ease or difficulty of cultivation. A plant that is expensive in one region may be quite cheap in another, so the words 'pricey' and 'expensive' are both relative. Price doesn't necessarily dictate a plant's cultural difficulty. Whatever the price is, for as long as you don't do things right, it will not prosper.

My plants are being overrun by mealybugs and ants. What should I spray them?
Try rephrasing the question to: what can I do so they don't appear in the first place? Ants farm mealybugs. So get rid of ants and you have solved the mealybug problem. Ants love sand and other fine materials, such as clay. So don't use sand. I have found out that pumice sand is much less attractive to ants than river sand (construction sand), but in so many cases, you can get away without sand anyway. I often use laterite in my mixes, which is essentially red clay, to introduce iron. But the ratio is negligible. So no, my cacti don't have ants AND mealybugs. Why spend money on chemicals when you can dissuade ants from establishing in the first place? Prevention is better than cure.

Is there a market for tough cacti?
I think so. But because production will be slow, it might jack up the prices higher than if the plants were pampered. Still, I think there is a niche market still untapped here.

In a nutshell, growing cacti on rocks bring about two benefits: the plants become tougher and their appearances approach those of wild specimens. So many cactus species appear very differently from their wild counterparts and if you're one of those who like things very natural, then this approach is for you. If, on the other hand, you prefer large, plump plants (such as ariocarpi looking like tuberculated balls instead of being flat), then a nutrient-rich mix with frequent fertilizing is the key. It all depends on tastes. And in whether you want your cactus to become well-built warriors or touchy primadonnas.

A couple of young wilcoxias. Over-watering is the bane of these plants, but these two have so far survived the incessant rains we had these past weeks. Let's see how far they can go.