Hi Arnold and others, Being a busy person I go for simplicity and have 2 basic mixes. 1 part commercial potting mix to 1 part coarse sand which is what I use for germinating most South African amaryllids including Clivia. My other mix is 2 : 1 of the above which I use for summer growing bulbs and generally less fussy genera , because it is slower to dry out . If I fertilize it is long after germination and usually with something soluble on a very irregular timetable. I add dolomite for some genera such as juno iris and arum. Cheers, Rob in Tasmania