The Nursery (Part 10: Off with their heads! 4 of 5)

This is the fourth part of the post on grafting cacti and will consider whether to keep a plant permanently grafted or alternatively attempt to degraft it.

Once you have a grafted plant you might consider whether to keep it that way or whether to try and do something drastic. If you’re content with your grafted plant, so much the better. However, many collectors find their appearance unattractive and wish to either hide the stock plant or do away with it altogether. Of course, if the purpose of the grafted plant is to produce shoots or seeds it isn’t very important how it looks.

If the stock is low enough, it is often possible to hide it completely in a layer of grit if you have a deep pot. Care must be taken that the grit is of a large enough grain size so as to hold as little moisture as possible. Burying a stock in material that retains moisture for prolonged periods is to invite rot. But this way it’s possible to make a grafted plant appear as if it’s growing on its own roots. If the stock is too tall to do this, it’s possible to cut it off a little below the scion and set it to root. Once it sets roots it can be potted and the stock buried in grit. Beware though, that if the stock is old it might not form new roots easily.

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Fig 15: Obregonia denegrii grafted on a very short stock that has been buried beneath grit. As can be seen, the Obregonia looks as if it grows on its own roots.

However, you might decide that you want to try and have the scion grow on its own roots. Sometimes the decision might be forced on you if e.g. the stock plant dies and you don’t have the option of grafting the scion on something else. Then it’s necessary to try and get the scion to form its own roots.

The practice of separating scion from stock is called degrafting. It isn’t any more difficult than taking a clean knife and cutting off the scion. At least, not in theory. It is certainly tempting to degraft when the scion has grown nice and big, though having the plant form its own roots can be tricky. Some species root only with great difficulty and may wither and dry up before putting out roots. Other species are more accommodating and will put out roots with ease. The scion should be cut off as far down as possible. If enough of the scion remains on the stock it is possible that it will put out shoots that can be removed at a later date. If the cut surface is very large compared to the size of the scion, it is quite likely that it won’t survive. The smaller the cut surface compared to the plant body, the greater the chances that it will survive. Some species might take months to put out roots, and during that time it’s vital that the plant has enough water reserves to last.

Many species are very reluctant to form roots and some species (like Ariocarpus) will never form a proper tuberous root after being degrafted. It is also fairly common to find that the roots formed by a degraft are not as strong as those formed normally by a plant.

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Fig 16: Various degrafted plants. Upper left is Glandulicactus wrightii, Epithelantha bokei, Astrophytum asterias cv. Super Kabuto and Astrophytum capricorne var. crassispinum cv. Taiho. All set root except the A. cv. Taiho. Upper right shows Sclerocactus cloveria ssp. brackei of which all set root. Notice the unusual pink colour of the flesh. The lower image shows Geohintonia mexicana and Echinocactus polycephalus ssp. xeranthemoides of which only one of the Geohintonias has set roots after about 4 months.

In Fig. 17 you can see the various plants I degrafted and then placed in a tray for rooting. They are sitting in a medium consisting of cat litter (this particular cat litter is made of a form of diatomaceous earth and doesn’t clump or change shape when wet), and perlite (the white stuff). The tray was placed on a shelf above my two lamps where they’d be out of direct light but receive a good deal of bottom heat. After a few weeks I started to moist the cat litter and perlite slightly. The cut surface of the degrafts were all treated with root stimulating hormones in powder format, although I am unsure whether this helped at all and it’s not something I feel is needed at all. About 60% of the plants formed roots within 1-2 months, while Geohintonia (of which only one of four formed roots) needed 3-4 months. The Echinocactus, Blossfeldia and some of the Pediocactus failed to form roots.

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Fig 17: Degrafted plants in a tray ready to form roots..

If you really want to degraft a scion, but are worried that it might not survive the process, it’s possible to cut off the top of the scion and either discard it or regraft it (or even just destroy the growing point). The remaining part of it will soon put out new shoots (even if it wouldn’t normally do so), that might in a few months’ time be easy to cut off with only a minimal wound and then set to root. All the while the old scion could continue producing new shoots for you.

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Fig 18: Pediocactus peeblesianus ssp. fickeisenii sprouting profusely after having its head removed for rooting. The cut off head never formed roots, but as can be seen there are plenty of future prospects here for rooting in a few months’ time.

 

The Nursery (Part 10: Off with their heads! 3 of 5)

This is the third part of the post on grafting cacti and will look at why we graft plants.

There are many reasons for grafting cacti. One is to try and save a plant from certain death. Perhaps it is a weak plant that just does not seem willing to grow, or perhaps it’s a rarity or an old beloved family member suffering from some disease or maybe it’s started to rot. In such cases grafting may be the only alternative to throwing the whole thing in the bin.

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Fig 8: This Sulcorebutia gemmae was stagnating for months after germinating. It seemed as though the growing point had been damaged somehow and it didn’t look particularly like surviving for any length of time. I decided to graft it and after only a couple of weeks it started growing. It appears to have found a new growing point as the new growth that can be seen actually broke through the old skin. It has turned into a large and healthy plant now.

Some species are notoriously difficult to keep for any length of time on their own roots, like most members of the North American genera Pediocactus and Sclerocactus. I suspect this has a lot to do with the fact that most collectors place them in a mixed collection with other cacti and give them much the same treatment as those other cacti. Those growers who try to emulate their native climate and growth pattern seem to do much better with them. Be that as it may, most members of these two genera are usually seen grafted because they are hard to keep alive otherwise.

