Anyone who has been cultivating succulent plants for a long time – whether they are cacti or other succulents such as Crassula, Euphorbia, etc. – knows well what should be done after transplanting, and he certainly knows that these plants should not be watered immediately at the end of this operation. However, there is repotting and repotting: there is the “invasive” one and the one that involves simply moving a plant from one pot to another. There is repotting which involves total cleaning of the roots and that which involves only a superficial cleaning of the old soil. In short, there are many situations and one can proceed in various ways. However, there are some fixed points and they must be respected if we want to avoid the risk that following this operation the plant will go into stress or, in the worst case, die following a rot that started right from the roots.

This is why this article, certainly useful to the novice, can prove equally useful to the long-term grower. In fact, here we will see the various types of possible repotting, the precautions to use and, above all, what to do (not only from the point of view of watering) once the repotting of a succulent is finished. (…)

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L'articolo Repotting a succulent plant: what to do afterwards and how long to wait before wetting the soil proviene da Il fiore tra le spine.

Those who have been cultivating cacti for some time know it well:  Melocactus  are as fascinating as they are “capricious” and you have to come to terms with it. In this article we deepen the knowledge with this genus, in particular from the point of view of the needs, so as to grow robust specimens and limit losses as much as possible. (…)

Introduction

It is usually said that Melocactus and Discocactus (similar genus in some ways) are plants that are loved and hated at the same time. Yes, because if in fact  Melocactus  have their own undoubted charm, at the same time they are among the most mangy cacti to cultivate. Or rather, all things considered, cultivation is not difficult, the fact is that these plants have a marked “tendency to suicide”: having reached a certain stage (almost always when they have formed the cephalium) they tend to lose their roots and only in rare cases they manage to reform the root system, unlike what happens with most cacti. In summary, it can be said that until Melocactus do not develop the cephalium, they have the same needs as other cacti and are not difficult to grow. Once the cephalium is formed – which is their characteristic element – they become extremely delicate plants,  they cannot bear repotting and do not tolerate low temperatures. All this in cultivation, since these plants abound in nature and manage to be quite long-lived.

Distribution and history

Fundamental, as for all plants, is the knowledge of the area of ​​origin of this genus, knowledge that can provide useful data for the cultivation of these plants. Well, all Melocactus are native to the warm areas of the American continent, in particular south-western Mexico, the Antilles, Cuba, Colombia, Venezuela, Peru, Ecuador and, above all, Brazil. It follows that these are cacti originating from the central belt of the continent, where temperatures are warmer than, for example, those of the American states or northern Mexico. It is precisely for this reason that Melocactus do not tolerate the cold, unlike most other cacti (except for epiphytes).

From a historical point of view, the Melocactus mark a starting point in the story of the study of cacti, since according to many sources, these plants were the first cacti encountered by Europeans during their expeditions to the Americas at the end of the fifteenth century. As far as it turns out, Christopher Columbus himself observed some specimens in the West Indies, precisely in conjunction with his landing on the American continent. It is clear that for Europeans, who did not know cacti in any way since these plants originate exclusively from the Americas, from a botanical point of view that meeting represented an enormous surprise. It is no coincidence that several specimens of these plants were sent to Europe to be subjected to in-depth studies (and it is to be assumed that only a very few specimens torn from their habitat arrived overseas alive and even those few, if equipped with a cephalium, lasted a few months).

If you want to learn more about the distribution of cacti and succulents in the world you can consult this article, complete with maps.

As further confirmation of what is reported by the sources, there would be the fact that the very name attributed to these plants would probably be the origin of the word “cactus”, deriving from the Greek “kaktos“. The latter term had actually been in use for some time to generically indicate thorny plants such as thistle or artichoke and on the occasion of the Melocactus discovery it was decided to keep it, simply by having it preceded by the terms “melon” (i.e. melon) and “ekinos” (i.e. “curly”, or “thorny”). It follows that the first Melocactus were classified as Echinomelocactus, a term later shortened to Melocactus. The first scientific descriptions of this kind date back to several centuries after the discovery, i.e. in the mid-eighteenth century and are by Carlo Linnaeus, botanist and “father” of modern scientific classification. In particular, Linnaeus described 22 species of Melocactus in his famous Species Plantarum, published in 1753. Over the years, many studies followed one another and today this genus has around thirty species in all.

