With the beginning of autumn almost all succulent and cacti begin to prepare for the vegetative stasis which will last until February/March. In the winter months, cacti (with some exceptions such as Melocactus, Discocactus and epiphytes such as Epiphyllum) and many succulents (with the exception of those originating from the southern hemisphere or areas such as Madagascar) stop growth and go dormant to recover energies and be able to flourish during the following season. In these months the plants should be kept cold and should not be watered. However, it is useful to carry out some preventive treatments to prevent the formation of mold or fungi during these months, thanks to the winter humidity, which, when the temperature start to rise, triggers rot. Warning: preventive treatments with chemical products can be useful but do not necessarily have to be carried out. It is simply a preventive measure, since the best form of defense is always the spartan cultivation of plants accompanied by a good exchange of air during autumn and winter. There are growers who limit these treatments to the essentials, perhaps favoring products with a low environmental impact (I myself have adopted this decision for years) and growers who abuse chemical products in the hope of thus making their plants invulnerable to animal parasites, fungi and mold.

In this article, which completes what has already been explained in other articles (which you will find thanks to the internal links) we see what is advisable to do in these weeks to protect the plants and limit losses due to rot or parasites as much as possible. (…)

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L'articolo Here comes autumn: what treatments can we do to protect succulents and reduce losses? proviene da Il fiore tra le spine.

Now let’s see everything we can do at this time of the year, especially if we don’t have a greenhouse and we grow on the windowsill, on the balcony, on a terrace or in the garden. With a warning: whatever you have to do, with succulents and cacti, you must not be in a hurry: hurry to water, hurry to treat, hurry to move the plants… Getting caught up in the rush, the anxiety, the fear of doing something wrong, is the best way to run into mistakes. So let’s see how to avoid them. (…)

Check the plants

The first fundamental action in spring is to check the plant carefully for detecting any traces of bacterial diseases (dark spots caused by fungi) or parasites (particularly the mealybug/cochineal). In the first half of mid-March, even with healthy plants, it’s however advisable to carry out some preventive treatment by spraying stems and leaves with a specific pesticide (against mealybug and spider mite) and, about ten days later, with a broad-spectrum fungicide (attention: copper oxychloride should be used only when the plants are in stasis, so from March should be suspended). Both treatments – pesticide and antibacterial – must be repeated a fortnight after to ensure complete coverage of the plants.

Give as much air as possible

When the minimum temperatures have settled at 10/12 degrees, it’s essential to give succulents as much air as possible. Plants that have overwintered indoors (except for some species, a thing to avoid!) or in cold but closed environments such as a basement, a garage or a veranda should be moved outdoors and placed on windowsills, terraces, balconies. If plants have been overwintered outdoors, protected by sheets or layers of non-woven fabric, they should simply be uncovered so they can benefit from all the possible air. In these cases, it’s necessary to pay attention to the weather because prolonged rains in a period characterized by not yet high temperatures can be dangerous for succulents, which do not tolerate water stagnation in the soil and excessive humidity. The plants must be placed on a balcony or terrace protected from the rain or covered by a roof.

The sudden changes in temperature that characterize spring, with daytime highs above twenty degrees and nighttime lows that can drop sharply below ten degrees, should not worry: in nature, almost all succulents are exposed to similar conditions and indeed greatly benefit in terms of growth and flowering. Exceptions are succulents coming from areas close to the Equator, such as those from Madagascar (Adenium obesa, but also Uncarina, Alluaudia and Pachypodium) or some cacti coming from tropical regions of South America, such as Melocactus, Discocactus, Epiphyllum, Schlumbergera, Rhipsalis: these species need minimum temperatures not lower than 15-16 degrees and to be moved outside only later, in late spring.

Air is of fundamental importance for any plant, even more so for succulents, which do not tolerate environmental humidity nor water stagnation in the substrate. In open-air, the soil dries faster, the stems can transpire effectively, and the risk of bacterial attack is significantly lowered. Tight, closed environments without air exchange are to be avoided, especially in spring and summer, when succulents are in full vegetation, and their tissues are swollen with the water that constitutes their water reserve, and it is, therefore, necessary that the soil dries quickly after the plant has absorbed the liquids it needs.

