Cactus e Dintorni

  • Increase font size
  • Default font size
  • Decrease font size
Italian - ItalyEnglish (United Kingdom)French (Fr)Español(Spanish Formal International)

The hopes, pleasures and disappointments of every aspiring succulent grower

The following article is the summation of all the information patiently gathered from many enthusiasts’ personal experiences as well as my own. It was not easy to put together different, at times apparently conflicting, opinions and practices. You must take into account that growers have to cope with diverse climate conditions and therefore develop many different approaches to the task of seed raising, so much so that people say there are as many sowing methods as there are sowers.

Young seedlings dry up if not kept moist, rot if watered too much, need plenty of light but might get burnt if placed in full sun: quite a puzzle indeed.
I strongly advise building a propagator which allows you to sow seeds methodically, providing at the same time a suitable environment for seedlings growth so that young plants are well-developed and ready to go through the winter season without difficulty. However, seedlings might be profitably kept growing during their first winter as long as adequate light and temperature are provided, for example inside a heated cabinet.

Seeds can be sown any time of the year as long as we provide the right conditions in terms of light (8000-15000 lux for 13-15 hours), temperature, humidity, air circulation, soil and seed viability. Natural light is always the best but, at latitudes higher than 45 degrees north or south, it is usually not strong enough for seeds to sprout thus making artificial light indispensable. Considering that seed merchants normally supply seeds from the previous season’s crop during the first months of the year and also that the sooner they are sown the better it is (with a handful of exceptions) and lastly that early sowing ensures a longer growing season, we reach the conclusion that the best sowing period is during January through to March, if we avail ourselves of a heated propagator, or April to May if we intend to rely on natural light and warmth. Despite having a propagator at my disposal, I still prefer to sow between the end of March and early April; this way the heating system only operates during chilly nights, which might still occur at this time of the year, whereas the light provided by the sun is already strong enough. I sincerely recommend that those growers who own a glasshouse, even a small one, should place the propagator inside the structure. If necessary, we can limit the amount of solar radiation by laying a sheet of paper on top of the cultivation module.

Normally, during the period preceding germination, it is best to maintain a controlled environment with nearly 100%1 of relative humidity, a maximum and minimum temperature of about 25°C (77°F) and 18°-20°C (64-68°F) respectively and 13 hours of bright indirect light (thus recreating natural conditions). As for the exceptions, this is what the company Mesa Garden suggest:
- 22°C (72°F) in the daytime with 13 hours of light and 17°C (63°F) at night-time for: Ancistrocactus, Blossfeldia, Echinofossulocactus, Frailea, Lobivia, Notocactus, Oroya, Pyrrhocactus, Rebutia.
- 38°C (100°F) during the day and 13 hours of light wih a low of 17°C (63°F) at night plus scarification2 for Opuntia, Tephrocactus, Grusonia, Adansonia, Manihot, Jatropha, Brachychiton.
- 17°C (63°F) during the day, 11 hours of illumination; 17°C (63°F) at night. Sow seeds in autumn-winter for: Tylecodon, Sarcocaulon, Dioscorea. A high of 17 to 20°C (63-68°F) is also suitable for seeds of Crassula, Duddleya, Sedum, Adromiscus, Cotyledon, Graptopetalum, Kalanchoe, Pachyphytum, Sempervivum, Tacitus, Anacampseros, Parodia, Echinocereus, Echeveria, Argyroderma, Cheiridopsis, Conophytum.

Generally speaking, it is best to keep the minimum temperature above 16°C (61°F) while the high may be allowed to reach 30°C (86°F) or so but without exceeding it considerably as this can temporarily arrest the germination process. There are some exceptions though, such as cold-hardy succulents which require higher temperatures and also Haworthia, Othonna, and Pelargonium which on the other hand need lower temperatures; you will find more detailed information in the chapters below dedicated to the single genus or species.

A soil that is prevalently mineral and slightly acidic (ph around 6.5) has the advantage of being generally healthier and less likely to develop rot and mildew than one with a high content of organic matter (humus, leaf mould etc.). However, this risk can be reduced by mixing into the potting soil some antifungal powder. Disinfection of the substrate (pasteurisation) can also be obtained by pouring boiling water over the soil or baking it in a domestic oven for about an hour at a temperature of 70-80°C (158-176°F), but not higher so as not to kill beneficial bacteria. You might as well use a microwave oven (30 minutes at full power spreading the soil evenly to form a layer approximately ten centimetres thick). In order to prevent unpleasant odours from being spread through the room, slip the soil, that you have previously moistened, into an adequately sized plastic bag then squeeze it to expel the air and seal it. Peat does not need sterilising. This operation helps to eliminate fungal spores or undesirable seeds which may be present in the soil and favours germination of 'difficult' seeds. There are different schools of thought about the advantageousness of this operation. Personally I believe it to be, in most cases, pointless so long as we use inert materials, packaged peat and potting mixes. In contrast, it is highly recommendable to sterilise the propagator, together with the tray and every single container, using sodium hypochlorite (bleach) or lysoform (1 part to ten parts of water), rinsing thoroughly afterwards. As for seeds, I normally mix them with some anti-cryptogamic powder so that their surface is coated with a thin layer of product.