A short description

Regardless of the species, Melocactus are plants with a globular habit, tending to become short-cylindrical with age. The stems are solitary and have no tendency to bunch or shoot, except as a result of trauma. The dimensions of these plants can be defined as medium and range from twenty centimeters in height of M. matanzanus (the smallest and earliest species to form the cephalium) up to one meter in height, without however counting the cephalium, which can reach about thirty centimeters in the oldest specimens. The stems are generally bright green to dark green in colour, but do not lack the bluish tinge typical of the azureus species. The bodies of the plants are divided into very marked ribs capable of thinning or expanding (“accordion”) depending on the quantity of water present in the stem. The spines vary according to the species: they form at regular intervals along the coasts, they are always pointed and never hooked, slightly curved downwards. In some species they can be robust and short, in others thin and up to ten centimeters long (M. ernestii). The color of the thorns is usually white, tending to gray over time (except in some species, where the spine is brown).

The analysis of the root system is interesting, probably this is the real weak point of these plants. The roots of Melocactus are usually underdeveloped, fibrous in the part close to the stem. Here is what George Thomson notes in his volume “Melocactus” published by Cactus&Co Libri (2009): “This means that even modest damage in the first few centimeters of the root can lead to the loss of the entire root“. And this could actually explain why, once the cephalium has formed, it is advisable to avoid repotting these cacti. Thomson observes again: “The roots are very sensitive and the plants lose them easily in case of prolonged periods of drought or in conditions of stagnant water”.

The cephalium

As we have seen, the cephalium represents the element that distinguishes this genus, although over time other genera of cacti also form what is called “false cephalium” (for example the Discocactus). In Melocactus the cephalium represents the watershed that separates the “juvenile” age from the maturity of the plant, i.e. the moment in which the latter is able to flower, produce fruit and therefore reproduce. Before the formation of the cephalium, the Melocactus develop the stem, which almost always takes on a short-cylindrical shape with age. The Melocactus produces offshoots very rarely and generally do so following an arrest in growth caused by a parasitic attack or, in any case, following a trauma sustained during growth, in particular at the vegetative apex. Once the adult stage is reached, after six or seven years in the earliest species (M. matanzanus) or after at least ten years in other species, the stem stops growing and the plant concentrates its energies on the production of the cephalium, which it forms at the apex of the plants and is composed of short, bristly and thick hair, usually red or white. From this moment on, only the cephalium will grow, which in some species reaches 4-5 centimeters (M. bahiensis), and in others it can reach twenty centimeters (M. peruvianus), giving the plant a bizarre appearance. Here is what George Thomson writes about it in the aforementioned “Melocactus – care and cultivation”: “It has been demonstrated that a large part of the stem of a mature Melocactus comprises only juvenile tissue with a transparent epidermis, and the adult tissue, without stomata, is mostly confined to the central nucleus of the cephalium. This juvenile tissue in the stem of melocactus is probably the reason why it is very difficult, though not impossible, to revive a plant that has lost its roots”.

It is from the cephalium that, during the summer, the flowers are formed, which are tiny in size and vary in color from pink to magenta, and subsequently  the fruits, which appear in the form of oblong, smooth, white, pink or red. The growth of the cephalium in height is annual and in some cases it is possible to observe the layers which make evident the annual development of this curious organism. Finally, in some specimens, it is possible to observe the dichotomization of the cephalium, i.e. its division into two distinct parts according to a phenomenon common to other cacti, in which the vegetative apex can divide (dichotomize precisely) and give life to two distinct “heads” (the phenomenon often occurs in Mammillaria parkinsonii, for example).

Cultivation

Fascinating, particular, bizarre but “touchy” plants, Melocactus are certainly not among the simplest cacti in terms of cultivation. Their life and consequently the level of cultivation can be divided into two phases: pre-cephalian and post-cephalian. Before the formation of the cephalium  the Melocactus can be treated exactly like most cacti and  also tolerate minimum winter temperatures close to zero Celsius degrees. Once the cephalium has formed, cultivation becomes more demanding: the plants no longer tolerate repotting, unless you simply remove the plant from the old container to gently insert it into a new pot without touching the roots (even in these cases, however, some specimens can go into stress and stop growth). Furthermore, since the plant has reached the adult stage, it is advisable  to avoid the winter cold and the Melocactus, from mid-October to the end of April, must be placed in environments sheltered from the rain and where the minimum temperatures do not drop below 15-16 degrees. They can also be placed in the apartment, in a bright place, but they must be watered in moderation no more than once a month and only to prevent the root system from drying out completely. If the stem does not show signs of suffering (in other words if it remains swollen and turgid) it is also possible to limit winter watering to once every two months, so as to further reduce the risk of collar rot.