Exposure: getting plants used to it

Closely related to air is exposure to the sun. In spring (in march), it’s necessary to provide succulents with more light to encourage proper development of tissues, leaves and thorns and at the same time encourage flowering. Be careful, though: as with all plants, succulents (including Cactaceae) need to be grown gradually. Moving a plant that has spent the winter indoors outdoors and immediately placing it in full sun can be dangerous even for the most “fierce” and thorny cactus, which will suffer sunburn and stem discolouration. We will have to gradually accustom the succulents to the light, which becomes more and more intense in spring, exposing them to direct sun a little at a time. From the middle of March, it will be sufficient to place succulents on a windowsill exposed to the South or Southeast (exposure to the North is to be avoided because it does not provide enough light), or on a balcony, a terrace or directly in the garden, taking care, however, to place them in the shade of outdoor plants that will act as a screen to sunlight. Alternatively, it is possible to protect succulents with a simple gardening net or with a piece of mosquito net properly fixed to braces or supports and able to screen at least 30-40% of sun rays.

In the shade of other plants or screened by shade netting, succulents will gradually get used to direct sunlight, and within a month to a month and a half, you can bring them to the foreground or remove the shade netting. As far as exposure is concerned, it’s still important to know the needs of our succulents since there are genera that tolerate intense sun and others that prefer a little shade (like many species of Euphorbia or Haworthia, for example). When in doubt, it is good to provide succulents with bright light all day long, exposing them to direct sun rays only during the morning, not later than midday. In this way, it’s possible to avoid sunburns and to guarantee the necessary light for the best growth. Particularly for cacti, which will continue producing “important” and not stunted thorns and at the same time keep compact and harmonious stems. When we have a better knowledge of our plants and have learned their needs, we can be more “targeted” when they come to exposure and give the various specimens the right amount of direct sun (for example, in the case of almost all cacti).

To learn how to distinguish succulent plants and know their needs, you can read this article dedicated to classification.

Resume watering

As the exposure to light, which should be gradual, watering should be increased little by little. During the winter, watering should be suspended for almost all succulents, while in spring it’s necessary to accompany the resumption with initially moderate and then more sustained watering. As spring approcaches, in March (weather permitting) a couple of waterings will be enough, while in April, it will be possible to go up to one watering every ten days, making sure to wet well all the soil. From May, you can further increase the watering, reaching one per week. Be sure that between one watering and the other, the loam can dry completely. As always, the advice with succulents is not to overdo it: it’s easier for a succulent plant to die from too much water than from thirst. Consider that these plants are xerophytes, evolved to deal with long periods of drought: when in doubt, it’s a good idea to postpone watering. For regulating the frequency of watering, it’s fundamental also the composition of the soil: here, you will find the “recipes” of various substrates that I have tested over the years.

Fertilize: which products to use

With the arrival of spring and the increase in watering, it’s beneficial to fertilize (or “manure”) succulent plants to promote balanced growth and encourage flowering. As for any other plant, fertilizing is essential to replenish the soil with nutrients that are lost. However, you have to use a specific fertilizer for succulents and not rely on universal products or, worse, calibrated for other plants, such as orchids or horticultural. Wrong fertilization, both in terms of the type of product and frequency, can cause severe damage to the plant and compromise its growth, arriving, paradoxically, to weaken it, as well as deform the stem. Therefore, it’s necessary to limit fertilization (I am very stingy in this regard: two or three fertilizations per year, at most), to be administered by simple watering diluting the product in water, to a maximum of once a month from April until mid-June at the latest, with a further pass in September, before the plants slow down the vegetation.