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Fig 9: Sclerocactus mesae-verdae in the foreground, and Pediocactus peeblesianus ssp. fickeisenii in the background. Both of these species are difficult to grow on their own roots.

The third main reason for grafting is to speed up growth. A lot of cacti are painfully slow to grow, a trait often seen in some of the most desirable species. Through grafting it’s possible to achieve greatly enhanced growth rates and flowering ability, as well as not having to take into account some of the species’ fickle nature by letting hardy stock plants deal with all the soil and water. Aztekiums are perhaps the slowest of all the cacti (at least A. ritteri), and not very easy to grow on their own roots either. Through grafting it is possible to grow them tens of times faster and bring them to flowering age years ahead of time. The drawback is that the plants being grafted will often lose their natural appearance.

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Fig 10: On the left is Aztekium ritteri grafted on Eriocereus jusbertii, while on the right is Mammillaria luethyi grafted on Pereskiopsis. Aztekium ritteri isn’t the easiest plant to grow on its own roots, and is painfully slow to boot. Because of this it is most often seen grafted. Mammillaria luethyi isn’t particularly difficult, but is most often seen grafted primarily because it is a cryptocarp (it hides its fruits within the plant body for years) which means that seeds are seldom available, so the easiest way to propagate it is through grafting cuttings such as the above.

The fact that grafted plants so often lose their natural appearance is probably the biggest drawback for me personally, as I am not a particular fan of how some species turn out looking when grafted. Some species look fine when grafted and don’t deviate much from how they’d look on their own roots, but some species (like Aztekium) can almost look like different species altogether compared to their brethren growing on own roots. There is also a sense of achievement in successfully growing some of the more difficult species that just isn’t found when grafting them.

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Fig 11: The two images show the same specimen of Aztekium hintonii. As can be clearly seen, it grows vigorously and flowers profusely, but its appearance is not quite natural.

As touched upon above, achieving flower production much sooner than would otherwise be possible is an important reason for grafting. Pereskiopsis is perhaps the most widely used genus for grafting seedling cacti. Its stems are thin and suitable for very small plants, and its growth is simply explosive. I’ve never tried growing Pereskiopsis to their full potential, but if given enough heat and light they can probably enjoy almost continuous wet/moist soil which would be the death of most ordinary cacti. Properly grafted on a sizeable Pereskiopsis 10-15 cm high with full green leaves in optimal conditions, a seedling no more than 2 weeks old can probably achieve flowering age within a matter of 2-3 months at a size it might otherwise need half a dozen growing seasons to achieve on its own roots. I’ve never achieved anything close to that personally, but then I’ve never grafted on properly sized Pereskiopsis in ideal condition enjoying near limitless quantities of water.

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Fig 12: Lophophora alberto-vojtechii grafted on Pereskiopsis. The plant was grafted around 6 months after germination as it didn’t grow particularly well. 4 months after being grafted, the first bud appeared (left). The middle image shows the flower, and the right image shows the plant ca. 1 year after originally grafting it. It’s the size of a 2€ coin which is probably about as big as the plant would ever get in nature.

Achieving a much more rapid flower production than would otherwise be possible is very beneficial when trying to set seed on rare species. Aztekium ritteri is a fairly common species in seed lists, but if you want to get seeds on plants growing on their own roots, you might have to wait up to a decade. Grafted, the same species might oblige within a year of being sown. Grafted plants generally produce more flowers and are usually able to bear more fruit to maturity. In some Asian countries (particularly Japan and Thailand) they’ve perfected the art of grafting, and some of the master growers of Astrophytum can raise several generations in a couple of years with the purpose of hunting for new and rare hybrids.

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Fig 13: Sped up flower production on Lophophora fricii and L. koehresii. None of these plants are more than a year old.

Another reason to graft is if you sow seed and get a weirdo seedling coming up. Perhaps it is fasciated (crested), monstrose (abnormal growth pattern), variegated (with parts of the body having less chlorophyll), or abnormally proliferous (where every areole produces a new shoot), or perhaps it is a particularly striking hybrid. In such cases you might want to hang onto it. However, such plants are often not as strong as their normal brothers and sisters, so grafting them is a good way to ensure they stay alive. Such plants hold a great fascination for some growers who are willing to pay a lot of money for good specimens. Some plants lack chlorophyll altogether, like the well known red or yellow grafts that are often seen in supermarkets (Gymnocalycium mihanovichii and Chamaeocereus hybrids respectively). These plants wouldn’t survive on their own (seeing as they lack chlorophyll) and must be grafted to survive. It is even possible to make something akin to a decoration by grafting several different plants on one stock plant with many shoots.

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Fig 14: Variegated Lophophora diffusa. This plant might not have survived on its own roots for very long, and even if it had it would likely never have become a “strong” plant.

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Fig 15: Cereus peruvianus ‘Monstrosus’ has a growth habit where the ribs form in an irregular manner. This plant isn’t grafted though, and manages perfectly fine on its own roots.

The Nursery (Part 10: Off with their heads! 2 of 5)

This is the second part of the post on grafting cacti and will look into more detail about the technical bit of actually grafting a cactus.

The one single thing about grafting that is of utmost importance is cleanliness. If you set to with a rusty old knife held in dirty fingers, you’re asking for trouble. Clean tools should be used, and they should ideally be disinfected at every turn (at least after every major operation) with rubbing alcohol or some other disinfectant that won’t leave traces. As with clean tools, it is naturally also vital that the cut surfaces are both clean and free of any rot, sickness or debris. Your working area should be clean and somewhere out of the sun and the elements.

