A step-by-step guide on potting cacti on mineral soils, P.1
In this post I am going to illustrate one of the ways I pot recently purchased cacti. And for this purpose, I will be using this plant, bought just two days ago (Monday), as an example. You can see that, as with most nursery-grown plants, the substrate used is mainly organic- leaf litter, to be exact.
1. One of my biggest hang-ups with nursery grown succulents in the Philippines is that most of the sellers do not know the names of their produce. I assume the plant at hand is a Melocactus, and for our first step we need to find habitat photos of melocacti. If you do not know the species name of your plant, worry not. You just need a loose blueprint, so to speak. Below are two screenshots from the e-zine Cactus Explorer No. 18, published April of the previous year, with an account entitled A brief history and visits to the habitat of Melocactus matanzanus. Note the prevalence of gray, serpentine rocks (rocks heavily laden with heavy metals) and other crushed aggregates. I do not know the exact composition of the soil, but from my observations when I hike through ultramafic habitats within the Philippines, where serpentine dominates, the 'soil' is actually finely eroded deposits from inorganic sources. Because the population of these M. matanzanus, as featured in the article, is within a forest type known there as cuabal, or a thorny, scrubby forest type that is typical of serpentine habitats there, some leaf litter is found atop the soil. This indicates that nitrogen is probably sourced from decomposing organic matter, although the process is probably slow compared to forests from higher rainfall areas.
You do not have to exactly imitate everything- that would be the territory of another philosophy called the WiG (Wild-grown) Style.
2. When potting or re-potting succulents, be very careful not to disturb the roots too much; among cacti, Melocactus comes to mind as being one of those genera that contain species that can be very touchy when their roots are interfered with, and amongst succulents, stapeliads. Lightly press the sides of the current container (in this case a seedling pot which lends itself very well for this action) to loosen up the soil before turning it over. Tease off as much soil as you can but leave those that are clearly adhered to the roots. This serves two purposes: 1. because the plant will be moved to a heavily mineralized mix, some remaining organic matter will help the plant sustain itself while it is acclimatizing to the new conditions, and 2. removing way too much of the old mix will invariably stress the plant.
3. The container we will be using is a tall clay pot that is about 7.5 inches tall by 6 inches in diameter. This brings us to a very important consideration when potting or re-potting cacti: over-pot them. As I said above, there are plants that resent root disturbance, and using a large pot practically eliminates the need to re-pot them in the future. Furthermore, a larger pot allows for the development of roots. In horticulture, what gardeners really have to care of is the roots above all else. The state of these sub-soil plant parts dictate the health of the plant as a whole. There is one drawback when using larger pots though: cumulatively, these pots take up a lot of space. This means fewer plants in the long run. Admittedly, my own gardening space is pretty limited too, with much of the horizontal space taken up by non-succulents (mostly those bratty Amorphophallus). And, to maximize the amount of light that each succulent receives, I do not use racks. However, my priority when I acquire plants is their general well-being. I do not mind if I have a very limited number of plants for as long as I know I am growing them well. Likewise, I do not force plants to remain small. When you think about it, they really have no choice to whom they will end up with. We do the choosing. We do the acquiring. Therefore, we owe it to these plants to provide them what they need once we have taken them home. This reminds me of those small homes with smaller front yards that in reality can only accommodate a small shrub but is planted with an Araucaria or two. The poor trees just languish. It's just silly and irresponsible. In my place, it is I who do the adjusting, not my plants. If you cannot handle the eventual mature size of the plant, look for something else. Take them for what they are.
Alright, I am beginning to sound like a philosophy teacher now. Which should come as no surprise because I used to teach philosophy anyway. Moving on...
As you can see on the photo below, the pot is filled a third up with ordinary gravel and broken pots. I call these 'extenders' and only serve the purpose of filling up bottom space instead of using a thoroughly mineral mix throughout, which can be quite expensive and rather in short supply at times. For succulents I have no qualms of using chunks of styrofoam. The difference in approach can be explained by the fact that I do not fertilize cacti, but do so with the other succulents (cacti are succulents too, however). Styrofoam is inert and roots derive nothing from them nutritionally, but it is compensated by fertilizing. I can use styrofoam for cacti too, but doing so may compel me to also fertilize these plants.
4. Here is an overview of the media I am using for the plant. On the left is a mixture of S1 and pumice sand, and on the right is an un-graded aggregate I bought yesterday from a local pet shop. Above these are sedimentary rocks, probably sandstone (?) and also bought from the same said pet shop. Unfortunately, I do not know the exact name of these rocks. The ubiquitous pumice stones are not used in this set-up.