As far as the substrate is concerned, whether the plant is still young or has a cephalium, the situation does not change and  the Melocactus need very draining and light soils. You can use the tested mix based on peat, pumice and lapilli in equal parts (possibly reducing the peat part and increasing the pumice or adding river gravel or quartzite), or you can create a substrate starting from common clay (a maximum of 20%) by adding a little sand, a little peat (10%) and for the remainder various inert materials such as pumice, gravel or quartzite.

No particular indications regarding  watering and fertilization: during the growing season, Melocactus (with or without cephalium) must be treated like most cacti, with regular watering every two weeks and three or four fertilizations at most. Finally, as far as exposure is concerned, these plants need a lot of light but not necessarily direct sun, which can burn or discolor the epidermis since the thorns are thick enough to protect it from the intense rays of the sun in July and August, especially between noon and 3 pm. A shaded greenhouse, a windowsill, a balcony or a terrace facing Southeast will be ideal and if the direct sun hits the plants throughout the day, it will be sufficient to place the Melocactus in the shelter of shrubs or large plants.

Sowing

The sowing of these cacti is simple and also suitable for those who intend to practice. The fruits are produced autonomously by the plants and emerge from the cephalium during the summer. It is sufficient to extract them by gently pulling the “petiole” formed after the flower has dried, but be careful: it is advisable to wait until the plant has expelled the fruit for at least half of its length. The berry must be able to slip off without any effort; otherwise it should be left in place because tearing the fruit would put the plant at risk, which would end up with a broken and moist berry inside the cephalium (actually, a gateway for pathogens and bacteria). Once the berries have been removed, they are left to dry for a few weeks, then they are opened and the round, black and small seeds are extracted. The sowing procedure is the same that we adopt for almost all cacti (the seeds do not require any  treatment) and growth during the first few years is not particularly slow. With the matanzanus species, for example, 7-8 years are “sufficient” to obtain plants with cephalium.

Main problems

Overall, Melocactus are quite robust plants and if well cultivated they are not subject to adversity in a different way than other cacti. They are certainly  particularly sensitive to water stagnation, especially in winter, therefore it is advisable, with these plants, to always have a light hand when it comes to watering. A phenomenon that frequently affects Melocactus (and which can happen with any cacti, albeit less frequently) is the loss of the root system. Often, even without apparent causes, in the absence of parasites and without having repotted, the roots of Melocactus go into “tilt”. It almost always happens with specimens equipped with cephalium and when we realize it, it’s too late to intervene: the stem dehydrates, deflates and despite watering it does not regain volume. The problem is that a plant with a cephalium seems almost incapable of reforming its root system. In other words, no matter how much care we give to the specimen (flaring it, cleaning the roots, removing the dry ones, placing the plant on pumice), the touchy Melocactus always seems to prefer a slow agony rather than reforming the roots and starting again, as does the most cacti. The sad consequence is that the specimen can remain alive even for two or more years, until the water reserves accumulated inside the stem are completely consumed…

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Growing with Seramis

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L'articolo How to cultivate Melocactus, cacti that with age put on… the hat (“cephalium”)! 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.

Hydroculture and succulent plants sound, in some ways, like a conceptual oxymoron. Plants that have naturally evolved to cope with drought, rainfall concentrated in short periods of the year; plants that grow in extremely dry soils, in short, how can they get along with hydroculture? In other words, how can they be grown with a technique that requires the roots to be in constant contact with water? The answer is simple: they can’t. However … however in certain cases and following precise precautions, the constant contact of the roots of a succulent plant with water can be used to save that plant. Even if that plant is a succulent. And that’s exactly what I’m trying to do these days to save two Astrophytum asterias of my sowing in conditions of extreme dehydration, on the verge of dying of thirst (which would be very strange for a cacti!). But let’s go step by step and see exactly what happened to these two plants and how (and why) I’m trying to save them through a kind of “temporary hydroculture”.

I explain everything with lots of photos in the following article, which I consider – in fact – the description of an experiment that is perhaps risky and certainly unorthodox but at the same time not devoid of logic. (…)

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L'articolo Severely dehydrated Astrophytum asterias: here’s a rescue attempt with… hydroculture! proviene da Il fiore tra le spine.