For cutting larger plants I prefer either a sharp knife with a comfortable handle or a snap-off knife. For seedlings I think razor blades work best. Depending on what kind of plants you’re working with, some form of protection might be beneficial. When working with Pereskiopsis I like to use a sheet of aluminium foil folded several times to make a sort of finger-protection-device allowing me to hold the plants without having to suffer their devilish spines. A good pair of tweezers will often come in handy too. Rubber bands are handy when it comes to larger grafts to push the scion and stock together if the scion is of the globose kind and the stock plant isn’t too tall. It’s easy to push the scion off the stock with rubber bands so it’s important to be careful when using them. Weights of different kinds can also be used to put pressure on the scion so that it properly fuses together with the stock.

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Fig 4: Various tools for grafting.

When grafting plants that have started rotting (in an attempt to save them), it is necessary to cut away all the diseased or rotting parts of the scion, even if it means cutting it so short that grafting becomes almost an act of futility. Almost all cacti are a nice and healthy green inside (the flesh of some species has a more yellowish or reddish hue), so any traces of black/brown or discoloured spots or marks visible on the cut surface means you have to continue cutting. And for each cut it is necessary to disinfect the cutting tool so as not to unwittingly spread infected material to healthy tissue. The cutting tool should be very sharp and, if possible, the cut should be made in one or two smooth motions and not in a sawing fashion. It’s also helpful if the cut is as straight as possible.

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Fig 5: Seedling grafts on Pereskiopsis. Seedlings can easily be grafted from around 2 weeks old.

When grafting seedlings it is easiest to use a razor blade. The seedling can be held between your fingers while carefully slicing it in one motion. The top of the seedling will be sitting on the razor blade and can easily be pushed or nudged over to the surface of the stock plant. Once placed it should be gently rotated or wiggled a bit to remove any potential air bubbles trapped underneath, and care must be taken to place the scion so that it is in contact with some of the vascular bundles of the stock. No weights are usually needed to provide pressure on the seedling against the stock, as the sticky sap of the stock will be enough to keep it in place.

When grafting anything larger than seedlings or very small plants it is useful to shape the surface of the stock a little bit before grafting (see Fig 6). If areoles are left on the stock plant right by the cut surface, it can lead to shoots forming from them that might eventually push the scion off. Cutting away the outermost sides of the stock in an angular fashion to remove areoles will help the union be successful.

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Fig 6: Image 1 shows an Eriocereus jusbertii shoot (a common stock plant). Image 2 shows the top of the Eriocereus removed. Image 3 shows angular cutting of the sides to remove the topmost areoles. Image 4 shows the top and bottom of the plant “ready for grafting”. On image 4 on the “stock”, notice the tiny bit of debris at the centre of the plant. This is something that would have to be removed before grafting. Image 5 shows the finished “graft”.

It’s extremely important that none of the cut surfaces dry out when grafting. If they do, a new cut has to be made. The stock should be cut first and, unless it’s a seedling graft which is very quick, to protect the cut surface either the top that was cut off should be put back in place until the scion is ready or a small slice of the stock should be cut and placed on top of the wound. Then the scion is cut and quickly placed on the stock (if a small slice of the stock was placed to protect the wound, be sure to remember to remove it). The scion should be lightly pushed down on the cut surface of the scion with the fingers and wiggled around a little bit to remove any potential air bubbles that might be trapped between scion and stock.

The scion gets its nutrients from the vascular bundles of the stock plant. It is therefore necessary that the vascular bundles of both parties are aligned such that there is an overlap. If they don’t align very well it is likely that the growth of the scion will be poor, which is why it is important that particularly the scion does not greatly outsize the stock . When grafting seedlings or plants so small that they do not cover the stock’s vascular bundles, they should be aligned so that they sit astride a section of the stock’s vascular bundles. This will allow them to receive sufficient nutrition from the stock. When grafting seedlings on thin Pereskiopsis stock this is usually nothing to worry about.

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Fig 7: In this close-up of image 3 in Figure 6 above, it’s easier to see the different parts of the plant’s internal structure (simplified). The epidermis is the outer skin. Immediately inside is the cortex which constitutes the largest part of the flesh in cacti. Then comes the vascular bundles which can be seen above as a ring separating the cortex and the pith. The pith is the circular centre of the plant which is somewhat denser than the flesh of the cortex. In some species, like most opuntias, the pith and vascular bundles form an oval instead of a circle. When grafting small plants or seedlings on Opuntia, it is often possible to graft several plants on the same cut surface because of this.

After the scion has been successfully placed on the stock, it should be weighted down (unless it’s a seedling) either with weights or e.g. with rubber bands over the scion and under the pot. Be sure not to squeeze the scion to death and, if using rubber bands, take care not to push the scion off the stock through poor placing of the rubber band (which unfortunately is all too easy to do). With smaller scions it is often a bit more tricky to use rubber bands, and some form of weights might be better. E.g. a small coin or thin sheet of glass or something similar might be placed on top of it, balanced against something else. It’s also possible to wrap cling film around the scion and stock to provide both a moist environment as well as some pressure.

Once the graft has been made the happy couple should be place out of direct sunlight and preferably in a somewhat humid area. A few days under plastic or in a propagator, or on the lower shelf of the greenhouse should suffice to seal the deal. Grafted seedlings benefit from a slightly more humid environment in the first few days to secure the union. If the graft is successful, the scion and the stock will have fused together within 1-2 weeks of grafting and growth should be visible within a few weeks (less with seedlings). At this point the pair should still be treated gingerly, as it’s only after a couple of weeks that the union is so secure that a mere bump or something similar won’t easily dislodge the scion.

