Planting columnar cacti and euphorbias

Today something about (re-)planting the big (columnar) cacti and euphorbias.

It’s simple: Plant it in such a manor that it can resist a strong wind without ‘bending over’ ending on the ground. And that you prevent the plant from neck-rot.

Make a hole deep and wide enough; better a bit too deep and too wide. Make a soil mix as described in the contribution about cuttings.

Loosen the soil on the bottom of the hole and mix it with the self-prepared soil.

Top this with a layer of approx. 5 cm self-prepared soil.

Place carefully the plant in the hole and spread the roots. Top the roots with a layer of 10-15 cm of self-prepared soil.

Put large rocks in the hole around the plant with a distance of 5 to 10 cm from the stem. And that their tips stick a little bit above ground-level.

Put the rest of the self-prepared soil in such a way that you compact the soil between plant and rocks. And that you shape a small heep around the stem ending at the outer-side of the rocks. This will let the surplus of rain water drain away from the plant keeping the neck as dry as possible.

This method has the ‘disadvantage’ that you have to plant deeper as they were at the nursery or in the pots. This extra depth means a year (or more) of growth before the plant, above ground-level, is as high again as you bought it.

The big advantage of this general method is, provided you did it right, that the columnar cactus or euphorbia will stand as a rock in the wind.

We learned this method in a natural way in one of our gardens. When this first cactus garden in South Africa was planted almost a 100 years ago Marthinus Malherbe planted all the collumnar cacti and euphorbias that way. During the restoration of this garden we had to take (after 24 years of neglect) almost all succulents out and remove the contaminated soil. Removing the big ones was quite a job for their root-system was covered with huge rocks. But not one columnar cactus or euphorbia  ’tipped’ in 90 years despite the heavy winds every now and than.

Rot

Whatever you do to avoid it; sooner or later there is a plant with rot. We recently experienced this with a quiver tree which prosphered in one of the gardens for more than 6 years. And suddenly, at the brink of the South African Autumn, the tree let us know that there was such a ‘soft feeling’ at its neck. Taking the soil away we discovered that part of the neck just started to rot. We took it out (almost 150 kilogram) and laid it to rest in the barn. The past week we’ve taken the rot parts away and let dry for the next few months until Spring before we replant it. Luckely for both, us and the tree, some of the roots were not attached. In October we will replant the almost 3 metre high tree on a somewhat higher spot and we’ll cover the neck and the top part of the roots with coarse sand for better drainage.

Rot can never be avoided in full but some measurements can avoid at least 90 percent of the misery.

It starts with buying your succulents.

And plant them in the right soil; more or less the mix as described in one of the contributions last month.

The top layer of the soil should be 30 to 50 cm deep and the subsoil should  be able to drain the surplus of water sufficiently even after a heavy rainfall.

Keep the soil around the plants free of weeds.

Plant vunerable succulents on a small sandy heep (5-10 cm high).

After (heavy) rainfall aerate the soil around the plant (loosening the top few centimetres).

But still than, as in our case with a very valuable quiver tree, rot can strike suddenly.

Neck-rot is caused by phytophthora. This is a fungus which also occurs in potatoes and caused the Irish famines in the 19th century and with that the Irish influx in the America’s.

There is not much what you can do in a natural way other than taking the affected plant out and cut the rot part out. If you discover the disease in a late stage it can be too late for the whole plant. The only thing left is to cut the plant off above the neck and let the stem dry first and than root again as a cutting.

ALWAYS remove the soil around the affected plant (it might be contaminated) and do not add the attached parts (or whole plants) to the compost heep for it will spread the disease to all the places where you spread the compost.

Connie Krochmal, the cactus and succulent editor of Bella Online, recently wrote an informative article about all kinds of (rot-related) diseases in cacti and other succulents such as fusarium, botrytus and (powdery) mildew.  

At last but not at least: communicate with your plants. They will tell you about their needs, their shortcomings, their symptoms of ‘illness’. Talk with them with your eyes, your fingers, you nose and also with your mouth. It helps. Really.

