Hated, mistreated, seen with contempt, often carefully avoided. Expanded clay and peat are two highly contested and criticized elements among growers of succulent plants and cacti in particular. Net of the chatter from the Internet, are these really two materials that should be forgotten with the cultivation of this type of plant? The question remains open and every grower has his reasons, but there is a fact: on the Net, as far as expanded clay and peat are concerned, everything is said. Above all, it is said that they retain humidity excessively and for this reason they should be banned from the cultivation of cacti and succulents in general. It is said that they favor the onset of rot, that they do not let the roots breathe and much more. Why then do many serious nurserymen (and expert growers with them) still make extensive use of those elements? Simply because, as in many factors of cultivation, the point is not so much the material itself, but the type of use that is made of it.

In this article, let’s try to understand if expanded clay and peat are really such “dangerous” materials for cacti and succulents, if and how they can be used and what their real pros and cons are. (…)

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L'articolo Expanded clay and peat: are they really two materials to avoid when growing succulents? proviene da Il fiore tra le spine.

Full sun? But what do you want to know, the window on the landing is enough! Substrate? I buy it ready at the supermarket, it’s perfect. The pots? The smaller the better: never leave more than half a centimeter between the plant and the edge of the pot… And so on, by dint of amenities, false beliefs, hearsay phrases that rapidly becomes dogma because… because it was said by that guy on Facebook and it’s immediately clear that he’s someone who knows about it because his videos has the right lights and Kubrick seems to have done the editing for him. Joking aside, how much nonsense do we still have to hear today about the cultivation of cacti? How many improvised “influencers” ride the crest of social media driven by the Mistral of likes (yes, likes, which in jargon are called “the metrics of vanity”…) and, supported by legions of followers and big thumbs up, they deliver lessons and conferences winking from the monitors, revealing “5 fantastic tricks you don’t know about cacti” or “how to go from seed to flowering plant in 35 seconds”. Or, with an attitude halfway between the conspiratorial and the revealer of esoteric secrets, they promise to teach you everything, absolutely everything about the cultivation of these splendid plants. Then, perhaps, you dig a little and discover that the influencer on duty has been growing cacti for 2 or 3 years – a gift from grandmother -, keeps them next to the PC or television (“you know, they absorb magnetic rays”), he can’t distinguish a Rebutia from a Begonia and has never bothered to leaf through any book on cacti and succulents. There are also influencers for plants, right? No. There are likeable and well-prepared characters, there are pretty faces who know something, but there is also a lot of “fluff” (forgive the old reporter’s term). So much wrong information, so much confusion and so much unpreparedness.

So, without any desire to offer you “The Word” with this article, here is a handbook, a list of ten things you need to know (or you should already know!) if you really want to cultivate your cacti in the best possible way. Without tricks or deceptions: here we are at the fundamentals, come on. But without these you go nowhere. And I am convinced that even those who, scrolling through the 10 points will say “ah yes, I know” ten times, will find in this handbook a useful tool for reviewing, asking themselves a few more questions and pushing themselves to improve. And rest assured, what follows does not come from the web, but from 30 years of experience in the field, of experiments and failures, from discussions with growers and scholars far more expert than me and from reading a few dozen manuals in Italian, English, French, Spanish (and also German, although in that case, I confess, I limited myself to photographs and captions, not knowing the Teutonic language!) (…)

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L'articolo How to grow cactus: the handbook with the 10 things you absolutely need to know to avoid mistakes proviene da Il fiore tra le spine.

Recently, on the social channels connected to the site, I published a short video in which I repot an Astrophytum asterias in a substrate composed solely of Seramis. Following that video, many asked me for information on this particular material with its characteristic orange colour, in fact little used in the cultivation of succulents and not easily available in small nurseries. I have had the opportunity to use Seramis in the past in the cultivation of some cactaceae and my experience has been decidedly positive (although, as a porous inert material, in my opinion pumice remains the best material ever) and it is also for this reason that I recently employed it for the Astrophytum subject of the video (video that you can also find at the end of this article).

Answering many questions received in recent weeks, let’s see in the following article what exactly Seramis is, what are the strengths and weaknesses of this material and what can be its use with succulents and, in particular, with cacti. (…)

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L'articolo Seramis, an alternative material for growing cacti and succulent plants: pros and cons proviene da Il fiore tra le spine.

In this article we see how to make a proper substrate for use with any genre of cactus and, with appropriate adjustments, with succulents, in general. We will make it, and this is the point of this article, with materials that anyone can now easily find in any place (…).