All growers are agreed on the fact that the soil mix should be quite porous, not too rich in humus and have a fine texture, though not excessively. However, there are different opinions when it comes to the actual composition: some use sand, perlite and universal potting mix (which can be substituted by garden soil) mixed in equal parts; others opt for half sphagnum peat moss (or leaf mould) and half perlite mix. As far as I am concerned, I mostly use a mixture of 80% pumice (either pozzolan or lapillus can be used intead, also mixed together) and 20% of ericaceous compost. Another soil mix that I have used successfully is 10% leaf mould, 30% sieved garden soil, 30% non-calcareous sand (1 to 3 mm in diameter) and the remaining 30% pumice stone (lava or pozzolan are good substitutes). On top of the soil I normally spread a 1-centimetre-thick layer of sand or pozzolan that I have previously sieved twice to eliminate both dust particles (1 mm mesh size) and coarse fragments (4-5 mm mesh size). You may also add a tablespoon of bone meal or 5 grams of mineral perphosphate per litre of mixture, though some think it is preferable not to fertilize before germination. Non-calcareous sand3, such as that used for sandblasting house walls, is commonly available at wharehouse stores; all the other materials can be purchased in specialised nurseries. Make sure that soil components are dry before sieving. You might also try varying the composition to obtain your own personal mix, especially if certain materials cannot be easily found in your locality; keep in mind that seedlings must be left undisturbed in their sowing mix for about one year.

By way of information, this is the advice that Mesa Garden Company (New Mexico) give to customers who purchase their seeds: the substrate must have a sand-like structure, contain microorganisms and little organic matter which can harm the delicate roots of seedlings. A combination of 80% of loam4 and 20% of sphagnum peat and possibly some sand makes a good multi-purpose substrate.

These procedures are intended to break dormancy which characterises some types of plants (mostly the so called cold-hardy cacti) and whose function is to preserve seed viability.
Some seeds must undergo stratification which is some sort of artificial winter: they must be stowed in the refrigerator for at least two months at a temperature between 1 and 4°C (34-39°F), having been moistened beforehand. Cold-hardy plants require lower temperatures, so seeds should be enclosed in plastic bags then sealed and kept in the freezer overnight; leave them to thaw at room temperature during the following day. Alternatively, sow in the autumn and expose the seed to the cold throughout the wintertime so that germination will be triggered by the spring warmth.

Scarification helps water penetrate, in different ways, into the seed thus initiating the germination process. Seeds with a hard coat can be, depending on their type, either softened by soaking them in hot water or vinegar (check if the seed coat swells), scarified with sandpaper or a file or chipped with a needle. You can also immerse them in sulphuric acid (96%5 concentration), rinsing thoroughly afterwards so as not to cause any harm to the embryo. Very big and hard seeds can be scarified with the aid of a grindstone. The abrasion must be executed far from the hilum until a small portion of the embryo is uncovered.

In a few cases dormancy is broken by extreme heat or digestive enzymes such as papain (extracted from papaya fruit) or pepsine which is secreted by the stomach of animals and has a proteolitic action. I have no experience of these last two methods, therefore I cannot give any personal advice. Some seed coats contain chemical inhibitors that can be neutralized by washing the seeds in a solution of water and lemon juice.

Fill the bottom of pots, previously disinfected, with lapillus, pumice or clay granules up to one or two centimeters, then pour the mix which must be perfectly dry to within few centimetres of the rim. Spread a 1-cm-layer of quartz sand (available at aquarium shops) on top and tap gently to let the soil settle. Before sowing, it is recommendable to run a test with a pot with no seeds, watering it from below: the substrate should get evenly moist up to the surface without collapsing.
In the case of minute seeds, scatter some fine sand over the potting mix before sowing then sprinkle some water so as to allow seeds to settle among the sand grains. Percentage of germination is higher with demineralised water. Such seeds must not be covered.

With medium-sized seeds we use a different approach: sand should be coarser, roughly the size of the seeds, and has to be sprinkled over the evenly sown seeds until they are only partially covered. Use sand only, not soil.

I advise soaking large seeds, which are prone to rot and mildew, beforehand in an anti-cryptogamic solution for 24 hours. Proceed to sow round-shaped seeds pressing them delicately into the soil to create a slight depression on the surface, finally cover them with a layer of grit as thick as their diameter.
Flat seeds as well as elongate ones, on the other hand, need to be poked into the substrate using tweezers with the hilum pointing downwards until the other end is only barely visible. Do not lay this kind of seeds on their flat side; make sure they are sown perpendicularly to the surface. Finish with a 3 to 5 millimetre-thick layer of sand, best if quartz sand.
Coarse sand does not hinder germination while on the other hand fine sand usually does, as it tends to clog and choke the seeds. As you sow, write down a list with plant names followed by a cipher specifying the position occupied by the corresponding pot within the propagator (for example 05/23, the first number representing the year and the second one the sowing order). Write the cipher with a water-based marker on the side of the pot as well. Make sure the tray is perfectly level and the seeds are not disturbed. If your packet contains a reasonable amount of seeds I recommend you sow half of them in case you don't succeed due to diseases or other problems, so that you can try again some other time.
Once the seeds have been sown, prepare a lukewarm solution of rain water6, previously boiled, and copper oxychloride (such as Cupravit micro blu ® 1gr/litre) then pour it gently into the tray. As soon as the water reaches the surface of the pots by imbibition, get rid of the excess liquid that might linger on the bottom with the help of a sponge. If by any chance one of the pots should take such a long time to get wet as to be still dry on the surface after fifteen minutes, take it out of the tray and immerse it in a container with deeper water until moisture has spread to the top.