About Crassulaceae

The Crassulaceae or orpine family consists of 33 genera with a total of around 1400 species. These dicotyledons have the characteristic that they store water in their leaves. Most species are native to Southern Africa and the Northern Hemnisphere.

Another characteristic of this family is that the different species hybridise easily. Advised propagation is (leaf-)cuttings but for gardeners who like to experiment with cross pollination the crassulaceae are very rewarding.

All crassulaceae originate from areas where water is (sometimes) scarce.

In the Western Cape: no additional water in Winter but during long dry spells in Summer Crassulaceae will reward you with extra growth if you give them a good morning soak once every week.

Tip: cut flowerheads out of young plants. This will stimulate growth and spread.

Soil: In general Crassulaceae are not fuzzy about soil as long as it drains and the pH is somewhere between 6.5 and 8. They even grow in heavy clay but too much clay has the disadvantage that after heavy rainfall followed by high temperatures there is a risk of rot.

Pest and diseases: Most common are aphids which are a real pest for some Crassulaceae. Aphids can become a plaque during high temperatures after rainfall.

Crassulaceae originate from areas with a wide scope of temperature-zones (USDA 6-10/11) but most from (sub-)tropical climates.

In South Africa we experience regulary that overseas Crassulaceae like the ones blonging to the genera of Aeonium and Echeveria are sold as “indigenous” by nurseries. Maybe because some of the species of these genera are common in many South African gardens.

Some of the more common known, except the ones mentioned, genera of the Crassulaceae are:

Dudleya; Sempervivum; Sedum; Tylecodon; Cotyledon; Andromischus; Monanthes and Kalanchoe.

Three of our favorite Crassulaceae:

Kalanchoe marmorata: Originate from Ethiopia, Sudan, Kenia. This Kalanchoe has paddle-shaped blue-green leaves with purple markings. Attractive in any rockery of succulent garden. Large white pinwheel flowers in clumps. Easily to propagate with (leaf-)cuttings.

Crassula columnaris (“koesnaatjie“): This monocarpic dwarf (Western and Northern Cape) needs at least 5 years to mature and becomes 5 cm high. When mature it starts to flower. It can grow in full sun in well drained (slightly alkaline) soil. The plant will tell you when it needs water (shriveling leaves). The scent of the flower is divine. Propagation by seed or leaf-cuttings.

Kalanchoe orgyalis: This native from Madagascar is relatively rare in cultivation. This Kalanchoe has thick velvet-like leaves which makes it sensitive in climates with a high humidity. The leaves are silver toned mahogany coloured. The flowers are bright yellow. This specie becomes about 50 cm high but that can take a while. Kalanchoe orgyalis is very, very slow growing in comparison with the other species of this genus.

About Aloes

The genus name Aloe is derived from the Arabic, alloch and translated as allal in Greek and Hebrew, literally meaning bitter or bitter sap which is descriptive of Aloe sap. The genus Aloe belong to the family Asphodelaceae to which also other succulent genera such as Haworthia and Gasteria. A widely spread misunderstanding is that also the Agave and related American genera belong to the same famly. These belong to the family of the Agavaceae. Some Aloe species (f.e. A. Ferox, A. Barbados and A. Socotrine) are valued for their medical properties. There is however a large number of medical claims which are not scientifically proven up to date or are proven to be false. The globally best known Aloe is the Aloe barbadensis (better known under the previous botanical name Aloe vera). The Aloe barbadensis is commercially cultivated in the USA, Australia and India. In Maharashtra, Madhya Pradesh, and Gujarat, India, Aloe vera is raised as an organic. The crop is ready for harvest after 18 months from sowing. The average yield for organically grown aloe is approximately 12 t/ha. 