Introduction

One characteristic that any substrate for cacti and succulent plants, in general, must have is the ability to drain water and dry quickly. It is the starting point, the end to which we must strive if we want to make good potting soil for succulent botanical families. The materials we can use are virtually limitless and can also vary according to the type of cultivation we want to pursue. Spartan cultivation to obtain plants similar to those in the wild, “push” cultivation to have plants that are swollen and “immaculate-looking,” “maintenance” cultivation, that is, with no particular purpose other than to grow the plant properly, etc. The combinations we can make with various materials are virtually endless and, theoretically, we could try to prepare a suitable substrate for each individual species that we intend to grow. Each plant has its own specific needs, and even among cacti, there are the species that want more organic material, others that want exclusively mineral potting soils, others that require lime substrates, and so on.

Of course, this fact opens the door to experimentation, which I recommend to anyone who has the time, desire and curiosity to test various substrates to figure out which is the best formula for this or that kind of plant (obviously in combination with the other growth factors, such as water, exposure, temperatures…).

Here you will find an article related to one of the experiments I have done over the years.

The “common” materials

After this long introduction, going back to the purpose of this article, which is nothing more than to provide basic directions for making proper soil for cacti and succulent plants using only materials readily available in any nursery and building materials retailer. Yes, because while it is true that online we can buy (up to certain quantities, of course), peat, quartzite, gravel, sand, gypsum, pumice, and lapilli of all colours and sizes, as well as potting soils specially made for cacti or succulent plants, it is equally true that good compromises can be made with “common” materials, especially if you don’t want to have too many problems.

Field soil and marl deserve a separate discussion. Field soil means clay, which can be more or less calcareous, more or less sandy, and more or less rich in nutrients. In short, there are endless types, and the best way to know whether or not that field soil, mixed with aggregates such as gravel, pumice, and sand, is suitable for cacti is to experiment with it for at least a couple of years. We can say the same thing for marl, a material exceptional for growing different kinds of cacti (if you are unfamiliar with marl, find a specific article here). Marl is almost impossible to find commercially, and even when you get it, you should be careful because there are various types, and not all of them are good for cacti.

Learn more about using field soil and marl in cactus substrates in this specific article.

The classic mix

A first viable option for those who want to avoid problems, as I have written on several occasions, is the traditional mix of equal parts lapilli, pumice and peat. It is the most popular potting soil for growing cacti and succulents, especially in skilled nurseries. In principle, it gives good results with all cacti, even working very well for leafy succulents (e.g., Crassula, Echeveria, etc.) simply by adding a little peat or earthworm humus, to make the substrate a little richer organically. Pumice and lapilli usually come in sizes between 3 and 7 millimetres, and this type of substrate is easily found online or at skilled nurseries. Unfortunately, it is not yet found commercially in all nurseries or gardens that do not specialise in succulents.

This is the article’s main focus because this substrate can be made without difficulty by retrieving materials from any large nursery or garden store.

First of all, the peat. It is the organic component of the substrate that contains the nutrients needed by plants. Most cacti, in nature, live in organically poor soils, which is why in the correct substrates intended for these plants peat should never be prevalent. Again, peat retains moisture for a long time, while the basis of a valid substrate for succulents, as we have seen, is the ability to drain water and dry quickly. For these reasons potting soils intended for cacti, it’s a good idea not to use peat percentages of more than 40 per cent. With some species, particularly those with “taproots” (e.g., Ariocarpus), the amount of peat will have to be decidedly small: a maximum of 20 per cent of the total. On the contrary, in leafy succulents is correct to provide at least 50 per cent peat because these plants need more organically “rich” potting soils. At the same time require greater amounts of water than cacti (their substrate will therefore have to remain moist a little longer to allow the roots to absorb the necessary water).

Peat can be found in any nursery: in fact, it is the material that makes up all so-called ‘universal potting soils’, i.e. intended for any genre of plants. At the same time, peat is the basis of all other packaged potting soils that we find in gardens: from those for citrus trees to those for ornamental plants, turf, acidophilic plants, and aromatic plants. All these potting soils are composed mainly of peat (there can be different types, but it is always peat) and, as appropriate, small percentages of sand, perlite, or pumice. The only potting soil not to be considered with succulents is orchid-specific potting soil, which contains no peat (or very little of it) and is composed mainly of bark.