The Nursery (Part 10: Off with their heads! 1 of 5)

Taking inspiration from a recent comment one of my readers made about grafting, I thought I’d write a post about it. In fact, I’ll write five. Some of the posts I’ve written before have become far too big so, instead of writing one monster post, this time I thought I’d split it up in more manageable parts. The first three parts will be about the how and why of grafting, the fourth part will be about the choice of either degrafting or keeping a plant permanently grafted, while the last part will deal with some of the different grafting stocks that are in use.

Grafting cacti is usually very easy. The family is uncommon among plants in that almost every cactus can easily be grafted on members of only distantly related genera. I suppose the genus Pereskia is an exception to this, being hardly succulent at all, although I’ve never actually tried grafting them. While it might technically be possible to graft any cactus on any other cactus, not all cacti are suitable as stock plants.

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Fig 1: Various grafted plants and some different stocks.

With grafting, the two main players are the stock and the scion. The stock is what one uses to graft on, while the scion is the bit that’s being grafted. This will usually involve the stock losing its head, while the scion is separated from its lower body. The scion is placed atop the stock and, once the two parts fuse together, a more or less happy marriage ensues. For as long as the union lasts, the scion will draw all the nutrients it needs from the stock. The stock itself should be in perfect health, it shouldn’t be too big or too small with regards to the scion, and the graft should only be made on new and healthy tissue.

The most straightforward and common way to graft cacti is to cut both stock and scion “horizontally” across the body so that the scion will fit nicely on top of the stock. As mentioned in the previous post, it’s important that there isn’t a huge size difference between the two parts. However, some cacti that grow long thin (or thin-ish) shoots that might be difficult to graft “standing up”, can be cut laterally along the body and then pressed down on the horizontal surface of the stock. Areoles on the scion will then go on to produce shoots. The members of the genus Echinocereus that were formerly known as Wilcoxia are perhaps candidates for this method.

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Fig 2: Grafted plants on Pereskiopsis and Selenicereus.

It’s also possible to graft tubercles of some species. I have attempted to do this with an Ariocarpus trigonus that suddenly decided to head for the great desert in the sky. A few healthy tubercles were left, but not enough to graft normally, so I decided to try and graft a couple of the tubercles. Only one is still alive (after three years) although it hasn’t done much except not die. The idea is that the tubercle will be able to sprout a new growing point from it’s base from which the plant will be able to regrow and form a new normal looking Ariocarpus. Apart from Ariocarpus, I’ve read that certain mammillarias and some members of other genera are able to regrow from a single tubercle in this way. It remains to be seen whether my attempt will ultimately prove successful.

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Fig 3: Ariocarpus trigonus tubercle grafted on Opuntia compressa.

The top that was removed from the stock may be set to root or be discarded. To avoid the possibility of virus infections it is recommended that stocks be grown from seed and only used once, i.e. no parts of it are reused. As far as I know I have never had any trouble with viruses on stock plants, but then virus infections are a very little studied phenomenon in cacti. It may be more widespread than we think, or the danger of it may be very exaggerated. I have often used stock plants several times and often taken cuttings from older stock plants to use. And for some stock plants, such as Pereskiopsis, seed is hardly, if ever, available. The remains of the scion may also be left to continue to grow and set new shoots unless it’s a rescue job, of course.

It may seem irreverent to cut and slice our plants open, but a lot can be learned from it. It can be fun to try and see how quickly you can manage to grow a species, or you might be interested in trying out different stock plants to see which suits best for a particular species. Grafting can allow you to witness your plants flowering years ahead of time, or let you save just that one very special plant that has begun to rot. Grafting can be a method to grow plants you might not otherwise be able to grow on their own roots, or you might simply find grafted plants attractive. Whatever the reason for grafting, it is certainly a worthwhile practice to know and understand.

Denmoza rhodacantha

Denmoza is a South American genus consisting of one accepted species: D. rhodacantha. Another species has been described as D. erythrocephala, but it is generally not accepted as a “good” species. The species grows in Argentina in the region of Mendoza, of which the genus name is an anagram.

Red-spined (normal) form of D. rhodacantha in bud.

Brownish-red-spined (normal) form of D. rhodacantha in bud.

In habitat there are specimens reaching heights of up to 3 meters according to Hunt et.al. in The New Cactus Lexicon. However, the “normal” description of D. rhodacantha calls for a species globular in shape, only elongating towards a slight columnar shape in old age. The plants I have are probably around 25 years old and very much globular at approximately 15-20 cm in diameter and about the same in height.

Close-up of the flower. It produces a great amount of pollen that is very shaken loose, which may suggest the flowers are wind pollinated in habitat.

Close-up of the flower. The stamens produce a great amount of pollen that is very easily shaken loose, which could possibly suggest the flowers are wind pollinated in habitat.

Described in 1922 by Britton and Rose, the genus Denmoza has later been included both in Cleistocactus and Oreocereus. As can be seen from the flowers on these plants and the specimen of Oreocereus trollii described in a previous post, there are some clear similarities. Some more recent research suggests the genus is more closely related to the genus Acanthocalycium and certain members of Echinopsis s.s. (“sensu stricto”, as in the strict or narrow view of Echinopsis). It is also possible that it arose in the distant past as an intergeneric hybrid between Echinopsis and Oreocereus, as suggested in J. Lodé’s The Taxonomy of the Cactaceae. 

Yellow-spined form.

Yellow-spined form.

The usual descriptions of the species calls for brownish red spines, which certainly doesn’t fit the yellow-spined form I have. The spines on that particular specimen are also slightly stronger than on the brownish-red-spined form. I think they are both very attractive forms and although they take a long time to start flowering (probably at least 15-20 years), they are well worth growing.