For the next two months we must ensure that the tray is constantly covered by a film of water, often keeping an eye on that during hot spells. We must neither let the soil dry out, which would stop the germination process irreversibly, nor water too much, thus increasing the risk of damping off. Avoid overwatering during this phase. Before the seeds start sprouting, use only plain water with no anti-cryptogamic substances which might delay germination. Cover the propagator with its own lid setting the thermostat to the temperature that the sown species require during the daytime, knowing that little fluctuations can be tolerated. During the night, as the temperature drops outside, the internal temperature will not reach the selected value but instead will stabilise somewhere between 17 and 20°C (63-68°F), as desired. During the day the heating system will be activated by the thermostat only when necessary (unless the weather is very cold). If the winter in your area is harsh and you notice that the heating is always on without reaching the necessary temperature you may connect another resistor in parallel or use a more powerful heating cable. If, on the other hand, you decide to sow in early April, you only need to set the minimum temperature on the thermostat (between 17 and 20°C - 63/68°F - according to the genus) since during the day the sun should be already strong enough to ensure the necessary temperature. However, keep the temperature inside the propagator always in check preventing it from getting too high; should that happen you must provide adequate ventilation at once.
It is advisable that you avail yourself of a max/min temperature recording thermometer. Avoid sowing seeds requiring different treatments in the same propagator. Once all the seeds are sown, you can place a newspaper sheet on top of the lid in order to cast some light shade; remove it as soon as the first seedlings appear. Get rid of condensation that may form on the inside of the glass. Germination starts after 2 to 4 days for some species (Astrophytum, Stapelia, etc.), or after 10 to 12 days for others; exceptions are Opuntia, Tephrocactus, cold-hardy cacti, Pelargonium, some Mesembs and a few other genera which may take from one week up to one year to sprout. Large hard-coat seeds, if not scarified, might take a long time to germinate too. Anyway, if none of the seeds has emerged after a month, let the soil dry out for a week, stratify and re-start the whole cycle, even a few times if necessary. Germination, even for seeds of the same species, may be erratic and spread out in time, depending on seed vigour and genetic characteristics.

Many growers, especially if germination is very difficult or slow, resort to a particular sowing method which consists in placing the pots, after having sown the seeds and wetted the soil, inside polythene bags, best if they are self-sealing. This ensures a high level of humidity at all times and as long as the bag is sealed there is no need to water. When seeds have sprouted, gradually open the bag or make a few cuts along its sides so as to let the air circulate but make sure the soil never dries out. Seedlings can grow inside the bag for one or two years and up to three in the case of slow-growing species. This practice however is subject to a number of variations:
Soil: some use very soft, light, non-fertilised substrate like the multi-purpose mix normally used for house plants; others one part of peat moss and one of washed sand. Some growers use fertiliser and some don't, some people pasteurise the mix and some think it is detrimental.
Water: Some use demineralised water, some boiled rain water, some others water obtained from reverse osmosis.
Light: Some rely on natural light, others resort to neon lamps.
Instead of a plastic bag you can also use clingwrap to cover the pots together with the tray below them.