Net of purely aesthetic and therefore personal choices, let’s see how to choose the right containers for succulents’ cultivation, evaluating the pros and cons of the various shapes and materials with which the pots available on the market are made. (…)

Foreword

Cacti and succulents, in general, are very tolerant and adapt to various methods of cultivation. This is another reason why the choice of the pot is often dictated almost exclusively by aesthetic reasons. Over the years, I have seen cacti grown in enamelled pots, in bonsai pots, or in tin pots, if not in recycled cans, or even in elegant wooden containers. The aesthetic aspect is not up for discussion: it is personal and gives little or nothing to “reason”, that is, the pros and cons of cultivation. In short, in these cases, the pot is chosen because it is liked. This is not the idea of cultivation I’ve had through the years, as those who follow this site know, based on the plant’s wellbeing and on obtaining robust specimens that look as much as possible like those plants in nature. For myself, concerning the use of pot or container, the aesthetic aspect is definitely in the background. I’m not saying that I don’t appreciate a beautiful setting in an aesthetically pleasing vessel (I’ve made more than one myself over the years): I’m just saying that for the vast majority of my plants, the choice of the pot is dictated first and foremost by “functional” reasons and in this area, as we will see later, countless considerations have to be made, pros and cons to be weighed case by case.

Vases, bowls, cassettes: the types

Beyond the compositions, which bring together several plants in a single container – often neglecting that plants have very different cultivation needs – succulent and cacti can be grown in single pots or in large containers, such as bowls or crates, capable of accommodating a variable number of specimens. The pros of the choice of the single vessel are obviously the saving of space, the simplification obtained in the management of a single container (even if heavy) compared to the moving of many little pots and in fact that in single pots, the plants have more space to expand their roots and, consequently, more soil. The cons of this choice, however, are significant. Firstly, some plants will colonize the space faster, spreading their roots at the expense of others, with the result that the latter will grow more slowly and remain smaller. Secondly – and in my opinion, this is the most important consideration – in case of disease, we risk losing all the specimens and not only the one initially affected. Let’s think of a cochineal attack, for example: in plants in close contact, the parasite will soon pass from one specimen to another. Worse still in case of root parasites or fungal diseases, in particular, those originating from bacteria present in the soil: in these cases, the affected plant will quickly share the problem with all the others grown in the same container, and we risk losing not one but all the plants grown together.

Another risk for that plants grown in single containers is related to watering. If we water at the wrong time or exceed it (especially if the soil is not correct), we’ll have water stagnation that will affect all. Because of this, I have been growing my plants in single pots, limiting the cultivation of multiple specimens in single boxes or bowls only to some succulents such as Lithops, Crassula, Sempervivum and Echeveria, or particularly strong cacti such as Echinopsis. I also grow my seedlings in single containers for obvious reasons: I place several seeds in the same vessel, and for one or two years after germination, the seedlings remain in that same container. When I have to replant the seedlings, I consider the size of the single specimen. I put plants of two or three centimetres in single pots, while smaller ones will share boxes, seed pots or Styrofoam containers, well-spaced between them to allow the correct root development. In some cases, it has happened to me to lose some single specimens of my sowings because of rottenness, but fortunately, I have never had collective deaths, not even in all those cases in which I have limited myself to remove the rotten specimen without removing the others grown in the same container.

Plastic, brick, aluminium: the materials

On paper, we could say that by now, we are spoilt for choice, as we can easily find pots in plastic, terracotta, aluminium, wood, stoneware, glass, glazed terracotta and other materials. If time ago terracotta was considered the best, today the possibilities are really endless, also considering… the creativity, which can lead to making vases with recycled objects, such as milk, cans, containers of various shapes and sizes…

 Plastic  – While it is true that every material has its merits and demerits, as far as I am concerned, plastic and terracotta remain the two most viable alternatives. Having thousands of plants over the years, I have definitely switched to plastic (although from an environmental point of view, it is not the best…). The reasons that can lead to prefer plastic pots, which are easy to wash and recycle, are many: first of all, the weight, which is decidedly low compared to one of the terracotta pots. This may seem a minor consideration, but when you have many plants to move twice a year from the greenhouse to the outside (and vice versa), your back will tell you that there is no match between plastic and terracotta.

Another characteristic of plastic is that it does not allow any transpiration from the inside to the outside. In other words, the walls of plastic pots, differently from the terracotta pots, do not allow any air exchange between the substrate and the outside. This cause that water to take longer to evaporate, as it can only evaporate up to the surface. So we will have to learn to calibrate the watering according to the pot size (a 2-inch pot contains very little soil compared to a 10-inch pot, for example) and, above all, according to the substrate composition. Of course, the bulk of the work will be done by the plant itself (in addition to the drainage holes in the bottom, which are necessary for any pot), which absorbs water from the substrate, contributing significantly to the substrate drying quickly. And this brings us to the advantage of plastic over terracotta: by retaining moisture longer with plastic pots, we can water at longer intervals. When you have many plants, this is a “detail” that loses the connotation of “detail” to gain value.

