Dear All, Initial, but intensive, reading of the Deno document (referred here by David Pilling) has produced some interesting information for me. Others such as Jane McGary commented on shortcomings with Deno's work. Those points may be valid for rock-garden seeds but my orginally query was about seed germination from sources not my own. So, I searched from information relevant to that topic, with emphasis on the south African, bulbous iridaceae species. I found several. Here is one gem: "Romulea (Iridaceae). Both R. bulbocdium and A. Iuthicii germ. at 40 but not 70. J. Forrest reported that R. hantamensis germ. 96% in winter using his own fresh seed whereas fourteen samples of imported DS seed failed to give a single germination." So, it seems that Romulea seed imported from elsewhere did not germinate well. It would be interesting to know the conditions under which the fourteen seed samples were imported but, on the surface, Forrest's results would appear to confirm mine. Deno describes the effect of oscillating temperatures, a well-known initiator of germination in winter-growers, but does not indicate whether it was used in many of his species tested. There are other observations on this topic I could add that may surprise some and possibly irritate others but let's just leave it at that for now. I am still in the research mode and have more to learn. Andrew San Diego