As for the product, on the market, there are specific fertilizers for succulent plants, and generally, high-quality products have correct ratios between the various macroelements. Knowing how to interpret the label, however, is the first step. Basically, it is sufficient to verify that the level of Nitrogen (indicated with the initials “N”) is considerably lower than that of the other two macro-elements that make up all fertilizers for plants, namely Phosphorus (indicated with the letter “P”) and Potassium (“K”). As an indication, a good fertilizer for cacti and succulents should have 1 part Nitrogen, 2 or 3 parts Phosphorus and 4 or 6 parts Potassium. The dosages indicated by the various manufacturers are variable, but it will be enough to keep these proportions in mind to choose the correct product. According to the most commonly used formulations, we can have a ratio of 6-18-36, or 5-15-30, where 5 stands for the Nitrogen dosage, 15 for the Phosphorus one and 30 for the Potassium one. Balanced fertilizers are to be avoided, those with equivalent dosages of the three macroelements (for example, 10-10-10). In addition to the three macroelements, a good fertilizer for succulents should not lack the so-called mesoelements and microelements, such as calcium, magnesium, sulfur, manganese, boron, copper, zinc, iron, which contribute to a balanced development of the plant in various aspects: root system, stems, thorns, flowering, disease resistance.

For the dosage, it will be sufficient to refer to the indications on the package, taking care to halve the quantities in order not to overdo the fertilization, since succulents are extremely adaptable plants with few needs in terms of nutrients, many of which are already present in the growing medium.

If you want to learn more about fertilization, you can read this specific article.

Don’t be in a hurry

In closing, by my experience and the constant contacts I have with readers and enthusiasts who ask me for advice, I would like to reiterate the concept expressed at the beginning of this article: with cacti and succulents, don’t be in a hurry, never anxious. Our plants are more robust and tolerant than we think: let’s make their time our own and not let ourselves be led by the frenzy of wanting to give them excessive attention. Let’s limit ourselves to the correct care and respect their times, which are decidedly less hectic and anxious than ours, remembering that the border between passion and obsession can be thin…

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Here is a video of me moving some of my plants outside my greenhouse:

Correlated articles

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 Preparing cacti and succulents for spring: exposure, fertilizing, here’s what to do proviene da Il fiore tra le spine.

Circumscribed dark spots, yellowish spots, dryness, discoloration of the stems, reddening, small cuts: over time, signs of various kinds and of varying size may appear on the stem of our cacti. In some cases there is nothing to worry about, because they are small wounds caused for example by the thorns of a nearby plant, or because they are simply the signs resulting from the aging of the plant. In other cases, however, it is necessary to intervene immediately, because that spot is perhaps due to some fungal pathology destined to expand until it seriously disfigures or kills the plant. But how to distinguish a harmless thorn prick scar, for example, from dangerous rot? How to understand if that discoloration of the stem is caused by the sudden exposure of the plant to direct sun or by a lack of nutrients, or by the beginning of a fungal attack? And how to intervene to contain the damage or save the plant when the damage has already been confirmed?

This is what we will see in this article, with the help of a series of photographs that portray different situations and different pathologies. Some photos were taken by readers of Il fiore tra le spine and portray their plants: I thank these readers for agreeing to share their photos with me, thus collaborating in the creation of the following article. (…)

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L'articolo Spots on the stem and rot, here’s what you can do to save sick succulents and cacti proviene da Il fiore tra le spine.

Many cactus and succulent enthusiasts are convinced that the cultivation of these plants necessarily involves the use of chemical products against diseases and parasites. Others consider the use of these products simply as a component of cultivation to be used in certain cases; still others are not too subtle and at the cost of having healthy plants are willing to destroy their lungs, massacre bees and poison the environment. Talking to them is as useful as trying to convince an agoraphobic to take a walk in a desert. But these people, after all, grow for collection and not for love of Nature or a sincere passion for plants. This article, the result of my personal experience and therefore not to be considered as a “lesson” in an absolute sense, may be useful to everyone else. The experience has led me to drastically reduce the use of so-called “phytopharmaceuticals” or “phytosanitary products” (which do not include fertilizers), especially toxic and synthetic ones. I have undertaken this path for some years now for reasons of health protection (mine first and foremost) and the surrounding environment, considering that many pesticides have, among the various side effects, that of killing bees. The issue relating to the death of bees may seem of little importance to the uninformed, but in reality it has enormous importance on a global level from an environmental point of view.