The same ready-made potting soils for cacti and succulents are nothing more than peat with a little sand, pumice or perlite. On their own, they are no good, but they can be considered on par with peat or universal potting soil, with the advantage that they will already contain some sand, perlite or pumice.
For the rest, one ready-made potting soil is as good as another: what matters is that it is of good quality and that the peat is fine and not rich in filaments, bark, timbers, and other things. If we want to be precise and have a choice, we use blond sphagnum peat, which is slightly acidic and is fine for most succulents.

As an alternative to peat, since from a sustainability point of view, its consumption on a global level has become excessive in recent years, one can use earthworm humus, which can be found in all nurseries.

The other two elements of the traditional mix are pumice and lapilli. You can find both in well-stocked gardens, with one “flaw”: the size is almost always coarse, around 10 millimetres. There are no problems if you have to re-pot large succulents. But if you have seedlings to be placed in 5 or 7-centimetre pots, there are two alternatives and you have to be patient: you can either sift the material keeping the smaller part, or you can use the hammer (with a greater dose of patience) and break pumice and lapilli into smaller pieces. Of the two materials, in my experience, pumice is best, simply because it dries faster. With these three elements (universal potting soil, pumice, lapilli), we can already make a perfect substrate that is very popular in growing cacti and succulents. Mix well one part peat (as a unit of measurement, you can use the scoop) with one part pumice and one part lapilli, and the substrate is ready. If it is intended for leafy succulents, add a couple of scoops of peat to the final mix; if you intend to use it for “mangy,” very moisture-sensitive cacti, reduce the amount of peat by half.

The ‘simple’ mix

A valid alternative to the classic pumice/lapillus/peat mix, which can also be found for sale online or in large bags at some nurseries specialising in succulents, is the potting soil that I have prepared in the video published below. It is an even simpler but perfect substrate for almost all cacti and succulents, which I use when I finished my specific mixtures. Again, the starting point is peat. If the universal potting soil is of good quality, there will be no need to sieve it because it will not have any residual bark, coconut fibre, wood and other ‘impurities’. Good quality universal potting soil, it bears repeating, is usually peat of two or three types already sieved fine (and even this is fine because we will be adding the ‘coarse’ part to the compost), and added with a little pumice or, more often, perlite.

To one part peat, we add one part pumice and half a part fine sand, and the substrate is ready. As I have written before, the pumice we find in gardens is usually coarse-grained but can be sieved or crushed if necessary. Sand, on the other hand, is easily found at building material dealers. Caution: it must be river sand, preferably silica sand. Avoid sea sand. As I pointed out, in this substrate to one part peat and one part pumice I add only half a part sand because fine sand is only very useful in small quantities. If we were to make potting soil with only fine material (sand, pure peat or pumice powder, for example), we would create a potential succulent ‘killer’. In fact, after a few waterings, the substrate would compact and remain constantly moist, causing asphyxiation and root rot. Therefore, it is essential to have both a fine part (useful for rooting) and a coarse part in the substrate, which can make the soil ‘loose’ and increase its drainage capacity.

As I explain in the video, we can make small changes to this mixture if necessary so that it is also perfect in specific cases. For example, if we have to re-pot leafy succulents or hardy plants such as Echinopsis or epiphytic cacti such as Epiphyllum or Schlumbergera we can increase the amount of peat a little (add a couple of shovelfuls at the end and mix everything well). On the contrary, if we are dealing with delicate, slow-growing and particularly sensitive to stagnation plants such as Ariocarpus, Pelecyphora, Aztekium, Copiapoa and others, we can halve the amount of peat and add gravel or quartzite to the substrate.

The latter are also readily available materials in any city. Gravel (with a grain size of between 3 and 5 millimetres) can be found at building material dealers, often mixed with sand. In these cases, with a bit of patience and a fine-mesh sieve, you will be able to separate the sand from the gravel and thus be able to use them in separate dosages. On the other hand, quartzite can be found in aquarium shops or pet shops. There are countless types of quartzite: it can be bought in various sizes and colours. Just be sure it is not “treated” or in any way coloured material.

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How much light do cactus need? A summary table
How to repot cacti and succulent plants
Substrates for cacti and succulents
The correct soil: the materials you can use
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© The texts, videos, photos and graphic elaborations of the site “Il fiore tra le spine” are original material and are covered by copyright. It’s forbidden to reproduce them in any way.

L'articolo A good cactus potting soil with materials readily available in any nursery? Here is how to do it proviene da Il fiore tra le spine.