 Terracotta  – Terracotta pots are undoubtedly more environmentally friendly, more pleasing and natural to the eye and retain (at least in my eyes) an undeniable retro charm. It’s reasonable to opt for terracotta if you have a few plants, and you don’t need to move them several times during the year. However, you have to consider that terracotta allows transpiration from the pot’s inside to the outside, with the consequence that the soil will dry more quickly. While this at first glance may seem like an advantage, in the warmer months, the substrate if very draining, and it will dry out so fast that close watering will be necessary (in summer, even every other day). As long as you have only a few plants, this is not a problem, but when we start to get the hang of it, and the specimens exceed a hundred, watering them all every other day becomes almost another day job: try it!

The third disadvantage of using plastic is generally discovered during the first repotting, especially when you do it after some years. Thanks to the porosity of terracotta, in fact, the roots of the plants, once the colonization of the soil is over, literally cling to the inner edges, so they can take advantage of the humidity that permeates the pots themselves. Over time, the capillary roots cover the pot’s inner rim, forming a sort of “felt” that glues the plant to the vase. When repotting, nine times out of ten, after sweating (and probably swearing) for an interminable amount of time, you will find that the only way to get the plant out of the pot is to take a hammer and crumble the terracotta. At that point, you’ll have more tears to shed: some for the vase itself, which you’ll no longer be able to use, and others for the work ahead of you to break up the loaf of soil and free the felted roots, compact and tangled like the plot of a psychological thriller.

With plastic pots, to flare the plant, most of the time is sufficient to turn the pot upside down, or, in case of large or particularly thorny plants, wrap the plant with a cloth and pull it out of the pot. The only difficulty, when repotting succulents in plastic pots, I found when I let several years pass since the previous repotting: in those cases, the plant had fully colonized the soil, deforming the vase under the pressure of the roots and making it almost impossible to extract, to the point that I could only cut it with a cutter.
Terracotta pots, as plastic pots, are also easily recycled and can be washed, although it takes longer due to the material porosity.

 Aluminium, glass, wood  – With other non-transpiring materials, such as glass and aluminium, the same considerations listed for plastic and related to non-transpiration of soil are valid. However, we have to add the defect that characterizes terracotta, the pot’s weight (at least if we have vases with hard size). Since aluminium and glass containers are generally made for purposes other than plant cultivation, or at best are used as pot covers, it is essential to make sure that drainage holes are present at the bottom: never use pots closed at the bottom (and this applies not only to succulents but to any plant). Wooden pots and containers can be very aesthetically pleasing, but unless they are covered with a plastic sheet inside or treated with special paints, they are destined to become impregnated with water and, over time, to deteriorate and rot, especially in case of outdoor or greenhouse cultivation, with a sprinkling of water.

 Enameled pots for bonsai  – Evergreen pots for bonsai have always been very appreciated and used by cacti and succulents growers. From an aesthetic point of view, they can be real works of art, but from a functional one, suitable for growing succulents only in some cases. This is mainly due to their shape, generally box-shaped and therefore wide and low, so not very compatible with the expansion of the roots in-depth and not recommended for plants with taproots, such as Ariocarpus, Lophophora, certain Coryphantha, certain Mammillaria and many other cacti. Moreover, unless the inside is enamelled, it’s better to avoid bonsai pots in the cultivation of succulent plants: if we leave the plant for too many years in the same container, the only way to take it out will be to break the pot. A real shame, considering the aesthetic and economic value of this type of vases.

Round or square, high or low?

Regarding the shape of the pot, there is little to discuss on a functional level: here, it’s more a matter of taste because the plants adapt perfectly to any type of container, be it round or circular. Generally speaking, it can be said that shallow and wide bowls are better suited to accommodate globular or tall cacti, while traditional cone-shaped or cylindrical pots are aesthetically more suitable for columnar succulents.