Let’s see in this article how it is possible to reduce the use of pesticides and fungicides, limit ourselves to products with low environmental impact such as Neem oil and copper oxychloride and still have strong and healthy cacti and succulents. (…)

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L'articolo Two useful products for keeping succulents healthy: Neem oil and copper oxychloride 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.

In the following article, we will see in detail what consists of prevention; which are the pests and diseases that can affect cacti and succulents; such as the symptoms of their action on plants, and how to carry out treatment and care in case of problems. (…)

The importance of air recirculation

The keyword for prevention is air. Air, air and more air. Therefore, airing the environments in which we keep our plants and, consequently, keep humidity rates low. Open greenhouses as much as possible throughout the period from spring to autumn, fans for air recirculation, outdoor cultivation, are all important factors to give our plants the right amount of air. Also, of course, to the use of correct substrates, draining and low humidity, plenty of light and the right fertilization regimes (an excess of nitrogen, for example, forces the growth of succulents and makes them weaker in the face of adversities), proper irrigation and, more generally, cleaning (of soil, pots, tools and instruments, etc.).

Check the plants

A good practice consists, first of all, in observing the plants carefully before their purchase, discarding those suffering, clearly attacked by parasites (such as cochineal, easily recognizable by the naked eye) or deformed at the apex due to the attack of some aphids. Once purchased the plant, it is good to flake it and thoroughly clean the roots (especially if the plant is in peat), checking the condition carefully and repot in suitable soil. Another useful trick is to immediately isolate the plant or plants that we observe in distress or on which we detect the presence of mites (for example the red spider, see below) or parasites such as cochineal. Even more important is to isolate from other plants those subject to fungal attacks: the spores can quickly pass from one specimen to another and cause real disasters. All plants, then, must periodically be checked carefully to identify any problems and isolate the affected specimens to treat them with specific products and avoid that fungi and parasites may affect other plants.

Preventive treatments

Preventive treatments can be useful against fungi and parasites, especially in two specific moments: in autumn and just before the beginning of spring. It is at these times of the year, in fact, that the combination of ambient temperature and humidity, in addition to the low activity of the plants, can favour conditions suitable for the proliferation of mites and bacteria. Before the plants go into stasis, at the end of summer/early autumn, two nebulisations at a distance of 15 days from each other with water and copper oxychloride, possibly combined with sulfur, will protect plants from some types of fungi and bacteria during the winter. In the same way, a couple of nebulisations at the beginning of spring, before watering, will contribute to the prevention at a time when temperatures tend to rise and, with them, the humidity rate due to the March/April rains. Against bacteria in the soil and root parasites, it is possible to carry out systemic treatments, i.e. special products mixed with watering water. Even in these cases, a treatment at the end of summer and one in spring, with the first watering, can be useful for preventive purposes. In these cases, it is possible to use systemic fungicides against radical rot (Previcur can be used against collar rot, while Tebuconazole can be used against fusarium and Propamocarb can be used for a wider spectrum defence). If the fusarium has already attacked the plant, it is advisable to throw away everything: plant, pot and earth.

An excellent choice, respectful of the environment and our health, is to focus on products with low environmental impact, like Neem oil, useful against infestations by mites and parasites. Always remember that chemicals, whether pesticides or fungicides, should be treated with great caution, wearing gloves and masks, as they can be harmful to health if inhaled or in contact with skin (in fact the use of many products is regulated by law and for the purchase and use of some of them, specific patents are required). An interesting alternative to chemicals against insects and pests can be to use natural remedies based on garlic and tobacco.

Some treatment, always for preventive purposes, can be done by nebulization or by the systemic way (i.e. through watering, so that the plant absorbs the product, which will go from roots to stem) even during the growing season. However, if the plants are healthy and robust, the treatments at the end of summer and the end of winter will be enough and the plants will become stronger and will be able to face and solve any problems.