Here the stamens and pistil are just emerging. The yellow-spined form is particularly handsome, especially when contrasted with the attractive red of the flowers.

Here the stamens and pistil are just emerging. The yellow-spined form is particularly handsome, especially when contrasted with the attractive red of the flowers.

I cross-pollinated the two plants as they happened to flower at the same time and intend to sow some of the seeds that resulted from the happy union. I certainly hope the yellow-spined form will show up in some of the seedlings.

It is quite easy to grow and fairly tolerant of adverse conditions. It’s hardy down to at least -5°C and probably a good deal more for short periods. A well-drained porous soil with perhaps 30% organic material will give good healthy specimens.

Rimacactus laui

This species was discovered in 1971 by Alfred Lau, in a location south of Tocopilla, Chile. It took some time before it was officially described because it shares many characteristics with both Copiapoa and Eriosyce s.l. (s.l. meaning “sensu lato”, as in the expanded view of that genus), while at the same time possessing many particular characteristics other members of those genera do not. In the nineties it was included in the genus Eriosyce s.l., although some felt it belonged in Copiapoa, while others felt the genus Islaya (included in the sensu lato version of Eriosyce) was the best fit. Roy Mottram felt the species was too distinct to belong in Eriosyce, and erected the genus Rimacactus for it in 2001. Later phylogenetic molecular studies have shown this to be the most correct option, as the species is not closely related to Eriosyce. The same studies show that it is most closely related to Yavia (another monotypic genus) and Neowerdermannia (a genus with two species).

It is an attractive species with white needle like spines on a greenish-brown body, and with copious amounts of wool. There is, however, a very great difference between plants in habitat and grafted plants in cultivation. The plant is often grafted because it is fairly difficult on its own roots, being particularly vulnerable to overwatering. The upside of grafting is that it flowers easily and willingly, while also developing a lot of attractive wool. On the other hand it does not particularly resemble habitat plants when grafted.

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Rimacactus laui in bud.

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Here you can see the root stock clearly. The plant is around 5 cm in diameter.

I sowed some 10 seeds 18 months ago and two germinated. They grew very slowly and as seeds of this species are usually quite rare I decided to graft the two seedlings in order to try and produce seeds of my own in the future. Only one of the grafts were successful however, but in exchange it has grown very well and has now flowered just a little over a year after being grafted. The stock plant is Pereskiopsis diguetii which is an excellent stock plant for seedlings and will greatly accelerate growth.

The petals are a nice shade of yellow, while the sepals contrast well with an attractive brownish-red colour. The flowers last a good deal longer than in most cacti. The flowers also contrast nicely with all the white wool.

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In habitat the plant will probably not grow much bigger than this, and will not develop as much wool.

Close-up of the flower.

Close-up of the flower.

I am going to sow more seeds of this species soon and try to grow them on their own roots. The species will probably do best in a completely inorganic mixture with somewhat infrequent watering.

A change of scenery

Previously this blog was hosted by Blogger, but I decided it was time for a change. The old address (www.living-rocks.blogspot.com) will no longer be used. I couldn’t keep the old title of the blog as that particular domain name was already taken. Therefore I had to come up with a new name. I am quite happy with the name and site change and hope it will spur me on to more frequent updates!

-Karl

Oreocereus trollii

Just a couple of weeks ago I noticed a bud developing on an Oreocereus trollii in the greenhouse. It’s always a little extra exciting when columnar species flower because they usually take quite a lot longer to reach flowering age than the globular ones, and this species had never flowered before. I sadly missed the show, though my father was there to document it. I’m not quite sure how old it is, though I’d venture a guess at around 15-20 years perhaps, and it’s probably around 25 cm tall.

Oreocereus are found in the Andes of Peru, Bolivia, Chile and Argentina at altitudes between ca. 1000 – 4000 m a.s.l. O. trollii is found in southern Bolivia and northern Argentina at around 4000 m a.s.l. The great amount of hair on the plant is there to protect it against wind and cold. This particular species doesn’t become any taller than between 50-100 cm. It’s a testament to the adaptability of cacti that this species can thrive and flower at sea level in Norway (almost 60°N) when its habitat is near 20°S at 4000 m a.s.l. in the Andes, approximately 11 000 km away!

Oreocereus trollii with its first flower. 

Close-up of the flower. I quite like the purple anthers.
Another close-up of the flower. The combination of the flower colour, the yellow spines and the white hairs is quite attractive.

Update

It’s been a long time now since my last post. My apologies to those of you who have been stopping by over the past few months hoping for updates! I will try to publish more often in the future, and start with a pictorial update of some more flowering over the past few months. All the plants shown below are between 16-20 months old at the time the pictures were taken.

First off, my Pseudolithos cubiformis and P. mccoyi have simply not stopped flowering over the past year. Whenever one plant has begun flowering another has set buds, and so on. Thankfully the smell (or stench) of rotten meat from the flowers isn’t very noticeable unless you get your nose up close to them. I still haven’t been able to pollinate any of the flowers, but with summer now arrived I hope that some flies might come along and help out.

Pseudolithos cubiformis with a bunch of buds ready to open.

P. cubiformis with the flowers just starting to open. 

P. cubiformis with all the flowers open. They stay open for about two days.

Two P. cubiformis in flower. Unfortunately I don’t know how to pollinate them without the help of flies.

Pseudolithos mccoyi in flower. The flowers are quite a lot smaller than P. cubiformis and the structure looks very different (at least superficially). The flowers of this species don’t really smell much.