One factor that can play a significant role in the option when you have many plants is undoubtedly space-saving. In this case, the square pot is the first choice: it has been specially designed to ensure the full use of space by the plant and, with the same size as a round pot, the square pot contains more soil. And that’s not all: if placed side by side, square vases avoid considerable waste of space compared to circular vases, which, even when placed side by side, will not allow to fully exploit benches or shelves, leaving triangles of empty space between one edge and the other. If with few plants, this consideration can have a relative weight, with hundreds or thousands of specimens, the choice becomes almost compulsory, unless you have a considerable number of huge greenhouses. It is no coincidence that square pots are the ones most used by collectors and specialized nurserymen. Whether you opt for the square pot or the round one, there are two elements to consider when repotting the plant. The first one is the steam size, the second one is the size of the root system. In both cases, there must be a proportion between the plant and the container. As for the stem, the choice is simple and entrusted to aesthetic canons, keeping in mind that it is appropriate that the pot can easily contain the body of the plant and, possibly, the thorns (unless these are exceptionally long, as in the case of some Lobivia or some Ferocactus). As a general rule, it’s recommended there can be two to four or five centimetres between the stem and the pot’s edge.

However, concerning the root system, the evaluation requires some experience and a surplus of observation when we’ll have flared the plant. First of all, if we are dealing with a cactus with a taproot (i.e. a “carrot” root, as in Ariocarpus), it’s necessary to use high pots, where the taproot can be comfortably accommodated, and the rootlets can develop in-depth rather than width. In these cases, we will avoid bowls and choose cylindrical or square pots instead (in the last years, you can find high pots for plants like Ariocarpus, Lophophora, etc.). If, on the other hand, the root system is not taprooted, we will have to evaluate based on the specimen to be repotted: if the roots are short and thick or if we see that they tend to develop horizontally (this is the case of Echinocactus and many Ferocactus, for example), we can use low and wide bowls or square pots that are not too deep (with the same length of the side, there are high square pots and low and squat square pots). 

One thing, based on my experience, I can affirm: cacti and succulents, contrary to what has been believed for years (and contrary to what too many enthusiasts still believe), do not fear large spaces in which to grow. Miniature pots are an imposition and only limit the growth of the plant. On the contrary, if the soil is balanced and draining, ample and deep pots favour the correct plant’s development of the plant without exposing it to the risk of water stagnation that can trigger rottenness.

It is a different matter if the plant is suffering and the root system is compromised or absent because, in these cases, the choice will fall on low pots and bowls, which we will fill with pumice for helping the plant emit new roots. Large pots can be inadequate if the roots are missing or suffering, because they contain an excessive quantity of soil which not absorb the watering and will remain too long in a wet substrate, if not soggy. So initially, it’s better to use pots and bowls that are not bigger than the ones of the stem, postponing to a second time – at least a couple of years later when we are sure the plant will be healthy again – the repotting in a container suitable for the size of the specimen and for the new root system.

Cactus without roots: how to intervene to save the plant and make it healthy again.

Colours and particularities of pots

From a functional point of view, the importance of the pot’s colour is not so relevant. Some say that black pots can be dangerous because, by attracting and keeping more sun rays, they could favour the substrate overheat and causing the roots to suffer. Theoretically, the argument is not out of place, but for over twenty-five years, I have been using black pots (the classic square pots for growing), and I have never had problems due to overheating of the roots, even in plants that I keep outside the greenhouse, exposed to direct sunlight. In short, I have never experienced any difference from the plants I grow in terracotta-coloured plastic pots, even when, in the middle of summer and after hours of direct sun, they are hot.

I know growers who have the patience to cover the outside of their pots with white tape, just as I know a brilliant grower, David Rubbo, who has the patience to “insulate” many of his pots. He cuts out some polystyrene’s sheets less than a centimetre thick and puts them in square pots inside which he then places the vases in which he has set his plants, thus creating a sort of internal insulation able to lower the incidence of sunlight on the walls of the pot.

Among the peculiarities of the pots currently on the market, it is worth mentioning the anti-spiralization grooves. These are small canals that run along the edges of square vases so that the roots avoid, over time, to turn around the inner walls of the vase, creating tangles that are difficult to untangle when repotting. Frankly, I have never had the chance to experience its usefulness, and when, during repotting, I have to deal with tangled roots, I arm myself with patience and try to free them as much as possible. Apart from the colour, the shape or the anti-spiralization channels, only one thing must never be missing in pots: the drainage hole or holes. Essential for all plants, they are even more so for succulent plants, which do not tolerate water stagnation or excessive humidity. In old terracotta pots, there is always a single drainage hole at the bottom. It’s wide enough to avoid excessive spills of soil, it can be covered with a stone or with a shard of another pot, and it is more than enough for the purpose.

In plastic pots, especially in the square ones, there are usually more slits on the bottom to allow excess water to drain without the potting soil leaking out during repotting when it is dry and not yet settled. On the market, finally, you can also find pots with a semi-open bottom, that is, with a simple radius: in this way, the outflow of excess water is maximum, but it will be necessary, during repotting, to put coarse material on the bottom (lapillus or expanded clay) to prevent the soil from leaking out immediately.