Plant parasites

Plants can be attacked by plant parasites or pests. The first group includes fungi, bacteria, viruses and microplasmas. Fungi and bacteria, in particular, proliferate in the soil in conditions of heat and prolonged humidity. These are, probably, the most insidious and difficult adversities to face. This happens mainly because the presence of plant parasites is manifested only through the symptoms of the disease that they cause to the plant. In other words, fungi, viruses and bacteria cannot be seen with the naked eye, but you can see the effect of their harmful action. Unfortunately, when we realise it, it is almost always too late to save the plant.

 Fusarium  – It is the case, for example, of Fusariosis, caused by Fusarium oxysporum, a fungus present in the soil that causes withering, dry rot and the rapid decay of the plant, which first slows down the vegetation and then stains and then literally withers and dies. In the acute form, the Fusarium causes the basal rot of the affected subject, while in the slow form it causes a chronic infection that causes secretion and suberification of the plant, which slowly dies. Against this pathology, there is usually little or nothing to do, except try to deal with specific systemic fungicides (based on the above-mentioned Tebuconazole, for example). Of fundamental importance is to move the affected plant away from the others and, in case it is too late to save it, throw away plant, soil and pot (unless you want to disinfect it with bleach).

 Root and collar rots  – They are caused by fungi in persistent hot/damp conditions and by water stagnations in the soil. They affect the roots of the plants and extend to the collar causing their rot and, consequently, the death of the plant. If taken in time, for example after having noticed a slowing in the growth of the plant and its deterioration, you can intervene by flaking the specimen, removing all the old soil and cutting off all the rotten roots and then let the plant dry for at least a couple of weeks in the air but not in the sun. If the rot has hit the collar, you can try a rescue by cutting the plant to the healthy part (i.e. until the pulp is white and has no dots or brown areas). It is essential to use a sharp cutter by disinfecting the blade with alcohol before each cut, to avoid infecting the healthy part. Also in this case, after this operation, you will have to leave the plant in a shaded but very ventilated place for some weeks, until the cut part is completely dry and scarred. At that point, you can place the plant on pumice to try to promote the rooting of the cutting.

 Pythium  – It is a fungus that attacks the seedlings bringing the roots and the collar to rot. If it is not too late to intervene, the plants should be flared, the old soil removed and the seedlings left to dry. Afterwards, it is possible to use a fungicide based on Previcur, both for preventive and curative purposes.

 Powdery mildew  – This is another pathology caused by fungi, commonly called powdery mildew. It develops in conditions of low humidity and temperatures above 20 degrees and spreads through the spores carried by the wind. It reveals with white/greyish pulverulent spots, which lead to the decay of the plant. Against powdery mildew can be useful nebulizations with water mixed with sulfur.

 Sooty Mould  – Also the sooty mould is caused by fungi, a pathology that leads to the production of a dark-coloured crust or to the formation of black powder, often on cacti areoles, at the base of thorns. Are affected by it some cacti, like Ferocactus, which produce honeydew, nectar secreted by the areoles. In case of smoke, it is possible to intervene with copper sulfur, either by spraying or manually, by cleaning the affected areas with a toothbrush or a cotton bud soaked in a solution based on water, sulphur and copper.

 Rust  – This name indicates a pathology, septoria, caused by a fungus called septoria. The symptoms are yellowish spots on the stem, more or less extended depending on the severity of the attack. They are created in conditions of poor ventilation and stagnant humidity. The rust seems to particularly affect Ferocactus latispinus during the winter. It can be controlled by providing the plants with maximum ventilation and low humidity. In case of attack it is good to move the affected plants, give them more air and intervene with copper-based products.

 Botrytis  – Botrytis cinerea, also known as “grey mould”, is caused by a fungus in conditions of persistent humidity and poor aeration. It creates spots initially dark green with yellowish edges. Then the spots are darker until they become brown or black and are covered with grey mould. The best prevention is a good recirculation of air and space between one plant and another. In case of an attack by botrytis, it can intervene with systemic fungicides in association with copper oxychloride. Isolate the affected plant immediately to prevent the spores from passing on to other specimens.