The use of marl as a substrate component for the cacti’s cultivation has been widespread for years, especially in Italy. Thanks to the studies and research conducted by my friend Andrea Cattabriga – grower, researcher and succulent expert at the international level. But what are we talking about, when we discuss marl? Quite simply, a greyish and highly friable rock, to the point of breaking up into flakes until it becomes powder. It’s used to create substrates for the cultivation of many cacti and some succulent plants when combined in some dosages with other materials such as quartzite, pumice, sand, gravel, lapilli, peat, field soil (clay).

In this article we explore the benefits of using marl in cactus cultivation, we see how to make a valid marl-based substrate, and we try to understand, above all, with which kinds of cacti this material can work and with which ones it should be avoided. (…)

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L'articolo Marl as a substrate for cacti: is it really so good? How to use it and with which plants does it work proviene da Il fiore tra le spine.

We look at the benefits of repotting cacti and succulents over the winter in the article that follows. (…)

Repot in winter: the advantages

By repotting in winter, the plants are completely still (except for those that grow even in the cold like Pediocactus and some Escobaria, for example) and the soil is completely dry and it is easy to clean the roots well, where needed. If the soil in which the plant is found is already correct and if I have decided to use the same type of soil for that plant, I simply shake the earth a little to free some roots and check that the root system is in good condition and does not contain parasites. It is essential that the new substrate is dry or, at most, slightly damp. Another important aspect deriving from the choice of the winter months for repotting is in fact this: until the end of March the plants will not receive water and the roots will have plenty of time to heal. Some injury to the secondary roots is almost inevitable during repotting and, in the event of a change of substrate with thorough cleaning of the root system (for example if the plant was in peat) it can easily happen to break or injure even the primary roots. Similarly, in the event of a total change of soil or a suffering plant, it may be necessary to drastically shorten the roots by cutting them. For all these reasons, winter repotting is preferable. This is a guideline, not a rule, though. In fact, cacti and succulents in general can be easily repotted even when they are in full vegetation, as well as when they are in bloom. In these cases, however, it is important to repot in dry soil and wait at least two or three weeks before watering, keeping the plant in a bright place but not in direct sunlight.

Wait or repot immediately?

Many wonder if it is necessary, once a plant has been flared (in winter or in summer, the substance does not change), to leave it bare root for some time or if it can be repotted immediately. Let’s say that leaving the plant with the roots in the air, in a place sheltered from direct light, is certainly a good precaution. In this way we will be sure that any injuries or cuts to the roots will heal perfectly. From what I’ve learned, though, this step isn’t always necessary. If the plant is healthy and if the fleshy roots have not been injured or cut, you can repot immediately: time to remove the old substrate, check that there are no parasites among the roots, and repot in the new substrate. For years I have only allowed plants to dry for a few days in the case the root system has been affected by rot (in this case I also treat it with a powder fungicide) or those plants with major lesions to the primary roots or taproot.

Some examples

In recent weeks, as for years now, I have been dedicating myself to repotting my plants, in particular to repotting some of my sowings from 2017. These are mainly Gymnocalycium (spegazzinii and ferox), Lobivia ferox, Thelocactus lloydii. To these are added some of my sowings of Ferocactus latispinus already of a fair size, since these are plants born in 2010. All the plants are in perfect condition: the roots are healthy and well developed and the plants are robust and well formed. For my convenience and to help the growth of still young plants a little, for repotting I used a standard soil based on pumice, lapillus and peat in equal parts, to which I added 5% of fine sand.

In these photos, here are some steps of the repotting procedures during winter. To learn more about the topic, you can consult the section “Repotting“. If you want to know more about soils and materials for making the various substrates, you can instead consult the “Substrates” section.

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Correlated articles

All articles on sowing cactus and succulents
When to pricking out cactus seedlings
Seasonal care for cactus and succulents
Cactus cultivation cards

L'articolo Repotting cacti in winter: here’s why and what are the advantages of this choice proviene da Il fiore tra le spine.

Based on the experiences of some growers, plants of the genus Ferocactus seem to appreciate the addition of calcareous material in the substrate. Above all, the thorns would benefit from it, which would be significantly strengthened compared to those of specimens grown in more “traditional” soils, for example the classic pumice, lapillus, peat mix in equal parts. Based on this consideration, I wanted to make an experiment with some of my sowings of Ferocactus acanthodes (seeds obtained from a dried fruit taken from an adult plant during a trip to Arizona) and Ferocactus latispinus. The acanthodes were born in 2013, while the latispinus are from 2010. Except for the seedling soil, which was based on peat, pumice and gravel, these plants grew up in the traditional compost with 30% fine peat and the rest pumice and lapillus in equal parts. I generally use this mix when I want to help seedlings develop more quickly, and then pass them into what I consider my “standard potting soil” made of sandy clay, pumice, gravel and 10% peat.