Close-up of a flower of P. mccoyi. The flower is approximately 5 mm wide.

I’ve also had a bit more flowering from my Adenium, with A. multiflorum continuing to flower, but now also joined by one A. obesum. At this age all of A. multiflorum, A. obesum and A. arabicum look rather similar superficially, with only some small differences in leaf shape. The flower colour between A. multiflorum and A. obesum was very different, though I’m not sure how variable the flower colour is or whether it stays true to the species. I am not even sure whether the above three are really separate species or just forms of one variable species.

Adenium multiflorum with pretty pink and white flowers.

A. multiflorum flower at very close range.

Adenium obesum with flowers that look more or less identical in structure to A. multiflorum, only with a different flower colour. The deep pinkish-red colour is very attractive, though.

A zoomed out picture of the A. obesum pictured above.

A few months ago Lithops werneri produced a flower, so far being the only species of Lithops that have decided to start doing so. Two plants of this species have flowered now, and both kept the flowers open for over a week.

Lithops werneri with a tall flower tube.

Close-up of the flower of L. werneri, showing a pretty yellow colour.

My Turbinicarpus longispinus, much like the Pseudolithos, have simply kept on flowering continuously for a year now (also see previous post on this species). I am surprised that they aren’t taking a break. I suppose my conditions with the artificial light and regular watering might simply be confusing them into believing that they’re in a never ending flowering season. It is also a bit surprising that this species is so ready to flower, while other Turbinicarpus species I have that are just as old and by their physical appearance should be ready to flower, have not yet done so. I expect the reason must simply be that some species of the genus require a (probably cooler) resting period while others don’t need this in order to flower.

Turbinicarpus longispinus in flower.

The last pictures in this update are of two new Mammillaria species flowering for the first time. Some decades ago these two species were thought to belong to a different genus than Mammillaria and the genus Solisia was erected for the two of them. I’m not really sure exactly why this was done and especially not why these two species were thought to deserve their own genus. Apart from some physical similarities (particularly spination) I don’t really see a close resemblance between them, and the genus Solisia was abandoned a long time ago.

Mammillaria solisioides showing both flower and buds. The flower is approximately 3 cm wide.

Close-up of the flower of M. solisioides. The heat from the lamps has caused the petals of this flower to bend backwards.

Mammillaria pectinifera with a large bud. So far this is the only plant of this species that has flowered.

M. pectinifera with the flower just opened. The colour is a very pretty and delicate shade of pinkish-white with a slightly darker mid-stripe on the petals.

M. pectinifera with the flower wide open. The flower is approximately 2,5 cm wide.

That’s it for this post. Hopefully there’ll be some more flowering in the nursery over the coming months for me to show, but the next post will be about plants in my greenhouse.

The Nursery (Part 9: Soil components)

In this post I will expand upon Part 4 of this series and go into more detail about the various soil components I currently use (to a larger or lesser degree) for my cacti and succulents. I will first discuss organic and inorganic soil, and then go through the different soil components I use to a larger and lesser degree.

Organic or inorganic soil

I prefer an inorganic soil to an organic based one for most of my plants when they are past the seedling stage. There are several reasons for this. One is that most of the species I’m currently growing (and most of those I like the best) are susceptible to overwatering and thus require a very free draining soil which doesn’t retain moisture for a long time. This is easier to achieve with an inorganic soil than an organic one. Another is that inorganic soils reduce or eliminate the risk of several pests such as the sciara fly and (I believe) the root mealy bug. A further reason is that an inorganic soil with little or no freely available nitrogen will more easily induce a compact form of growth, compared to organic based soils in which plants more easily stretch.

Yet another reason is that with an inorganic soil it is possible to grow the plants completely without the use of fertiliser and have them look very natural (approximating the “natural” look in habitat), though I am not currently growing any of my plants without fertiliser. If one chooses to grow the plants without fertiliser, one must take care to choose a soil mix that contains all the nutrients the plants need. In the journal Acta Succulenta which is a free online journal available for download from their website Acta Succulenta, there is a very interesting article in the second publication of this year discussing a method of growing cacti they call WIG (Wild Grown). A similar method is discussed at length in a Xerophilia Magazine special edition called “The Rock Eaters”, which is also an excellent guide to the use of inorganic soils. It is available for download from their homepage Xerophilia. Personally I find plants grown this way to look more beautiful than plants seen grown in organic soils which tend to become more elongated or bloated – though this also depends on the species.

Example of an inorganic soil.

A very interesting article which appeared on the BBC a few years ago ago reveals how (many or most?) cacti live in symbiosis with bacteria in the soil that break down rocks around the roots allowing them to absorb nutrients that wouldn’t otherwise be available. It also shows how the plants incorporate these bacteria into their seeds. This explains how it is possible to achieve excellent results by growing cacti in 100% inorganic soil without using fertiliser.

I grow almost all my current North American species in an inorganic soil. Only about one tray with North American species are potted in an organic based soil in order to compare their growth with similar species grown in an inorganic soil. So far the plants grown in the inorganic soil seem to do better and stay more compact. Since they all share the same level of light and amount and frequency of waterings, as well as the amount of fertiliser given and soil volume, and they’re all the same age, I think the only thing of importance that separates them is the soil composition. The ones in an organic based soil (particularly Epithelantha and Mammillaria) all tend to elongate and become more bloated compared to those grown in an inorganic soil.