Animal parasites

Even against animal parasites, the best weapon remains prevention, understood as proper cultivation aimed at obtaining robust and healthy specimens. However, some bad encounters between our plants and some parasites (or lice, as they are commonly called) can always happen.

 Cochineal  – These insects are among the main enemies of succulent. They attack plants like the Opuntia, but they do not disdain the other Cactaceae. They can be of three types: waxy cochineal, mealybugs and shield. They usually strike the apex of the plants, but they can nest, also between the roots when the soil remains dry for long periods. In the latter case, the attack is more dangerous, because we only notice it when we repot or if we are very careful if we see that the plant has blocked the growth and is declining without any other apparent causes. The mealybugs suck the sap from the succulents, weakening them, and compromising their growth. The waxy cochineal nestles between the coasts of the Cactaceae or around the areoles, is a couple of millimetres long and secretes a layer of wax. The cotton cochineal, as its name says, produces small white woolly balls. It threatens the apex of the cacti or between the leaves of the succulents and sucks the sap. If the infestation is limited, you can manually remove the mealybugs or crush them with a toothpick. In the case of root cochineal, it is necessary to remove the soil, clean the roots thoroughly, shorten them and, immerse the root system or the whole plant for a few minutes in a contact insecticide and then let to dry for a few days before repotting in the new soil. The cochineal shield is more difficult to remove manually, which also reproduces quickly and, if left to do, can literally cover the plant seriously compromising its growth until it decays. It clings tenaciously to the trunk of the cacti, is white/greyish and has the typical shield shape. They can be removed with a toothbrush, or removed with a nail, but it is not always an easy action. Specific systemic insecticides, or summer mineral oil, can be used against mealybugs. It is also useful alcohol (diluted in water and nebulized), which dissolves the waxy protection produced by these insects and makes them more vulnerable to a subsequent treatment based on specific products. In case of radical cochineal, it is good to immerse the roots (or the entire plant) for a few minutes in a solution based on water and specific anti-cochineal products. When crushed, the cotton cochineals produce a red substance that was used as a textiles dye by Mexican populations.

 Red spider  – This is a small phytophagous mite (Tetranychus urticae), not visible to the naked eye. It proliferates in dry, warm conditions, so it can develop in the hot season if the waterings are very spaced, and the climate is particularly dry. It strikes the apex of the cacti, where the tissues are more tender, and causes secretion on the epidermis which assumes a grey/reddish colour. Growing up, the stem is chapped and aesthetically compromised. At the same time, a massive attack by the red spider can slow the growth of the plant and compromise its proper development. Good prevention against these mites consists in the cultivation of cacti in full sun so that the epidermis hardens and is less subject to the attack of the red spider. At the same time, outdoor cultivation encourages the presence of insects competitors able to contain the development of this mite. A red spider infestation can be countered by systemic and acaricide insecticides such as kelthane, dicofol and sulfur products. It is important not to use the same active ingredient often because the red spider quickly develops acaricide-resistant strains.

 Nematodes  – They look like little worms. They develop in fresh and humid soils and can penetrate inside the roots of the plants blocking the lymphatic flow and leading the plant to growth block, decay and death. They can be easily noticed only in case of repotting: the roots have swellings, nodules a few millimetres in size. As a preventive measure, it is advisable to take a good look at the roots of freshly purchased plants or during each repotting. In the presence of nematodes it is necessary to cut the roots as much as possible and throw the pot and all the old potting soil. Some growers recommend soaking the roots for about twenty minutes in water at 50°. When you notice the presence of these nematodes, often it is too late because they move from one root to another and eradicating them is quite difficult. It is not by chance that several experts advise throwing away the plant in case of an attack by nematodes.

 Aphids  – Fortunately, they do not frequently attack succulents. These are green or black insects that can weaken the affected plants by opening the door to viruses. Specific products (such as Movento) are easily found against aphids, although they can be removed with soapy water (for example, using a Marseille soap diluted in water).