 Soil

A slightly alkaline (up to pH 8.5) sandy loam soil is the  most ideal for most Aloes but some prefer slight acidic soil (pH 5.5-6.5) such as A. mitriformis (A. perfoliata) and A. plicatilis. It is normally propagated through root suckers or by cuttings of the new growth. Because Aloe plants consist of 95% water, they are extremely frost tender. If they are grown outdoors in warm climates, they should be planted in full sun, or light shade. The soil should be moderately fertile, and fast draining. Established plants will survive a drought quite well, but for the benefit of the plant, water should be provided. 

Pests:

All known garden pests can be kept to a minimum by simply ensuring optimal growing conditions and a good selection of plants that attract wildlife to your garden. In principle a garden is always un-natural. One of the challenges of organic gardening is to make use of nature in order to strive towards an ecological balance. For our and your dissapointment: even nature is never in balance. There are many ‘surprises’ every year but without ‘ecological measurements’ these can go a bit out of control. A daily ‘inspection’ walk in the garden -preferable early morning or late afternoon- helps the gardener to foresee ‘threatening’ pests and diseases and making the right decisions towards preventive measurements.

Most common pests/diseases in aloes are aphids, scale insects and cancer.  

For scale insects the best results are obtained by physically removing scale using a cloth.

Occasional aphids on flower clusters and scale insects on leaves. These are relatively easy to control with water (high pressure) of, even better, preventive with a tea of garlic. Aphids are ‘farmed’ by ants. The ants regard aphids as their ‘milk cows’. Keeping ants away, two rings (10 cm or 4 inches space between them) of chalk powder on soil around aloes, minimalise the number of ants and aphids. 

Cancer: Caused by aloe-cancer mite.  This mite lives inside the plant and is the carrier of the virus and cause the cells to multiply and form ugly weird growths.  Cut out the affected part of the plant and let it dry.  General info about pest control and pest and disease prevention can be read elsewhere in this blog  

Propagating

Propagating is best done via cuttings. Sowing is also possible but bear in mind that Aloes hybridize easily. 

Southern Africa is home to a few hundred Aloe species. Two of our favorites are the Aloe perfoliata and the Aloe polyphylla. 

Aloe perfoliata

Growing A. perfoliata is very easy. The best results are achieved by simply making stem cuttings. Allow cuttings to dry for a few days and insert into river sand and keep moist. The roots appear after about two weeks. Seeds must be sown as fresh as possible. When kept too long they are parasitized by small crawling insects. The best time for sowing would be in the winter, June to July. Use coarse river sand and cover seeds lightly, then keep moist. It is advisable to treat seeds with a tea of khaki-bush, as seedlings are prone to damping off, a fungus that eventually kills the young plants. Simply add tea to the soil. After germination, when plants are about 20 to 30 mm, plant over using a sandy-loam medium. If you have a garden with clay soil, use some bone meal to break up and nourish the soil. Mature plants in the garden may from time to time be subjected to attack from scale insects and aphids.

Aloe polyphylla originates from high, relatively cold, altitudes in Lesotho. It is a very difficult plant to cultivate in the open in the Western Cape. It’s main requirement is well-drained soil. It performs best when planted on a slope (or planted up at a slight angle so water does not collect in the spiral), where it can enjoy sun, or part (afternoon-) shade in the hottest areas. It also does well in pots. Water requirements depend on soil and weather. They are generally suited to low water, but prosper with some summer water. 

Information about South African Aloe species can be obtained via one of the websites of the National Biodiversity Institute. This site contains a wealth of info of many indigenous plants including succulents.

Plant identification

If you want to experience pathetic behaviour amongst botanists (not all): invite them to identify plants. You will think you’re in a Kindergarten fully out of control.

Partly this has to to with ongoing hefty debates about names (in fact it’s all ego-politics) and partly it has become very difficult to identify because of hybridisation of plants. Officially, to provide you with an example, there are globally 8 species of the Plumeria (‘frangipani’) but only recently we discovered that the ones sold in south Africa are merely hybrids …..

The best contemporary way to identify plants is via DNA-research. Very expensive though.