Acanthocalycium, Gumnocalycium, Melocactus, Notocactus, Rebutia. The seed raising mix should be composed of two parts of inert materials and one of beech-leaf mould or ericaceous compost.
Ancistrocactus, Astrophytum, Echinomastus, Gymnocactus, Glandulicactus, Neolloydia, Thelocactus. Seedlings are prone to damping off so it is fundamental to keep humidity levels in check and raise the seed in 100% mineral soil.
Ariocarpus. Not difficult from seed; prick out after three years during the rest period. It prefers a night temperature below 18°C (64°F), an 80% calcareous mineral mix (lava, pumice and granite) with the remaining 20% composed of chestnut-leaf mould or peat. It is possible to use artificial lighting in 12-hour-cycles. Its slow growth can be accelerated by grafting it onto Echinopsis. Preferable though not necessary is sowing with the plastic bag method.
Aztekium, Geohintonia. These are difficult genera (particularly the first one) in that they are extremely slow-growing which leads almost inevitably the plants to rot. Try sowing seeds in quartz grit and using the plastic bag method (or cover with clingwrap to be left at least for a year; watering and feeding from below); artificial lighting must be turned on 24 hours a day. Graft plants after one or two years at least on chalk with the addition of quartz sand and a sprinkling of clay to provide the minerals the young plants need. Alternatively you might as well try to graft one-month-old seedlings on Pereskiopsis velutina then re-graft after one year on a more suitable rootstock (Myrtillocactus geometrizans, Trichocereus spachianus, pachanoi, or bridgesii, Cereus jamacaru, peruvianus, etc.).
Blossfeldia. Very slow and difficult to germinate but if we procure fresh seeds and sow them in sterilised mineral soil7 inside a plastic bag the percentage of germination is usually satisfying. Do not alter the growing conditions for at least 3-4 years until the seedlings have reached a diameter of 4 to 5 millimetres. Keep the pots away from direct light during germination.
Cold-hardy cacti: In my opinion the seeds of Sclerocactus, Pediocactus, Toumeya, Uthaia, Escobaria, Neowerdermannia Austrocactus as well as Opuntia, Tephrocactus, Mahuenia, Sophora germinate better if scarified8 by soaking in a 96% solution of sulphuric acid for 8 to 10 minutes and immediately washed afterwards. Best sown in 100% mineral soil. Some growers use different methods: first wash the seeds in water and lemon juice then scarify and stratify by stowing them in a freezer overnight and letting them defrost during the day, repeating the cycle for two weeks approximately. Germinate in a suitable substrate9 with 16 hours of light at about 30-40°C during the day and 10-15°C  at night. Seeds of Opuntia and Tephrocactus can also be soaked for 12 hours in a solution of water and vinegar and after that another 12 hours in pure water. Then you may follow three different procedures:
a - sow seeds in sterilised pots and cover with clingwrap; if they do not germinate after 2-3 weeks re-start the process first stratifying then sowing them again;
b - sow in moistened cotton wool or paper towel and as germination begins delicately remove seedlings and pot them up in cactaceous mix; if germination does not occur proceed as explained in a);
c - sow in January placing the pots outdoors in full sun if local weather conditions allow; the ideal temperatures are a low of about -5°C and a high above zero (between 5 and 10°C. for two or three months; after that seeds should be placed in a propagator and kept at the temperatures indicated above.
Seedlings of Austrocactus, Escobaria, Pediocactus, Sclerocactus, Toumeya and a few others are very vulnerable during the initial stages of their life, therefore an early graft onto Preskiopsis is recommendable followed by another graft after one year onto Opuntia, Echinopsis, Echinocereus or other hardy cacti10.
Epiphytic and climbing cacti: (Epiphyllum, Schlumbergera, Selenicereus, Aporocactus, Aporophyllum, Heliocereus, Epicactus, Hylocereus, Nopalxochia, Rhipsalis). Seeds are prone to fungal diseases, therefore need to be washed and disinfected beforehand. They require temperatures between 22 and 28°C.
Echinocactus horizonthalonius, polycephalus, xeranthemoides. It needs scarification by soaking in sulphuric acid for five minutes and, if growth is stunted, grafting. The soil must not contain organic matter.
Epithelantha. It is preferable that you sow inside a plastic bag as described in the previous chapter. Avoid pricking out during the first year. Soil should be 100% mineral.
Eriosyce. Sometimes breaking dormancy may be difficult, therefore stratification is advisable. Spraying water is helpful; grafting of young specimens is essential.
Frailea. Use only freshly harvested seeds, one-month-old at the most.
Parodia. The soil should consist of half peat and half sand or perlite. Seeds may take up to one year to germinate. The plastic bag method is effective.
Pelecyphora (Encepholocarpus). Seedlings sprout quite easily but are difficult to grow so grafting is advisable. Use 100% mineral soil.
Seeds of species from Central and Tropical America like Melocactus, Discocactus, Rhodocactus, Arrojadoa, Pereskia, Pereskiopsis, Mammillaria nivosa, Backebergia, Uebelmannia require sowing temperatures between 25 and 30°C (77-86°F) and a minimum of 20°C (68°F) in the wintertime.
Strombocactus. The mix shoud contain 50% of peat and the remining half perlite. They are slow-growing. It is preferable to sow in a plastic bag and prick out after 3 years.
Sulcorebutia. Use fresh seeds only and sow at 25° (77°F) during the day and 20°C (68°F) at night. Let the air circulate immediately after germination11.
Turbinicarpus. Use preferably the plastic bag method and 100% mineral soil.