How to choose the pot: the criteria

In the light of the elements just described, choosing the right pot wherever to place a cactus or a succulent plant might seem a difficult task. Actually, all you need is a little experience and knowledge of your cultivation method and of the conditions that you will be able to ensure to your plants: for example, air, full light, minimum temperatures, frequency of watering and fertilizing, type of substrate. The rest is just a compromise between one’s aesthetic taste and the functional aspect. It’s essential to respect the plant’s root system structure and ensure sufficient space for the specimen’s development and growth. You don’t need “bathtubs”, but you should avoid the tiny pots (under 5 centimetres) in which we almost always find succulents in non-specialized gardens. The correct potting soil and the right cultivation will do the rest.

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Correlated articles

Six identical cacti in three different soils
How to repot cacti and succulent plants
Substrates for cacti and succulents
The correct soil: the materials you can use

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L'articolo Plastic, terracotta, square or round? Here’s how to choose pots for cacti and succulents 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
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L'articolo Repotting cacti in winter: here’s why and what are the advantages of this choice proviene da Il fiore tra le spine.

Succulent plants, and cacti in particular, have evolved to accumulate water reserves and thus be able to deal with long periods of drought. In their natural habitats, cacti are subject to sudden changes in temperature between night and day, but also to an alternation between periods of total drought and periods of great water availability. In the sub-desert regions of the southern United States (California, Arizona, Texas, Nevada, etc.), as well as in Mexico, Central America and Latin America (Chile and Argentina, for example), during the growing season, corresponding to spring and summer, the hot, dry days are often abruptly interrupted by heavy downpours. If in nature the plants know how to manage these conditions without particular problems, in cultivation it can happen that the transition from the stasis season to the growth season, if accompanied by an overly “decisive” resumption of irrigation, gives rise to the phenomenon of splitting of the stems.

In this article we see how and why this phenomenon can occur, how to remedy it to prevent the plant from contracting rot and above all how to avoid splits. (…)

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L'articolo When the cactus “explodes” from too much water: how to avoid cracks on the stem proviene da Il fiore tra le spine.

Cacti can be capricious plants, expecially because of their roots. It can happen, in fact, that despite all the cares we dedicate to one of our succulent plants, it stops growing, stops producing thorns and flowers and, in the space of a few weeks (or months, in some cases), begins to deteriorate, deflating and turning yellow. At the origin of this phenomenon, not always a pathology exists, as a bacterial attack that can cause the rot. In the same way, the cause may not necessarily be due to a parasitic attack. If you look closely at the plant, for example, you might not find any traces of spider mite or mealybug, the two main pests of succulents. With experience I have learned that when a plant, even apparently healthy (i.e. not affected by parasites or bacteria) and grown in the best conditions (light, air, watering, soil, etc..) begins to deteriorate deflating and yellowing despite watering, it is always better to remove it from the pot and check the health of the root system. More often than we might think, the problem can hide just there, below the collar.

In this article we will see everything we can do to save a cactus or a succulent plant in evident difficulty or when, after having flared it, we realize that it has lost all or part of its roots. (…)

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L'articolo Cactus without roots: how to save the plant and which soil to use to get it back to full health proviene da Il fiore tra le spine.

Let’s see how to proceed and all there is to know about repotting,
especially the most challenging ones due to the plant’s size and the thorns on the stem. (…)

There is repotting and repotting…

Obviously, repotting is easy for Cactaceae or succulent plants with little or no thorns, such as most Astrophytum, but also Matucana madisoniorum, many Gymnocalycium, some Turbinicarpus, Frailea, as well as plants with papery thorns (Tephrocactus articulatus v. papyracanthus) or silky-thorns, such as some Mammillaria and Rebutia, or succulents such as Echeveria, Crassula, Lithops, etc… In the same way, everything is easier if you are dealing with young specimens and therefore of small dimensions. In these cases, even the most prickly plants can be repotted without problems since the plant itself weighs very little, and it is not necessary to exert pressure or special efforts to remove it from the pot and place it in a new container.

Challenging repotting

For more demanding subjects, such as a E. grusonii from 20 centimetres in diameter upwards, it is necessary to be patient and take some precautions. Many people use gardening gloves: I avoid them because they deprive the hands of the slightest sensitivity, and it is easy to break thorns or damage the plant if you don’t have the right… touch. When starting a repot of this kind, i.e. large plants covered in thorns, the first thing to do is to have the necessary supplies on hand, i.e. the new pot and the potting soil. At that point, it will be enough to wrap the plant in an old towel or fix some polystyrene blocks to the thorns to protect them and avoid breaking them or getting pricked. When the plant is “packed”, it can be lifted and tilted to the side so that the old pot can be removed.