A few sources for plant identification are SANBI, USDA, and the Univerity of Pretoria; the latter one also offers courses in this subject.

At Soekershof Walkabout we still have plants of which we know the genus but are not sure about the specie name. And we are not ashamed of that.

We also learned to be very suspicious at nurseries (even the ones of botanical gardens) where the full botanical names are labelled.

Pest and disease control; the ‘green’ way

Despite all precautions the green gardener undertakes there is always a moment that some pests and diseases become uncontrollable in the succulent garden.

These are in general all related to the unpredictable weather such as flood rains; fluctuating (significant) temperature changes, etc.

Also we have to battle with these, unforeseen, ‘surprises’.

Prevention is always the best and despite good drainage, good weed control , hygiene and other measurements there are those tempting moments when aphid-populations on plants are becoming ‘over-crowded’ and fungi-, bacterial- related diseases threaten to destroy your plants.

There are a few good green alternatives to keep pests and other diseases under control. In our garden we apply them with success.

The first smelly one is the use of khaki bush (Tagetes minuta); a South African native but also in cultivation in other parts of the world. Twice a year applied to the soil just before rainfall it will keep the fungi- and bacterial related diseases (f.e. neck rot) at least under control or even diminish the rest totally. Fill a bucket with this ‘weed’ and poor boiling water over it. Let it rest for a few days and than apply it to the soil in relatively large quantities (better plenty than less plenty). Apply it in late Autumn and the beginning of Spring.

Insects like aphids and scale insects can be kept under control with a garlic (Allium sativum) tea. Crush the garlic. With crushing a natural sulphur compound is released and this compound does the job. 100Grams crushed garlic for every 10 litres of boiling water. Add a spoon of pure butter (this will make the mix nicely and equally flow out over the plant). Mix it thoroughly and let it cool of. Than filter it and mist-spray over the plants. It will keep insects away and a surplus of insects on the plant will try to find another source. One disadvantage: you will have to apply this mix every 3 or 4 days (during ‘high insect traffic periods’) but it is effective; most effective when you can foresee an expansion of the insect population. For example high temperatures after Summer rainfall.

Also effective and sometimes ‘advertised’ as green is a mix of white spirit and soap. Even if the soap is fully bio-degradable it’s not our favorite because the white spirit can be harmful for some sensitive plants (damage of chlorophyll).

Landscaping a rockery

Creating a garden is not always as easy as it looks like; expecially when you intend to create a special garden.

A rockery is a speciality garden and to make it right you’ll have to go through a lot of trial and error but the end result (end result? a rockery is a never ending story) makes it worthwhile.

To avoid starting up problems/errors a few general guidelines:

1) Soil must have good drainage.

2) Create slopes which, in cases of flood rain, let the overload of water drain away.

3) Arrange rocks in such a way that sensitive plants are protected against wind, rain and sun

4) When choosing plants you must have a good idea of what you want; large plants, small plants, colours. Advise: do not buy and plant all at once. Better is to start with a few focal points and  - as in the ongoing process ideas can change – buy and add with intervals the ‘filling up’.

5) Choose plants which are suitable for the local environment. Some plants can also kept in pots which you can cover up with rocks. Handy in case you move to another location and also a necessity for some plants in certain local environments. Maybe it’s even advisable to keep all the plants in pots so you can shuffle them around for a month or so in order to get a better idea of the look of your rockery from diverse angles. The disadvantage of plants in pots is that you will have to re-pot them every 2 to 3 years and that they won’t grow that fast as in the open.

6) Composition of the garden is essential. Always try to find a balance between shapes, colours and flowering seasons. A rockery should be attractive the whole year.

7) The art of making a rockery is that you are able to create a personal one with an own sphere. To achieve this you should visit and look into as many rockeries as possible and talk with the makers. This is a big help for you can learn of the trials and errors of others and you get a better insight in your own idea with all possibilities and especially the impossibilities. It surely will avoid a lot of misery although you will never be able to avoid all. And sometimes it’s good to go against every logical thinking. In this orientating process your original idea will mature into a unique rockery, whatever the size of it.