Adansonia. Use the plastic bag method and sow one-year-old seeds in June at a temperature slightly above 30°C (86°F).
Aloe. Seeds must be fresh and germinate best at temperatures between 20 and 22°C (68-72°F) at night and around 30°C (86°F) during the day. Prick out seedlings after one year and plant in a mix containing 50% perlite or sand, 40% peat and 10% leaf mould. Overwinter seedlings at a minimum of 12°C during the first year.
Adenium. Keep the seedlings growing during the first winter. African succulents with large seeds. Remove wings from seed when present, scarify those with a hard coat then sterilise and wash thoroughly. They can easily rot due to excess humidity and fungal diseases, therefore they need to be examined on a daily basis and if you notice any signs of infection they must be immediately cleansed, disinfected and sown again.
Anacampseros. Use cactaceous mix with the addition of quartz sand. They germinate easily at about 16°C (61°F) but are slow-growing. Seeds do not stay viable for a long time.
Asclepiadaceae. They require a temperature of 26 to 28°C (79-82°F); remove the parachute-like pappus before sowing. Use fresh seeds.
Astroloba. Sow fresh seeds only.
Bromeliacee. Dychia, Hechtia, Pitcarnea, Puya: they germinate best in peaty soil and a shady environment.
Beaucarnea, Dasylirion, Nolina. Seeds need to be shelled prior to sowing.
Bursera, Fouquieria. They are slow-growing.
Calibanus. Normally it germinates quite easily but it is preferable to store the seeds in a freezer for 15 days and after that scarify them. Keep the seedlings growing throughout the first year.
Cissus, Chorisia, Cussonia, Cyphostemma, Jatropha. These seeds have to be washed thoroughly then soaked in water for 48 hours. After this, scarify them and sow, keeping humidity level in check since they are prone to rot. Use fresh seeds and soft peat-based soil. They require temperatures between 25 and 27°C (77-81°F). Remove the pulp from seeds of Cyphostemma; they may take several months to emerge.
Crassulacee. They need fresh temperatures (17°C/63°F at night and 20°C/68°F during the day), a mix composed of 50% peat and 50% sand. Seeds can be as fine as dust. Cotyledon and Tylecodon are short-day species, therefore is best to sow in the autumn. Use preferably the plastic bag method.
Dasylirion. Sow in sandy soil and maintain a temperature of about 18°C.
Dioscorea (Testudinaria). Easy to grow but it is essential that you never allow the soil to dry out at least for the first year.
Euphorbia. Tricky to raise with losses in germination. Sow at 25/28°C (77/82°F), providing dry air and plenty of light after seed emergence and lowering the temperature to 20°C (68°F).
Gesneriaceae (Rechsteineria, Sinningia, Streptocarpus). Germination is fairly easy; it is useful practice to scatter a thin layer of sieved peat over the raising mix.
Haworthia. Sow keeping the temperatures between a low of 8°C and a high of 16°C; soil should be composed of 70% sand, 20% peat, 10% leaf mould or ericaceous compost.
Marah. These caudiciforms take one year to germinate.
Mesembryanthemums. Soil: 50% garden soil and 50% sand or 2 parts of Beech litter, 2 of fine grit and 1 of sand. Spray some antifungal product as soon as seeds emerge; germination is usually quick at 18-20°C (64-68°F), but sometimes it might take quite a long time. Avoid great oscillation in day/night temperature range and light intensity. Feeding is not strictly necessary. It is very important to provide adequate ventilation, plenty of light and reduce air moisture after seeds have emerged. These seeds remain viable at least for five years and are best sown when they are not too fresh. During thei first winter keep seedlings at 8°C (46°F) approximately, making sure they receive adequate light and the soil never dries out. Experienced growers sow short-day species like Argyroderma (quartz-loving), Frithia, Dactylopsis in the autumn (October to November) ensuring a temperature of about 20°C (86°F) for a healthy growth. Dactylopsis is best sown in a substrate containing nothing but crushed red brick (or pozzolan) and lava. Lithops should be sown in pots at least 10-cm deep. Conophytum should be sown preferably in early autumn, providing adequate artificial warmth and light all through the winter; alternatively you might as well sow at the end of the winter season. Spray water on seedlings daily and feed once a week with more dilute fertiliser than normal until the end of June; after that place young plants in a shady place and spray water lightly on them once every two weeks until the end of September. You can now start treating them like adult plants; they do not need pricking out as they can stay in a shallow large pot for many years. Rhinephyllum: sow on sand. Dinteranthus: slow and difficult to germinate, it grows on quartz. Some growers advise covering pots with cling wrap and exposing them to sunlight for a total amount of 100 hours in order to reach the temperature threshold of 65°C (149°F) necessary, according to this theory, to break seed dormancy. Treat seeds normally after that without removing the plastic film; germination should then occur within two or three weeks.
Othonna. These short-day plants are not easily grown. Sow in the autumn or spring with temperatures in the range of 5 to 10°C (41-50°F) with 11 hours of light. It is important to remove the parachute (pappus) before sowing and that the seed be inserted into the substrate vertically but with a slight inclination. Choose a location in full sun and prick out as soon as possible.
Palma, Cycas. They germinate best at 28°C (82°F) approximately.
Succulent Pelargoniums. Generally they are quite easy; seeds emerge in late summer at about 6-12°C (43-54°F). Remove the parachute and ensure air circulation immediately after germination. It is useful to soak the seeds overnight then stratify them as they are usually dormant; in this case in fact it might take up to one year for them to emerge. Poke the seeds into the soil leaving the tail-like extremity out.
Plumeria. Remove wing; they resent cold and wet during the winter.
Pseudolithos. Soil: completely mineral made up of pumice, vermiculite, lavic sand. Do not allow the soil to dry out for the first 18 months.
Rechsteineria. Young seedlings must be kept moist for 8 to 16 months.
Sarcocaulon. Winter-growing; sow in late autumn.
Stapelia. Seeds germinate easily but do not stay viable for a long time.
Welwitschia. We can lengthen viability by storing seeds in a freezer. Remove wings and sheath prior to sowing. Seeds are coated with a yellow-coloured chemical inhibitor wich must be washed away by rinsing and soaking in a solution of water and fungicide overnight. They can be sown in moistened paper towel then potted up once sprouted or sown in a mix composed of 2 parts sand, 2 parts perlite, 1 part peat and 1 part sandy soil or ¾ lapillus, ¼ universal mix. Use a clay pot at least 30 cm high for every single seed; the seedling can grow there for up to five years. You can also cover the pots with a plastic bag but make sure to remove it as soon as germination begins. Keep seedlings in a warm and bright location but avoid direct light. Viability depends on provenance and age of seeds. Sow in May/June at a temperature of 28-30°C (82-86°F) or in a bottom-heated propagator, taking the pots out of it as soon as cotyledons appear. Water regularly without allowing the soil to dry out and keep seedlings warm during the first winter. Scatter a layer of quartz grit. During the first two years they are particularly susceptible to fungal diseases and may suffer from lack of moisture.
The following genera, due to the unique habitat they live in, the particular conditions their seeds need in order to germinate as well as the fact that they are quite difficult to grow, are best sown after stratification and, when possible, scarification: Ariocarpus, Coloradoa, Calibanus, Discocactus, Encephalocarpus, Epithelantha, Neogomesia, Obregonia, Pelecyphora, Sclerocactus, Solisia, Uebelmannia, Echinomastus, Mammillaria wilcoxii, Mammillaria wrightii, Mammillaria solisioides, Mammillaria tetrancistra. If a specimen is too hard to grow we can resort to grafting. Excellent rootstocks are Pereskiopsis velutina (easy from cuttings), Trichocereus bridgesii (quickly raised from seed), Eriocereus jusbertii. Some tropical plants in the Asclepiadaceae family like Caralluma, Trichocaulon, Tavaresia, especially while still young, are difficult to grow especially in the wintertime, therefore it is recommendable to graft them onto tubers of Ceropegia woodii.
Minute seeds and all those which are difficult to germinate or grow benefit from the use of demineralised water, of an artificially lit tray (as described in 'the propagator' paragraph), of soil disinfection and of the plastic bag sowing method (or alternatively the pots might as well be covered with clingwrap).
Seeds of Conophytum, Kleinia, Massonia, Mitrophyllum, Monilaria, Othonna, Tylecodon (Cotyledon) and some winter-growing Pelargoniums can be sown in the spring or the autumn although you may expect delayed and erratical germination so don't throw them out.

