Most bulbous plants can easily be propagated by seeds or by offsets. How to sow is described in many books, but there remain a couple of situations in which special skills or knowledge are needed. Bulbous plants can also be propagated by 'artificial' methods, which is especially interesting for those plants which don't produce seeds or offsets in cultivation.
I am especially interested in winter growing bulbs. These plants grow mainly in South Africa and I buy most of my seeds from Southafrican companies. In general they offer in their summer, our winter, seeds of winter-growers and in their winter, our summer, seeds of summer-growers. This leads directly to the first and most important problem. When you buy the seeds and sow them directly, you sow them in an unfavourable period. If you wait almost half a year to sow them in the beginning of the growing period, the seeds might lose germinative power. What to do?
In the past years I have developed a methode for sowing seeds from South Africa; the so called 'counter season sowing'. Which means sowing plants during the opposite season. I sow the seeds directly after I have received them. For winter-growers this is February and for the summer-growers August-September. The seeds germinate in the second half of their growing period or even during the dormant period. I water the plants during the 'dormant period' in order to let them grow. The young plants go dormant during the second half of the next growing period. This means the have had a growing period of almost one year. This method has been succesful with Bulbinella, Polyxena, Albuca and Cyanella. Less succesful were the experencies with Massonia, Lachenalia and Gladiolus.
Artificial propagation methods are methods like partitioning, scaling and leaf cuttings. With partitioning the bulb is cut from nose to bottom in several parts with a part of the basal plate attachted to every section. Scalling is a method where individuel scales are taken of the bulb or part of rings are cut of the bulb. With boths methods the parts are planted partly in the soil and adventitious bulbs will grow.
The most opportune moment to propagate bulbs like this is at the start of the dormant period. Adventitious bulbs will grow during this period and can produce leaves next growing season. I have done experiments with various genera and species, e.g. Albuca (upper picture), Galtonia candicans, Haemanthus albiflos, H. coccineus, Lachenalia mathewsii (bottom picture), Crinum powellii and Bowiea volubilis.
Leaf cuttings is a propagation method which can also be used for specialty bulbs. In the literature results with this method are described for a.o. Lachenalia and Haemanthus. I have done only experiments with Haemanthus albiflos. It takes a very long time before adventitious bulbs are formed and start to grow. Once they have a certain minimal seize the grow prosperously. If you compare it with growing plants from seeds, the bulbs from leaf cuttings grow much faster.