See also Landscaping a rockery PART 2

About succulent cuttings. It’s all in the fingers!!!

Propagation by seed is the most rewarding method because you see the seed germinating and the plants growing. But except for the extra amount of work this method is also time consuming. Cuttings have the advantage that they already have a certain, more mature, size thus faster fully growing plants.

Herewith some general guidelines:

 Cuttings can, in general, best be taken at the end of the dormant season. Those of cacti and cacti like euphorbias between October and the end of February (we’re in South Africa, remember). Let the cuttings dry for at least some days and plant them in a soil mix of 90% coarse sand (eventually mixed with some fine grit) and 10% sift compost. Moisterise (not wetten) this mix with kelpak (SeaGro) (50cl kelpak in 10 l water) and let this mixture dry for a few days. Kelpak, by the way, is a seaweed product from Simonstown which stimulates the root-growth. Plant the cuttings up to one-third of their length in this mixture (in pots; deep seed-trays) and do not water for the first week or so. Put the pots/seed-trays with the cuttings in a large tray with water and let it moisturise from down under for 10 minutes. Not more. Mist-spray the cuttings every morning and evening lightly and as soon as the soil tends to dry out next soak-from-down-under for 10 minutes.

This method is most suitable for (almost all) cacti and cacti-like euphorbias and is also applicable for most other succulents. In a later stage, when we describe the different groups of succulents, we come back on this subject.

One remark: when taking cuttings from cacti-like euphorbias and other succulents (including caudiciforms) with poisonous sap special precautions have to be taken. Keep the cutting under a running tap until the all sap is secreted from the wound. Always wash hand afterwards. And never take those cuttings in the heat of the day; always as early as possible in the morning. Wear protective clothing.

Cuttings of succulents, other than cacti and cacti-like eurphorbias, (such as crassula sp., mesembs, etc): directly after cutting in soil-mix as described above and mist-spraying at least 3 times during the day. Soil has to be damp (NOT wet).

The cuttings of some cacti species take their time to make roots, sometimes even up to one year of more. Others are rooting within a few weeks. Always be patient and watch your plant-material. It’s a way of communicating. The plants will tell you a lot. It’s a kind of ‘body-language’.

Once we had a student (Technikon-horticulture) here for his practical. From the books he knew exactly how to propagate. We gave him the chance to do it his way and one of our staff did it his own way. The result: Student less than 1 out of 10 cuttings/seeds growing; staff member more than 9 out of 10. Lesson ‘numero uno’ with propagating: it’s not all in the heads or books but in the fingers. If the fingers are not ‘green’; theory will not work.

It’s like how a great ’chef’ distinguise him/herself from ‘cooks with books’.

About buying cacti and other succulents

The majority of people buying cacti and other succulents don’t really care if their purchased plants die after some time; they just buy a replacement. These are fortunately not our customers (and that is very un-commercial!!!).

The real passionate gardener, hobbyist, etc. buys with the intention to enjoy his/her plants for a long time. These are the people we like to welcome in our nursery and they are invited to be critical and during many of such occasions we experience an educational interaction to the benefit of all.

First something about our own experience. In the beginning (we didn’t know that much about the subject and we are still learning) we bought quite a few Aloes at one of the botanical gardens in the Western Cape. The plants were nicely labeled with with their full botanical names. Almost all turned out to be hybrids. At a specialist succulent nursery we bought 12 cacti of which 8 had a ‘hidden’ (underground) disease.