In the following article we see exactly what my experiment consists of, what type of soil I decided to use and above all we see the results with the photos taken two years after the test. (…)

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L'articolo Strengthening the thorns of cacti: a small experiment with some Ferocactus sowings proviene da Il fiore tra le spine.

It’s time for… testing. Between the end of December and the end of February, as soon as I have time, I dedicate myself to repotting the plants in the greenhouse. Obviously I only repot plants in stasis, with very dry soil, postponing the change of pot to spring for the plants that I keep in vegetation in winter, perhaps outdoors (but still in pots and not in the ground, of course). Today I flared and planted about fifty plants that I obtained by sowing in natural light and heat. Some of them were born in 2014, others in 2016 (but already large enough to be repotted). It was an opportunity to start a useful test on various types of soil to understand how this affects the growth of some specific species of cacti.

Let’s see in the following article what exactly this experiment on the substrate consists of and let’s see, thanks to the photographic update two years after repotting, how the plants have grown. (…)

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L'articolo Targeted repotting: sowing identical plants in different soils to test the substrate proviene da Il fiore tra le spine.

Some growers repot every year, while some others repot when required – i.e. when a plant shows signs of suffering or when the pot has become too small related to the stem. There can be many reasons for repotting (or racking, as someone says alternatively) a cactus or a succulent plant, and every grower has his own rules. As for me, I don’t have “fixed deadlines”: I evaluate plant by plant trying to understand if new soil and more space are needed. I repot my succulents when I see that the vase is now too small, when I believe that the soil has exploited or when I want to grow specific specimens more quickly. While it is true that many plants live quietly in the same container for five or six years (in many cases even longer!), it’s also true that frequent repottings (once a year or every two years) help to speed up the growth of cacti, particularly young plants and genera that over time take on considerable sizes, such as Echinocactus and Ferocactus. I repot, also, when I notice that a plant has blocked for a long time and it doesn’t grow or produce new thorns. It can be the spy that something, at the root level, is going wrong. A plant that doesn’t grow or doesn’t swell despite watering, or, again, a plant that loses its colour (showing, for example, a lack of magnesium that not even fertilization can solve) can be saved by a repotting, with the cleaning of roots and the supply of new soil.

So let’s see in this article in which period it is better to repot cactus and succulent plants, which pots to choose (square, round, terracotta or plastic), how to check the roots and how to proceed in practice. (…)

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L'articolo How to repot cactus and succulent plants: in which period, how to proceed, which tricks to use proviene da Il fiore tra le spine.

I may look like a mordant, but I want to clear the field of misunderstandings and false myths: the right soil for cacti does not exist. There are many types of soil (or composts, substrates, mixtures, the question does not change) and there are genera that prefer certain substances and others that require more. Established this and removed one of the first Faq (Frequently Asked Questions) by cacti enthusiasts to the first arms – “Which is the best soil for my cactus?” – it can be said on the contrary that on the one hand there are the characteristics that a good soil for cactus must necessarily have; on the other hand the needs of the single plants. The question was simple and the related answer was given by italian cacti expert Giuseppe Lodi, who, after observing “the butts of roots of certain imports” and having noticed how these were encrusted with clay loam, suggested a base soil absolutely natural and versatile: “You can start from a mixture of common clay loam (field or garden), coarse sand and leaf soil, in equal parts. Of these three components none of them can be enough, alone” (Giuseppe Lodi, “Le mie piante grasse” – Edagricole).

Except perhaps for the difficult availability of the loam of leaves (be careful to go for the woods and get bags of decomposed foliage: there are fines for collections of this kind), the recipe provided by the Italian pioneer in the cultivation of cacti and succulents was more than sensible, as well as experienced. Considering the difficulty of finding the loam of leaves (Lodi suggested leaves of beech or chestnut), that moreover must be well decomposed (and it may contain fungi and bacteria dangerous for the plants), this element can be replaced by good quality peat, sieved fine, without lumps and filaments. Too bad that over the years we have forgotten Lodi advice to focus everything on what for many is still the standard substrate of peat, lapillus and pumice in equal parts, standard enough to fit any kind and species of succulent.

In the following article now we see which is the best substrate for growing cacti and succulent plants based on my experience over the years with proofs and experiments on various mixtures. (…)

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L'articolo Substrate, loam, soil mix: which is the best soil for cactus and succulent plants? proviene da Il fiore tra le spine.