After emergence seedlings go through the most delicate phase; they need ventilation (but not drafts), plenty of light and... our watchful loving eye. Therefore keep humidity levels always in check and gradually increase the air flow; this will also reduce the risk of plants being burnt by excessive temperatures which may occur inside the propagator (even more than 50°C/122°F). At this stage seedlings should be kept at a temperature 3-5°C lower than that required for germination; after this you may allow the temperature to rise up to 30-38°C (86-100°F) as long as good ventilation is provided.
Remove the lid from the propagator and place a wooden frame on top of it then stretch a fine plastic or wire12 mesh and mount it onto the frame; not only will this protect young plants from the harsh sun but it will also allow air to circulate thus promoting more vigorous growth and preventing the development of moulds and fungi.
A close inspection will tell if lighting is appropriate: too much light makes the plants take on a reddish hue while poor illumination causes them to become thin, spindly and yellowish. Large seed coats may be a source of diseases after germination has occurred, therefore they should be removed with a pair of tweezers or blown off.
The following genera need ventilation and a reduction in the humidity level immediately after emergence as they are particularly prone to fungal diseases: Aloe, Agave, Adenium, Anacampseros, Ariocarpus, Astrophytum, Caralluma, Coryphantha, Discocatus, Echinocereus, Echinomastus, Epithelantha, Escobaria, Euphorbia, Ferocactus, Frailea, Gymnocactus, Melocactus, Pachypodium, Plumeria, Pyrrhocactus, Stapelia, Thelocactus, Turbinicarpus, Hoodia, Trichocaulon.
Newly emerged seedlings are extremely delicate and their root may be thinner than a hair, therefore they must not be disturbed, not even sprayed but watered with the same method used before germination, that is to say by topping up the thin film of water (never from the tap) covering the tray when necessary. If after emergence seedlings stop growing and do not open cotyledons, insufficient temperature is most likely the cause. In order to raise the temperature and set things right enclose the pot in a transparent plastic bag. After a month check if mould has appeared on the surface; if that is the case, dust with an anticryptogamic agent allowing air to circulate and soil to dry a little bit for 3-4 days; after that sprinkle a thin layer of sand on the surface and start watering again. You may also begin to spray the seedlings with 1% solution of water and mineral perphosphate or water and one part per ten thousand of 66 F ® (hormone stimulant produced by L.Gobbi Co.; alpha-naphthylacetic acid-based) once a week for four weeks. If you notice that some roots are bare, bury them with the help of a sharp pencil. Keep on watering from below. After three months some plants will have developed spines, others leaves and their root system will already be established. The shading net can be removed during the morning hours when the sun is not too strong. Since not every species grows at the same rate it is advisable to separate the fast-growing ones from the rest allowing them to receive a larger amount of water so that they can grow at their full potential.
After five or six months after germination, further reduce humidity and water periodically also from above, allowing the soil to dry out for a few days in between and try to gently loosen the surface with shallow motions from time to time so as to ensure air circulation among soil particles. Throughout the first year seedlings have to be raised in a humid substrate, though never waterlogged, and soil composition must contribute to good aeration. Keep young plants lightly shaded always checking on their colour. By doing this we encourage plants to develop a strong root system, and get used to the conditions they will experience once they have attained maturity and we also reduce the risk of damping off.
At this stage it is advisable to apply a 3 parts per mil solution of fungicide of the kind used against peach leaf-curl (copper oxychloride) or a one part per mil solution of Propamocarb (Previcur ®), a systemic fungicide effective against root collar rot. Later, we can spray Iprodione (Rovral ®) at one part per mil against grey mould (botrytis). Young seedlings need to be protected also against parasites that might attack the roots (such as larvae of white fly or other insects) or the aerial part. A good systemic fungicide at a low concentration is very useful especially if the active ingredient is Imidacloprid (Confidor ®), Malathion or Diazinone.
A good liquid fertiliser for cacti, N1-P2-K2 with microelements13, applied every month14 will ensure balanced growth once the food reserves of the seed are depleted. Make sure the fertiliser is applied at the right concentration because excess nutrients cannot be absorbed by the roots and end up raising the soil pH which leads to root collar rot. I recommend against pricking out plants before time as this can severely damage the delicate vascular bundles of young roots; this is a major cause of plant losses. Resort to this operation only in case of exceptional growth or overcrowding, typical of some species, which however is not detrimental to cacti.
If you have a well ventilated glasshouse with temperatures not exceeding 35°C (95°F), you can leave the propagator inside the building but do not forget to remove the lid and provide some light shade. If you do not have such equipment available, you must move the propagator outdoors and place it in a bright spot; remember to put a frame with plastic or wire mesh on top of it, as previously explained, so as to prevent slugs or lizards, which might be attracted to the heat, from sneaking into the structure and damaging seedlings. Make also sure that adequate shelter is provided against the elements such as strong rain and winds or hail that can easily nullify a few months' work.
The formation of superficial soil crust which tends to rise and come off is undesirable and deleterious to young plants especially during the early stages of their life. If the fine roots have already penetrated into the layer of soil below the crust then you can try to gently crush the latter with the help of a sharp pencil. If, on the contrary, the roots are not yet anchored to the soil below it is advisable to transplant the seedlings. Some growers prevent the formation of crusts by sprinkling a solution of five drops per litre of water of nitric acid (or sulphuric acid); after that they water and rinse the plants. Anyway such crusts should not develop if we allow the soil to dry out well and, most importantly, if we have removed the dust-like particles from the raising mix before sowing. If you notice the presence of green or brown algae on the surface you can spray a solution of copper sulphate (1 gr./l).
Come autumn, if you did not choose to raise your plants in the wintertime, you have to reduce watering until you completely stop by November15, except for some occasional sprinkling if the plants appear to be shrivelling. The delicate genera, namely Melocactus, Discocactus, Alluaudia, Disocactus, Adenium, Jatropha, Euphorbia, Pachypodium, Plumeria, tropical Asclepiadaceae, Bromeliaceae and caudiciforms in general, can be kept growing throughout winter at a temperature of about 20°C (68°F) with some light and sporadic watering although much attention has to be paid to prevent humidity levels from escalating as this can be fatal to young plants. Obviously, you would also need to provide supplementary lighting for a total amount of about 13 hours, using neon tubes positioned at 20 centimetres or so from the seedlings so as to create an artificially extended summer. The first winter is usually the most critical so it is best to keep the most sensitive genera at a temperature of 15°C (59°F) or so. This can be achieved using a propagator or assembling a few wooden planks to build a small-scale glasshouse which will be covered by two layers of plastic film at a distance of 1 cm from one another and kept inside the greenhouse. Cover the bottom with a layer of sand into which you will bury a 50-100 W heating cable controlled by a thermostat then position the structure in the brightest spot. This way young plants will grow and become stronger despite the bad weather. In the unlikely event of one or more plants rotting, most probably because of excess moisture, it is essential to remove and destroy them so as to avoid complications.
In spring we can transplant seedlings into 5/7-cm-diameter pots using the following mix: 1/3 leaf mould; 1/3 garden soil or lapillus (3-4 mm.); 1/3 non-calcareous sand (3-4 mm.). For Mesembryanthemums and Asclepiadaceae raise to 1 part to 2 the amount of sand and reduce to 1 part to 4 the other components. I advise against repotting slow-growing genera like Blossfeldia, Strombocactus, Aztekium, Geohintonia, Parodia during the first year. In order to make transplanting easier it is recommendable to water the pots the day before. Make a hole in the new soil with a pencil and gently introduce the young plant into it; press the soil delicately around the stem until it adheres and finally spray water lightly. After two weeks we can apply a phytostimulant16 to help the plant recover rapidly17.

