Lou Jost and Diane Whitehead added some interesting climate variables to consider. Both mentioned fog, which in coastal and some alpine regions provides moisture where there is no rain. There are several "fog deserts" in the world, the most notable being in Namibia and northern Chile. I don't know if there are any bulbs in Namibia, but there are many in northern Chile; however, when it doesn't rain (i.e., when El Nino does not occur), many of the bulbs do not appear above ground that year. The fog keeps the sclerophyll shrubs going, and some of them flower even without rainfall, but it doesn't moisten the soil enough for the bulbs to grow. Diane mentioned "the intensity of winter light in Arizona," and this reminds me that I always notice the difference in habit between bulbs I've grown in my frames and the same species grown in alpine houses in the UK. The latter tend to be taller and "drawn," and I suppose this is due to the difference in winter sunlight, since I'm at a lower latitude even though it's colder here and often cloudy. The depth and persistence of winter snow cover, also mentioned by Diane, is very important for the survival of alpine species. If you have reliable winter snow cover, you should experiment with alpine species from many parts of the world, even if you perceive the climate there as much warmer than yours. I found this out (too late!) when I gardened in Fairbanks, Alaska. Jane McGary