 Metcalfa  – They are small white or pale green insects and appear from the middle of May. They suck the sap of the plants and can facilitate the onset of honeydew and soot. They can be counteracted with specific insecticides, such as those used against cochineal.

 Thrips  – They are very small so that it is almost impossible to see them with the naked eye. They usually attack the flowers, attracted by the pollen, causing dryness, malformation to the petals and favouring the attack by viruses. Against these insects, you can use blue chromotropic traps, or Marseille soap and water or specific insecticides (dimethoate).

 Swarming Fly  – The larvae of these Dipterans are dangerous for seedlings. In fact, they nest in the soil and attack the collar and the roots of the young plants, causing their decay and subsequently their death. The swarming fly is attracted by humid soils rich of organic substance (e.g. peat); for this reason, it can easily attack the seeds, which for the first months must have the soil always humid. The larvae of swarming fly are fought with specific insecticides to be administered together with the waterings.

 Snails and ants  – Among the potential enemies of cacti and succulents there are also snails and ants. Snails can cause considerable damage because they eat the fleshy leaves of succulents and can attack the apical part of cacti, which is more tender. When they are found, they must be immediately removed from the plants, whilst to keep them away, we can resort to the old system of the saucer with some beer, which attracts them and the stuns. There are also specific products in granules to be spread on the surface of the substrate: for snails, they are toxic and eliminate the problem before the molluscs attack the plants.
Ants are not dangerous, but they steal the seeds of succulents and are attracted to the nectar that the glands of some cacti produce (e.g., Ferocactus). They can also carry insect eggs that are harmful to plants. They contrast with specific insecticides, often powdered, to be spread around pots to keep them away.

Wondering what is the right soil for cacti and succulent plants? You can read here…

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Correlated articles

Cactus cultivation cards
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 Diseases and pests of cactus and succulents: how to recognize them and how to prevent their attacks proviene da Il fiore tra le spine.

First of all: why should we fertilize our cacti and succulent plants? Let’s say right away that fertilization (or fertilisation, or manuring or mineral nutrition) is necessary for any plant grown in pots, since the amount of soil available is limited and, sooner or later, nutrients will begin to run low. Fertilizer nourishes the plant, enriching the soil of those elements which, through the time, are absorbed by the plant or washed away by the waterings. Succulent plants should be regularly fertilized to ensure that the right quantity of nutrients is always available during the growing season. For cacti and succulents, however, generic fertilizers should not be used. In other words, a fertilizer commonly used for ornamental, leafy or fruit plants is not at all appropriate for a cactus plant. It is necessary to resort to specific fertilizers, specially balanced for the succulents. Otherwise, the risk is to irreparably compromise the growth and the physical appearance of the plant, making it weak and radically different from the specimens of the same species that grow in the wild.

In the following article we will go deeper into the subject, let’s see what elements succulents need, how the suitable fertilizer must be composed and how much to fertilize during the year. (…)

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L'articolo When and how fertilize cactus and succulent plants to have aboundant blooms proviene da Il fiore tra le spine.

Do cacti resist frost? In winter, do succulent plants have to be kept indoors or can they stay outside? And what are the minimum winter temperatures they can tolerate? Even among experienced growers, the minimum temperatures of cacti and succulents are still debated today. I tackle the topic starting, as always, from my personal experience, which is my only way to have accurate data, found in the field, related to my system and my growing conditions, here in North of Italy. Let’s say right away that during winter I keep most of my plants in the greenhouse. It is a large greenhouse of 60 square meters and with a height, at the top, of 4 meters. These dimensions guarantee a satisfying volume of air, which in turn prevents moisture stagnation, the first real enemy of cacti and succulent plants in winter.

Let’s see, in the following article, the various factors that influence the resistance of cacti and succulents to cold. At the end of the article, you will also find a schedule with the minimum temperatures tolerated by the various families of succulents. (…)

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L'articolo Succulents and cold: how to care for cactus in winter and the minimum temperatures tolerated proviene da Il fiore tra le spine.