A few months after germination (from May until August, when stem diameter is about 3 mm.), difficult and slow-growing18 genera can be advantageously grafted onto Pereskiopsis velutina, spathulata, or porteri as well as Echinopsis, which can ensure a faster growth rate but graft take percentage is not excellent.
In the case of grafting onto Pereskiopsis, the latter has to be potted up beforehand using a rich mix then kept in a warm environment and watered regularly so as to maintain active growth. When young plants of Pereskiopsis are 10-20 centimetres tall, they are ready for grafting; cut off their tip where the stem diameter is about 3 to 5 mm with a new razor blade previously sterilised and cleansed of its protective grease coating with some spirit. Subsequently, cut in half the seedling and place the upper portion onto the rootstock in a way that the vascular rings of both scion and stock match, or rather, cross (it is usally necessary to offset the scion on the larger stock to ensure union). Pereskiopsis rootstocks needn't be already rooted when grafted as they can also develop roots afterwards. Grafted plants have to be placed in bright indirect light at about 25°C (77°F) and high humidity which can be ensured introducing the plant in a glass jar with a thin film of water on the bottom then putting the lid back on. After about a week the graft wound should be sealed and the pot can be extracted from the jar, although care must still be taken to always keep the soil moist and avoid direct sunlight. Since this kind of graft is somewhat unsightly, later on you can cut again the Pereskiopsis stock 5 cm below the grafting point then root it straightaway in water. After one or two months when the cutting roots have developed properly we can procede to pot it up burying the stem until the soil slightly touches the scion so that the grafting point is concealed. Another option is regrafting plants which are a few years old onto Echinopsis with a diameter of 2-4 cm in order to accelerate flowering. If, while regrafting our cacti, we leave a portion of the scion with a few areoles onto the old rootstock (Preskiopsis) this will produce new shoots.