I do grow some species in an organic based soil because I feel they do better with some organic matter. Chiefly among those are the South American species such as Rebutia, Sulcorebutia, Lobivia and Frailea (and any other South American species not growing in particularly arid environments). I kept my Frailea asterioides in an inorganic soil for some time, but they grew only very slowly. I keep my Discocactus horstii in an inorganic soil, however, and they are all growing very well – though in nature they grow in almost pure quartzite sand and gravel.

Example of an organic soil. This one is based on coir.

What you decide to grow your plants in will depend on your own beliefs and ideas on which soil is the best, which soil components are readily available where you live, the cost of the various soil components, and the types of species you like to grow. There is no answer to which soil is the best and almost every book on cacti will offer different advice. One should also keep in mind that cacti grown in pots are wholly removed from their natural habitat and must be treated accordingly. Adaptations must be made to account for a (probably) much reduced living space for the roots, a different fungal and bacterial flora in the soil, and of course usually a vastly different climate.

Just like seeds will readily germinate in commercial cactus soil mix, so will most species grow happily in the same mixes. They will be more prone to rotting though. If using such a mix I would definitely recommend adding extra grit such as perlite or gravel to increase the drainage.

Soil components

There are a plethora of different soil components available, and the following simply represent the various things I have personally used and have experience with. As I said above, there is no “correct” soil and one grower will have positive experiences with one soil while another will not. 

Peat

The only soil component that I would actively advice against is peat. I discussed my reasons for this in Part 4, but to summarise very shortly: peat takes a long time to dry out and when it has first dried out it is very difficult to re-wet; it is a magnet for the sciara fly, and the root mealy bug too, I believe; it quickly becomes compacted and reduces the amount of air available to the roots; it clings to the roots so that during repotting it is difficult to remove all of it without damaging the roots; it often leads to a less developed root system; it contains a high amount of nitrogen (and is often augmented with fertiliser high in nitrogen) which can lead to root burn and also abnormal growth; and finally it is not very environmentally friendly as the extraction of it destroys natural habitats for many species and can take centuries or millennia to reform, as well as leading to increased greenhouse gas emissions through the release of CO2 and MH4.
The only reason to use peat in my opinion is if you are just starting out with the hobby and only wish to keep a few species in the window sill, or if alternatives are very hard to come by.

Compost

I’m only mentioning this very quickly as it is probably the most commonly used ingredient in organic based soils. I do not use it myself because I have not found a good manufacturer yet. In Norway there is as good as a monopoly when it comes to garden centres, and by far the biggest (and almost only) garden centre does, to the best of my knowledge, not sell composts – at least not any that are useful for growing cacti. Some local garden centres or plant schools may still sell quality composts though, again, I have not really come across any. A good quality compost is probably the best ingredient to use in an organic based soil because it provides most of the nutrients the plants need which reduces the need for fertiliser.

Coir

Coir is fibres extracted from the husks of coconuts. It is a far better alternative than peat for organic soil mixes. Among the advantages are that it is naturally free of bacteria and fungi, it is easily rewettable after drying out, it doesn’t compact like peat, it doesn’t cling to the roots, and it rarely clumps together (and if so the clumps are very easily crumbled apart). Among the disadvantages is its lack of nutrients which means a greater need for fertiliser, its light weight (which in some cases can be an advantage, though), and the fact that it is poor in calcium and magnesium. A lack of magnesium is a problem for all plants, but a lack of calcium is also especially negative for most cacti. This can be remedied by adding calcium and magnesium through fertiliser or by adding rocks such as dolomite (containing both magnesium and calcium) directly to the soil. Dolomite is an excellent rock to add to the soil for most cacti regardless of whether you use coir or not.

Finally it is also important to check whether the coir you have has had fertiliser added to it. As with peat mixes, I believe fertiliser is often added to bags of coir too.

Coir. A very good substitute for peat.

Leca

Leca (light expanded clay aggregate) is produced artificially by heating clay at very high temperatures. It improves drainage and with it’s honeycomb structure it also retains a lot of air. Leca usually comes in sizes too large to be of much use in small to medium size pots. In large or very large pots it would be useful as a soil additive. For smaller pot sizes the main use would be to increase drainage by placing a shallow layer of leca pebbles in the bottom of the pot. It can also be useful as top dressing in larger pots, though it should ideally be washed before use to remove the dust coating the pebbles.
Leca pebbles are usually too large to be of much use in small and medium size pots.

Expanded shale

As with leca, this product has also been fired at high temperatures in order to make it expand. Shale is a naturally finely laminated (fissile) sedimentary rock consisting of clay and silt size particles. When it expands this structure leads to the rock becoming very porous. It has similar soil improving characteristics as leca, only more suitable for small to medium size pots. I have used two sizes, a 4-8 mm grain size and a 1-3 mm grain size. For smaller pots the larger grain size is still a little on the big side, but the smaller grain size is ideal. Similarly to leca it doesn’t lose shape or disintegrate. The larger size expanded shale is also useful as a top dressing.
Expanded shale, grain size 4-8 mm.

Expanded shale, grain size 1-3 mm.

Crushed lava

This soil additive is, as the heading says, crushed lava. It is naturally a very porous rock increasing drainage and improving soil texture. It is heavier than artificially expanded materials and so adds a bit of weight to pots (which might otherwise become a bit light if a lot of material like coir or perlite is used). The grain size I have used is 2-8 mm, which is on the large side for small pots. It is also useful as a top dressing, though its sharp edges may cut or scrape the plant as it grows and expands.
Crushed lava, grain size 2-8 mm. 

Pumice

Pumice is a highly porous volcanic rock and a very good soil additive. Much like the materials mentioned above, it improves soil drainage and structure, as well as retaining water and air which is slowly made available for the roots. It comes in many different sizes, though – like the above materials – the larger sizes are less suitable for small and medium pots.
Pumice, grain size 5-15 mm.

