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’.