A variant of this technique utilizes seedlings of just 1 mm in diameter as scions to be sliced at the hypocotyl level (that is to say above the roots, just below the cotyledons).
It is possible to cut seedlings of about 3-4 mm in half then graft the top part in the conventional way and the bottom part upside down onto the stock (with the roots facing upward): new offsets will develop at the grafting point. After a few days the graft should have taken. It is suitable for tap-rooted plants like Ariocarpus.
When grafting seedlings it is not necessary to apply pressure to ensure contact between stock and scion.

Purchase seeds from companies with proven experience and reliability, sow as often as possible and don't let failure discourage you but try to learn from past mistakes. To succeed you need knowledge, patience, enthusiasm, dedication and in time experience and practice will help you obtain better results. Eventually you will get great satisfaction in return and the chance to grow plants rarely available for sale as well as help reduce the pressure on wild populations of plants and save a considerable amount of money.
Finally, I would like to quote a sentence from one of Steven Brack's articles: 'a cactus flower is always beautiful, but the flower of a cactus you have raised from seed is something wonderful'.
Good luck and don't forget that "ut sementem feceris, ita metes“.19

1- Remember that a high humidity level while promoting germination also contributes to the development of fungal diseases.
2 – See chapter 3.
3 – Avoid using builders' sand; the material should be composed of particles with different diameter and not react when soaked in muriatic acid. The one used to cover the bottom of aquarium tanks is the ideal choice.
4 – The kind of soil termed loam is naturally quite common and easily obtainable. It is free draining, does not harden when dry and cannot be moulded like clay when wet. To some people the term refers to composted grass turves, the layers placed grass to grass, roots to roots.
5 - You will probably need several attempts because the length of time required depends on how hard is the seed coat.
6 – Rain water can be easily collected from the roof via the gutters and downspouts and stored in an opaque container in order to prevent the formation of algae; make sure, however, that it does not contain any harmful substances otherwise you can use either demineralised water or boiled tap water.
7 – Some growers advise using 50% of fine quartz sand and 50% non-fibrous sieved peat; others prefer mixing 8 parts of non-calcareous sand and one part of mature leaf mould.
8 – The soaking times for scarification with 96% sulphuric acid are 10 to 12 minutes for Sclerocactus and 3-4 minutes for Pediocactus respectively. After that seeds must be thoroughly rinsed with water. They can also be scarified mechanically.
9 - Composition: garden soil 25%, sand 50%, pumice 25%, particle size: 1-3 mm.
10- I recommend reading A. Benzoni's article "Una collezione sotto zero" (Cactus & Co. # 2/97).
11 – Read P. Bello's article (Cactus & Co. # 2/97).
12 – A practical alternative to plastic or wire mesh is horticultural fleece (such as Tenax ®) which also ensures a suitable microclimate.
13 – A complete plant nutrient supplement.
14 – If some bone meal has been added to the raising mix, wait six months before feeding plants for the first time. Since it is quite difficult to find a fertiliser with such a low concentration of nutrients you will have to use the right amount of diluted product.
15 – This period may vary depending on latitude. Generally it is best to stop watering when the night temperature is around 8-10°C (46-50°F).
16 – For example amino acid-based products with B-vitamins, auxins etc. to be diluted at one part per thousand.
17 – Some growers advise pricking out seedlings in June and keeping the soil constantly moist until October of the following year.
18 - Ariocarpus, Aztekium, Blossfeldia, Bartschella, Coloradoa, Discocactus, Epithelantha, Escobaria, Geohintonia, Echinocactus polycephalus, xeranthemoides, horizonthalonius, Echinomastus, Lophophora, Mammillaria herrerae, M.egregia, M.humboldtii, M.solisioides, M.saboae, M.haudiana, Navajoa, Obregonia, Pediocactus, Pelecyphora, Porfiria, Rebutia heliosa, R.narvacensis, Sclerocactus, Solisia, Sulcorebutia, Toumeya, Turbinicarpus, Uthaia, Uebelmannia.
19 - "As you sow, so shall you reap " (Cicero)

N.B. All trademarks mentioned belong to their respective owners.

# Article Title Hits
1 The propagator 55775

Our publications

  • Le nostre Pubblicazioni
  • Le nostre Pubblicazioni
  • Le nostre Pubblicazioni
  • Le nostre Pubblicazioni
  • Le nostre Pubblicazioni
  • Le nostre Pubblicazioni
  • Le nostre Pubblicazioni
  • Le nostre Pubblicazioni
  • Le nostre Pubblicazioni
  • Le nostre Pubblicazioni
Add Site to Favorites
Add Page to Favorites

donate one coffee

Support Cactus & Dintorni!