Botanists are in continuous discussion with each other about botanical names and during identification of certain group (genus) of plants. The Aloes are very good example because these hybridise easily and proper identification, in case of doubt, can only be done with DNA-research. THE Haworthia ‘specialist’ of South Africa is very honest when he says that he is unable to generate a proper identification key which covers all Haworthias and that he has difficulties to identify some of the Haworthia-species. With other words: don’t always be too sure about about the botanical names with which plants are labeled. Another issue is that many botanical names are changing nowadays because of DNA-research (f.e. part of the Stenocereus species becomes suddenly Cleistocactus or whatever) and that makes it even more complicated. A self-respecting nursery man will, in case of doubt, always label ‘spp’ after the genus name; f.e. ‘Mammillaria spp.’

How can one check if the plants are healty? This is not always easy but you can take some precautions. Is the nursery clean, relativily weed free and do the plants, on first sight, look healthy? This is the first impression. If the first impression is not good be extra critical.

Some hidden diseases are difficult to identify such as roots which start to rot at their tips. Even if the plants look healthy but you see that they are waterlogged (and not just after a heavy rainfall) be critical. Some nurseries use quite a few fertilisers,pesticides, fungicides and so on to let the plants look healthy but once purchased you will have to apply these chemicals until you are pretty sure that they are adapting to your preferred way of gardening. Once we were at a succulent nursery where the plants were covered with a blue layer caused by the application of copper sulphate.

Golden tip, which prevents you in at least 70 percent of such cases of ‘buying a cat in a bag’, is removing the soil around the neck of the plant. If the tissue is not soft(ening) but feels solid the plant might be healthy. This applies surely for all Aloes, Caudiciforms (especially adenium- adenia- and cyphostemma sp., Lithops, Cacti and cacti-like Euphorbias.

Almost at last but certainly not at least: Most nurseries sell their plants from under a roof or shade net. Advise (especially in Summer): Don’t put the plant right away under the sun, once at home. Let the plant slowly get adepted to the sun. This can be done by providing the plants with morning sun and afternoon shade for the first few days and let them gradually stay longer in the sun until, after a week or so, they are used to the sun. Some plants, amongst others Echinocactus crussonii (Golden Barrel Cactus or Mother’s in Law Seat) need sun protection for the first year until they are established. Keep the plant covered with a shade net (at least between 12 and 4 PM) from the second half of December to the second half of March. A good nursery with in-house knowledge will give you decent information. If the

Damage on a plant caused by snails and (scale-)insects are in general not terminal and can even give the plant a natural charm. In nature you won’t find that many plants (=relatively) which are looking perfect. On the contrary but these plants are strong with some build in resistance.

About literature

There is, to our surprise, quite a few books about cacti and succulents; including ones with beautiful pictures.

In South Africa some of the books are available in the shops of the botanical gardens of the National Botanical Institute, others are available at bookshops (or they can order them for you) and there is also the possibility of mail-order. Silverhill Seeds and Umdaus Press both have a list of succulent related literature which I left out of the list below.

Books of interest (both for beginner and advanced succulent gardeners) are:

‘Cacti, the compact study guide and identifier’ by Charles Glass and others. ISBN 0-7858-373-4

‘Gardening with succulents’ by Prof. Gideon Smith. ISBN 1 77007 082 6

‘Vetplante van Suid Afrika’ by Ernst van Jaarsveld and others. ISBN 0 624 03901 3

‘Succulents, the new illustrated dictionary’ by Maurizio Sajeva & Mariangela Costanzo. ISBN 0-88192-449-0

‘The illustrated encyclopedia of cacti’ by Clive Innes & Charles Glass. ISBN 0-7858-1358-6

‘Cacti & Succulents’ by Hans Hecht. ISBN 0-8069-0548-4

‘The complete book of cacti & succulents’ by Terry Hewitt. ISBN 0-7894-1657-3 (this was our first book on the subject)

‘Guide to the aloes of South Africa’ by B. van Wyk & G. Smith. ISBN 1 875093 41 9

‘Mesembs of the world’ by Gideon F. Smith & others. ISBN 1 875093 13 3

‘The cactus family’ by Edward F. Anderson. ISBN 0-88192-498-9

This is just a selection but it gives you something to read for the first few years.