If the plant has been in the old container for many years and the soil is compact, the operation could be more complex. In the case of a plastic pot, you will have to vigorously beat the walls of the container with the palm of your hands (in many cases, you need your fist!) to try to make the soil loaf come off and slide the plant out. If you have used a terracotta pot and the plant has not been repotted for years, you may need to arm yourself with a hammer to break the old container. With terracotta pots (porous material, unlike plastic, which is perfectly smooth), the roots stick to the inner walls because they can absorb water, and in many cases, during the repotting, there’s no alternative to breaking the old container.

In this regard, it must be said that even the choice of the correct pot is fundamental, and on every type of container, there are pros and cons. Terracotta or plastic? Round pots or square pots? Small vases or wide bowls? Many individual vases or more plants in one container? All of these questions are answered, as well as fully explored, in this article.

On repotting, in general, you can find everything at this other link.

Once the plant has been freed from the old pot, it is advisable to check the state of the roots, verify that there are no parasites such as cochineal and remove as much as possible the old soil. If the plant is already in suitable potting soil, it will be enough to shake it and free the roots a bit; if the old substrate is rich in peat or too much used, it’s better to get busy (maybe even with the help of a brush) to remove it and free the root system.

If some roots are too long, and if they’re not primary roots (thick and fleshy), you can shorten them with scissors or gardening nippers: just a clean-cut, the plant has no problems, stimulated to produce new capillaries.

New pot, new soil

Before repotting, many people recommend leaving the plant’s roots in the air for a few days to allow them to heal the wounds suffered during cleaning. Frankly, I see the reason only if some primary ones are broken, or the root system has been thoroughly cleaned, for example, because the roots were dry or rotten. In other cases, I repot immediately after cleaning, with the only care to use dry soil and not to water for at least ten days after repotting.

Whichever choice you made (wait a few days or repot immediately), all you need to do is to put a little potting soil in the new pot, place the plant on it, being sure the collar is at the right height related to the edge of the container and fill it all around the stem with the new substrate. Some growers recommend putting expanded clay, pumice, or coarse-grained lapilli in the bottom of the pot to promote drainage. I do this only when I use very profound vases compared to the size of the root system or when the roots are few, dry or too short: in all other cases, I see no reason to deprive the plant of soil if it’s already draining and rightly formulated.

Here I have written about the various types of substrate I use.

With small plants, easy to handle, it is better still to hold the plant with one hand, place it at the right height related to the edge of the pot, leaving the roots in mid-air, and fill the pot with potting soil with the help of a shovel. At the end of this operation, it is a good idea to lightly tap the edges of the new container with your hands, then lift and drop the pot several times on the table to let the potting soil settle and not leave empty areas inside the container.

A little trick

More than strongly thorny plants – Ferocactus, for example, can be easily handled by lifting them by the old thorns, as they are so strong – in my opinion, the real problem is plants with fragile or hooked thorns. In the first case, you need a lot of attention and a good dose of experience (and patience) to avoid breaking the thorns; in the second case, you need a lot of attention because the hooked thorns (as in the genus Ancistrocactus) will inevitably get stuck to the skin with the risk of making it difficult to clean or move the plant while filling the new pot with soil. A trick with this type of plant is to flush and clean the plant, place two sticks (or two brushes that are not too large) on either side of the new pot, place the plant between the two sticks, holding it by the spines and letting the roots fall free into it. When the plant rests on the two supports, we will have our hands free to fill the pot with soil, and when we arrive at the right level, we just have to take out the sticks, hold the plant by the thorns and finish the job by putting the substrate around the collar.

Beware of glochids!

The really tricky plants are those of the Opuntia genus. Most of them have very short and thin thorns, called glochids, that can enter the skin and firmly hook thanks to the hooked tip. Glochids don’t hurt, but they are very annoying, irritating and almost impossible to remove immediately. For repotting these plants is the only time I use gloves unless the Opuntia “blades” are large and the glochids are widely spaced, in which case you can handle the plant without getting glochids on your fingers.

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Correlated articles

Six identical cacti in three different soils
How to repot cacti and succulent plants
Substrates for cacti and succulents
The correct soil: the materials you can use

© 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 Repotting cacti: a few tips on how best to do it without… donating blood! proviene da Il fiore tra le spine.