I mix the S1/pumice sand mix with the aggregate, but separated the larger pieces of the latter, to be used later. For the purposes of this article let us call this portion of the mineral mix, the 'body', because it constitutes the bulk of the entire mix.
5. When the level of the 'body' is deemed sufficient enough, we sit the plant on top, with its roots held in place by the larger aggregates we separated from the main mix, and the larger sedimentary rocks (?). Constricting the roots has one distinct advantage: in nature, many cacti are said to have their roots growing on cracks within the soil and when emulated in cultivation, has been observed to develop a much more branched aspect. As you probably know by now, I put a lot of premium on the well-being of the roots. Furthermore, placing larger rocks around the plants' bases allow for better air circulation and helps in the avoidance of problems normally associated with stuffy conditions around the coll (the cactus plant's base), such as rot. Note however that in cacti known to bury themselves in the ground (Ariocarpus, Astrophytum, Escobaria, and Frailea, among others) using large pieces of rocks very close to the coll may be counter-intuitive.
6. Using the remainder of the 'body', we fill the pot up, up to the edges. As you will see, I have included some leaf litter and even decomposing twigs. These were of course sourced from the plant's former mix. Dust can be observed clinging to the cactus' body.
The old mix also contained pieces of chunky sedimentary clay. These were crushed by fingers and layered on top of the new mix. One must be careful not to crush the particles too finely or water may accumulate when the rainy seasons comes in full swing.
Here the plant is situated underneath the light shade of an oregano. The plant is dry enough to be placed under the sun, but the soil mix is still rather moist, as evidenced by the rocks that are still quite darkened.
The entire enterprise, including the finding of appropriate habitat photos, took me almost an hour to finish, which is longer than what others would typically spend with when potting their plants. My process, like the actions of nature, can be quite slow. But the long-term result is very much worth it. When the rainy period reaches its peak come August, mosses and possibly also selaginellas will appear and these will be welcome additions to the set-up as they will absorb excessive moisture and thus protect the plants from any threat of rotting. By the next dry season, the mosses will dry up and enter dormancy, only to revive again come the next season of torrential downpours. This cycle is typical for my other succulent plants.
Stay tuned for P.2!
1. One of my biggest hang-ups with nursery grown succulents in the Philippines is that most of the sellers do not know the names of their produce. I assume the plant at hand is a Melocactus, and for our first step we need to find habitat photos of melocacti. If you do not know the species name of your plant, worry not. You just need a loose blueprint, so to speak. Below are two screenshots from the e-zine Cactus Explorer No. 18, published April of the previous year, with an account entitled A brief history and visits to the habitat of Melocactus matanzanus. Note the prevalence of gray, serpentine rocks (rocks heavily laden with heavy metals) and other crushed aggregates. I do not know the exact composition of the soil, but from my observations when I hike through ultramafic habitats within the Philippines, where serpentine dominates, the 'soil' is actually finely eroded deposits from inorganic sources. Because the population of these M. matanzanus, as featured in the article, is within a forest type known there as cuabal, or a thorny, scrubby forest type that is typical of serpentine habitats there, some leaf litter is found atop the soil. This indicates that nitrogen is probably sourced from decomposing organic matter, although the process is probably slow compared to forests from higher rainfall areas.
You do not have to exactly imitate everything- that would be the territory of another philosophy called the WiG (Wild-grown) Style.
2. When potting or re-potting succulents, be very careful not to disturb the roots too much; among cacti, Melocactus comes to mind as being one of those genera that contain species that can be very touchy when their roots are interfered with, and amongst succulents, stapeliads. Lightly press the sides of the current container (in this case a seedling pot which lends itself very well for this action) to loosen up the soil before turning it over. Tease off as much soil as you can but leave those that are clearly adhered to the roots. This serves two purposes: 1. because the plant will be moved to a heavily mineralized mix, some remaining organic matter will help the plant sustain itself while it is acclimatizing to the new conditions, and 2. removing way too much of the old mix will invariably stress the plant.
