Roridula is quite tricky in cultivation. Most people will obtain seed and here the problems beginn to start. Both species are germianting in nature after bushfires have cleared the vegetation. So heat or chemicals (or only more light reaching the seeds?) is necessary for germination. The positive sideeffect is, that the seed of Roridula can be stored for many years.
Roridula gorgonias is relativly easy to germinate and sometimes seed is germinating whereever it had fallen. The best way is to sow it on the surface of a mixture of equal parts peat and sand. Place the pot in a very sunny place with hot daytime temperatures and cool nights (September or March are good months to try in Germany). It is beneficial for germination if you burn some dry grasses on the top of the pot after a few days, but usually it is not necessary. Germination can occure after two weeks, but some seeds can take up to three months.
Roridula denatata has the reputation of beeing very difficult to germinate. I obtained some seed from Silverhill seeds (South Africa) and made some experiments. The result is, that it is not necessary to use gibberlin acid. Seed didn't germinate if placed in a hot and dark room. Seed also didn't germinate when placed in my highland terrarium with warm days and relativly cool nights and medium bright light. But seed germianted (with and without a treatment with gibberelin acid) at a rate of about 60% when placed at a very sunny place at my greenhouse with hot days and cold nights. I treated all of the seeds by burning some dried grasses on the surface of the substrat. Propably it is not the heat and not the chemicals which stimulates germination in natural habitat, but a lots of light reaching the seed after the fire had burned away all other plants.
In spring 2002 I again sowed 6 seeds of Roridula dentata, put them at a sunny place, kept them wet and in August/September (hot days and colder nights) three of them germinated. I didn't use any treatment except burning some grasses on the pot's surface.
In my experience germination of Roridula dentata can take many months so don't throw away your pot to fast.
I have heared about other successfull experiments using liquid smoke, gibberelin acid or freezing the seed but I can get a germination rate of 50% with my method and it is very simple.
Copyright © 2001, 2002 by Martin Reiner - last update 2002/10/04