This month in the garden

Every now and than we shoot in the garden; not with a shotgun but with a digital camera. Here 5 pics; one shows a part of the garden (totalling 11,000sqm and over 2500 different succulent plants outdoor); one showing an elephants foot (Dioscera elephantipes); one with a fruiting Pilosocereus lanuginosus; the fourth is a Adenium arabicum with flowers AND seedpods and the last is an overview of our retail nursery. It’s not all succulent here in The Green Cathedral of South Africa but that’s for you to find out; preferable on the spot where you can feel, touch, smell, hear and see.

Where to get viable seeds?

The most rewarding way of enjoying your plants is growing them from seeds. But we understand that not everybody has that much patience and growing plants from seeds is also very labour consuming.

But once the decision is made one wonders where to get the seeds. Ordinary nurseries generally only sell cactus seed mix but for people who want to grow something special it can be difficult to find the right adress for the desired seeds. And than there is always the risk that seeds do not germinate. We’ve had our experiences with that.

One of the few specialised succulent growers with good quality seeds can be found in The Netherlands (more than 80 percent of the seeds germinating; via friends of friends we got around 50 packets. In comparison average less than 10 percent of  germination rate of seeds acquired at South African seed suppliers including the National Botanical Society) . In the online cataloque (secure payment method) of CactusPlaza you will find seeds of over 5000 different succulent species including cacti, mesembs, caudiciforms, etc.

The Dutch supplier states that its seeds are not older than 2 yrs at the most and that most probably explains the high germination rate.

About Euphorbias

The Euphorbiaceae family consists of around 300 genera and about 7500 species of which approximately 870 are succulents. About 50 genera and 487 species are native to Southern Africa including Madagascar. These figures excludes the numerous varieties and hybrids such as those of the E. milii and E. pulcherrima (pointsettia).

The International Euphorbia Society covers the whole spectrum of this plant family including the non-succulent ones.

General information about succulent Euphorbias can be found here. The most valuable Internet source (including photo’s and cultivation info) however can be sourced at this site.

Euphorbias are named after the Greek surgeon Euphorbus.

Most of the succulent species of the Euphorbia are easy to grow in most parts of South Africa provided that there is sufficient drainage and the humidity is low. High humidity causes mildew and, combined with high temperatures, mealy bugs. Good drainage prevents Euphorbias from root mealy bugs and root rot (caused by fusarium fungus). Plant Euphorbias preferable on a slope and in well drained soil. Large collumnar plants always surrounded by rocks. In general Euphorbias are less susceptible to diseases than other succulent families. In the past we already submitted something about pest and disease control the green way . See also this contribution and these ones.

Propagation can be done by sowing and by means of cuttings.

Some Euphorbia species hybridise easy and to prevent this as much as possible is hand-pollination with a brush. Always plant two of more plants of the same specie next to each other.

As for cuttings: cuttings of succulent Euphorbias can best be taken towards the end of the dormant season. We normally take them towards the end of the South African Summer (February-March) and always in the early morning but preferable in the late afternoon. Keep the cuttings under a running tab until the cutting stops ‘bleeding’ latex. This milky sap is poisonous (always wash your hand afterwards and or wear protective clothing). Let the cuttings dry in a dry shady area with good ventilation for at least 3 to 4 days before planting them.

Boojum Tree

A little problem: For a few years now we try to acquire seeds of the Boojum Tree and without any succes. We wrote (e-mail) to virtually any succulent nursery in the USA and Mexico including the ones which advertise the seeds of this Fouquieria columnaris but not a single reply. The Boojum Tree, we’ve figured that out already, is one of the (growing) monumental plants we miss amongst the other species of the Fouquieria genus which are growing very well in our environment.

So; here is our enquiry: who can supply us with viable seeds of the Boojum Tree?

Send your comment of e-mail us: soekershof -at- lando.co.za

Thanks.

 Yvonne & Herman

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.

About sowing succulents

Sowing seeds from your own plants is the most rewarding way of propagating. You see the seeds germinating and young plants grow into mature ‘ornaments’ in your garden.

There are also a few disadvantages: it’s time consuming and labour extensive.

It all starts with the harvesting and cleaning of the seeds.

Bear in mind that some plants hybridise easily. You might think you have seeds of the Aloe ferox because your harvested the seeds from an A. ferox. But whatif this aloe was pollinated by an Aloe vera? We’ve learned our lesson with this. In the beginning we bought quite a few aloes at one of the National Botanical Gardens in South Africa; all nicely labeled with their botanical names. Almost all turned out to be hybrids. Some cacti and caudiciforms (i.e. cyphostemma sp., pachypodium sp.) also hybridise easily. To avoid this for at least 95 percent it’s the best to plant more succulents of the same specie in a group (not nearby species of the same genus) and pollinate manual with a brush. Manual pollination is also a good way of communicating with your ‘babies’.

The best results are achieved with fresh seeds. In general the viability of the seeds declines in time; sometimes even after a month or so. Take the seed-pods from the plant, wash the seed thoroughly (most of seeds are ‘packed’ in an ‘inhibitor’), let the cleaned seed dry and than sow. That sounds easy but it is not always like that. Special precautions have to be taken when harvesting and cleaning the seeds from amongst others euphorbia- and cyphostemma species. The sap of the cyphostemma berries can cause irritation and that of the euphorbias is poisonous. Wear protective hand-gloves when cleaning those seeds. In the description of the different succulent families and individual plants in the future we will indicate this precaution.

 There are several recipes for soil mixtures and sometimes they  differ per family, genus or even per specie. Each nursery has its own special recipes and all of these seem sufficient. Most books advise you to use a cactus mix which can be purchased at nurseries. Some succulent nurseries apply vermiculite or perlite mixed with a little bit compost. It works nicely and we have tried it a few times on a small scale with good results. But we do not like to apply unnatural products to our soil mixtures. Another disadvantage on the longer term is that if you keep your plants in the original nursery pots with these unnatural products without re-potting them in a proper mix; their lifespan will be shortened.

For most succulents we use for sowing a simple mix of coarse sand (eventually added with some fine grit) with approx. 5 percent fine compost. Mix this thorougly and add some kelpak (SeaGro) dissolved in water (50 cc kelpak in 10 litres water) until the mix is damp (not wet). Fill the seed-tray(s) with this mix, sow and top it of with a layer of sand with the thickness of the seed. In the heat of Summer we top it with a water retaining layer of sand/clay (1:1) mix or clayish loam. This general method works for at least 90 percent of the different succulents with a high (or at least above 70%) success rate. In the description of the different succulent families and individual plants in the future we’ll come back to this subject.

After sowing keep the soil damp. Depending on the temperature mist-spray regularly. Never let the soil dry out. An option is also to cover the seed-tray with transparent plastic foil. If you seed in pots you can use the top of a cola bottle to achieve the same effect.

As soon as the seeds are germinated take this cover away and give the pots/trays a 10 minutes soak from down under as described in the chapter about cuttings

And again: this is all a rough outline. As described before: it’s all in the fingers (not only in your head or in books). Every gardener develops his/her own way of doing things. This rough outline provides you with a nice start for one of the most rewarding things-to-do.