Pumice, grain size 2-5 mm.

Zeolite

Zeolite is a very porous aluminosilicate mineral. It occurs naturally but can also be produced artificially. I use a natural form which comes in gravel size. It is widely used as an adsorbant in various industries. It absorbs a lot of water and, due to its molecular structure, can retain various elements. The idea behind using it in the soil is that its capacity to adsorb and retain elements will lead to these becoming available to the roots as the water stored in the mineral is released as the soil dries. However, I am uncertain if it actually works as intended in the soil. To me it seems like the zeolite doesn’t really leach these “trapped” nutritional elements as the water drains from it, but rather builds them up to the extant that salts crystallize on the surface. If this is, in fact, the case then its usefulness is very limited since its other chief value of retaining water is achieved by lots of other materials. One other use would be top dressing for certain plants, as its green colour is very nice.
Zeolite, grain size ca. 5-10 mm.

Crushed terracotta

This is another useful material to add to soil. Gravel size it acts to improve drainage and soil structure, as well as absorbing water which is then slowly released into the soil as it dries. In finer sizes it is useful as top dressing and soil component for seedlings. Made from clay, there are also a lot of various minerals available for the roots to extract.

Crushed terracotta, grain size ca. 4-6 mm.

Crushed terracotta, grain size 0-2 mm.

Clay

Clay can be a very useful additive in small components. Because of its very fine grain size it can reduce drainage in the soil and retain too much water if there is too much clay in the soil. It contains a large amount of elements however, and in small amounts it is a useful additive. 
As can be seen on the picture, there are many large clumps of clay. These can be problematic in the soil as they can create areas where more water than desirable is accumulated.

Akadama

Akadama is the name of clay pebbles that occur naturally in Japan. They are widely used in the bonzai industry because of their ability to absorb a lot of water and retain their structure as they dry, and repeat the process over and over. It improves drainage and aeration in the soil, as well as providing a lot of nutrients. It is an expensive product, however.
Akadama clay pebbles, grain size ca. 2-4 mm.

Sand

Sand is a much used soil additive. Added to organic mixes it helps improve drainage and soil structure. However, in inorganic soils I believe it has a tendency to move around and cling together with other sand particles creating zones with more sand, which leads to reduced drainage. In many cases it may be better to use either coarse sand or fine gravel which will do the same job as sand, but not potentially impact negatively on drainage.
Sieved filter sand, grain size 1-2 mm. 

Gravel

Gravel, particularly as crushed rock, is a useful soil additive to improve drainage and structure. It is probably the cheapest inorganic material too (along with sand). If you want to grow in a completely inorganic soil it is perfectly possible to do so by combining gravel from different rocks and minerals in the soil to provide all the nutrients the plants need. For seedlings and in small pots it may be of less value as smaller size material will probably be better, but in medium to large pots it is an excellent additive. It is also excellent as top dressing.
Crushed phyllite, grain size ca. 5-10 mm. 

Diatomaceous earth

This is a light, porous sedimentary rock consisting of fossilised remains of diatoms. It consists mainly of silica and some aluminium. It comes in a range of grain sizes from dust all the way up to gravel size, and has a wide variety of uses. It retains water and nutrients which is slowly released as the soil dries. I don’t have a lot of experience with this material but it seems a good soil additive.
Diatomaceous earth, grain size 1-3 mm.

Perlite

This is an extremely light volcanic material that occurs naturally, but is used only after being processed by firing it at very high temperatures, expanding the material greatly. It helps improve drainage and soil structure, while having a fairly low water retention capacity. It is a very useful material and fairly cheap, however its low weight can be an issue as the perlite particles will very easily float to the surface of the pot – especially if watered from above.
Perlite, grain size ca. 3-6 mm.

Vermiculite

Vermiculite is a naturally occurring siliceous mineral that expands greatly when fired – like perlite. After being processed in this way it becomes a very useful soil additive to improve drainage, for retaining water and nutrients, and for increasing soil structure. While also extremely light, it doesn’t float to the surface like perlite.
Vermiculite, grain size ca. 3-8 mm.

Mineral magic

This material is something I don’t quite know the usefulness of as a soil additive. It is a dust-like yellowish material that is supposed to contain 65 different minerals and 60 % of the content is supposed to be water soluble silicates. Spread around the top of the soil it is supposed to prevent algae and fungi growth, while as a foliar spray it is supposed to act as an insecticide. As a soil additive I don’t know whether it is a very useful substance considering all the minerals it supposedly contains, or whether the dust size grains merely leads to reduced drainage. It is supposed to increase the cation exchange rate in the soil which should lead to more nutrients being available for the roots. I add a little bit of it in my soil mixes. If it does what it claims it should be a useful additive. 
Mineral magic. With a saguaro (Carnegiea gigantea) pictured on the label it surely can’t hurt to add to the soil!

Conclusion

In the end, it isn’t really critical to use one particular soil component or the other. I have tried out quite a few because I’ve been curious about how they work, but many of the materials talked about above do much the same thing. The important part about soil is that it should be well drained and have a good structure with plenty of air. Whether this is accomplished through an inorganic soil or an organic based one isn’t that important. The amount of the various materials is only really important when it comes to growing plants without the use of fertiliser at all, since then one must strike the right balance in the soil between the various components so that all essential and beneficial nutrients are provided.
The size of the collection and which materials are most easily (and cheaply) available will usually be the deciding factors on which soil components to use.