3. The container we will be using is a tall clay pot that is about 7.5 inches tall by 6 inches in diameter. This brings us to a very important consideration when potting or re-potting cacti: over-pot them. As I said above, there are plants that resent root disturbance, and using a large pot practically eliminates the need to re-pot them in the future. Furthermore, a larger pot allows for the development of roots. In horticulture, what gardeners really have to care of is the roots above all else. The state of these sub-soil plant parts dictate the health of the plant as a whole. There is one drawback when using larger pots though: cumulatively, these pots take up a lot of space. This means fewer plants in the long run. Admittedly, my own gardening space is pretty limited too, with much of the horizontal space taken up by non-succulents (mostly those bratty Amorphophallus). And, to maximize the amount of light that each succulent receives, I do not use racks. However, my priority when I acquire plants is their general well-being. I do not mind if I have a very limited number of plants for as long as I know I am growing them well. Likewise, I do not force plants to remain small. When you think about it, they really have no choice to whom they will end up with. We do the choosing. We do the acquiring. Therefore, we owe it to these plants to provide them what they need once we have taken them home. This reminds me of those small homes with smaller front yards that in reality can only accommodate a small shrub but is planted with an Araucaria or two. The poor trees just languish. It's just silly and irresponsible. In my place, it is I who do the adjusting, not my plants. If you cannot handle the eventual mature size of the plant, look for something else. Take them for what they are.
Alright, I am beginning to sound like a philosophy teacher now. Which should come as no surprise because I used to teach philosophy anyway. Moving on...
As you can see on the photo below, the pot is filled a third up with ordinary gravel and broken pots. I call these 'extenders' and only serve the purpose of filling up bottom space instead of using a thoroughly mineral mix throughout, which can be quite expensive and rather in short supply at times. For succulents I have no qualms of using chunks of styrofoam. The difference in approach can be explained by the fact that I do not fertilize cacti, but do so with the other succulents (cacti are succulents too, however). Styrofoam is inert and roots derive nothing from them nutritionally, but it is compensated by fertilizing. I can use styrofoam for cacti too, but doing so may compel me to also fertilize these plants.
4. Here is an overview of the media I am using for the plant. On the left is a mixture of S1 and pumice sand, and on the right is an un-graded aggregate I bought yesterday from a local pet shop. Above these are sedimentary rocks, probably sandstone (?) and also bought from the same said pet shop. Unfortunately, I do not know the exact name of these rocks. The ubiquitous pumice stones are not used in this set-up.
I mix the S1/pumice sand mix with the aggregate, but separated the larger pieces of the latter, to be used later. For the purposes of this article let us call this portion of the mineral mix, the 'body', because it constitutes the bulk of the entire mix.
5. When the level of the 'body' is deemed sufficient enough, we sit the plant on top, with its roots held in place by the larger aggregates we separated from the main mix, and the larger sedimentary rocks (?). Constricting the roots has one distinct advantage: in nature, many cacti are said to have their roots growing on cracks within the soil and when emulated in cultivation, has been observed to develop a much more branched aspect. As you probably know by now, I put a lot of premium on the well-being of the roots. Furthermore, placing larger rocks around the plants' bases allow for better air circulation and helps in the avoidance of problems normally associated with stuffy conditions around the coll (the cactus plant's base), such as rot. Note however that in cacti known to bury themselves in the ground (Ariocarpus, Astrophytum, Escobaria, and Frailea, among others) using large pieces of rocks very close to the coll may be counter-intuitive.
The old mix also contained pieces of chunky sedimentary clay. These were crushed by fingers and layered on top of the new mix. One must be careful not to crush the particles too finely or water may accumulate when the rainy seasons comes in full swing.
7. Dried leaves from Ficus benjamina is used to finish the set-up. Then everything is sprayed heavily to wash down the accumulated dust on the plant's body and to settle the mix, particularly around the coll.
Here the plant is situated underneath the light shade of an oregano. The plant is dry enough to be placed under the sun, but the soil mix is still rather moist, as evidenced by the rocks that are still quite darkened.
The entire enterprise, including the finding of appropriate habitat photos, took me almost an hour to finish, which is longer than what others would typically spend with when potting their plants. My process, like the actions of nature, can be quite slow. But the long-term result is very much worth it. When the rainy period reaches its peak come August, mosses and possibly also selaginellas will appear and these will be welcome additions to the set-up as they will absorb excessive moisture and thus protect the plants from any threat of rotting. By the next dry season, the mosses will dry up and enter dormancy, only to revive again come the next season of torrential downpours. This cycle is typical for my other succulent plants.
Stay tuned for P.2!
Great post! The way you explained was easy to understand and very helpful. Looking forward to more content like this!
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