Paul, True, but this is the only historical chilling data that I know about covering multiple locations across California. If you know about a species flowering successfully in one location of the state, this data could help you predict your chances for success. Despite all the obvious differences between soil and air temperature, over time, soil temperature is indicative of air temperature and this could be more true during winter than any other time of the year. I offer that my anecdotal experiences with seed germination of species requiring stratification support this assertion every year. I did not suggest that these data addressed chilling requirements of different species, only that the wide variance in annual chilling of the warmer parts of the Bay Area during winter, like Berkeley, could result in significant year to year differences in flowering of any given single species whose chilling requirement is close to the coldest expected winter. When growing such a species, successful flowering one year could easily be followed the next by disappointment and visa versa. Knowing that could help determine planting location since, as you pointed out, soil temperature can vary significantly from air temperature. Also, if you are only interested in species whose flowering will be successful every year, this data gives a starting point of how much minimal chilling you can count on every year relative to other areas of the state (where perhaps you saw the plant of interest flowering well every year). Since these are "University of California" data that we are discussing, perhaps someone in your esteemed position would have considerably more influence than most in attempting to persuade the necessary UC entity to record ground temperatures along with air temperatures. I suspect this is when you bring up funding... Nathan At 02:27 PM 4/11/2013, you wrote: >Nathan >Your comment on the importance of microclimate variation is >obviously relevant. However, the chilling data you refer >seems to lack too important elements for us: they refer to >air, not ground temperature and they do not address how much >chilling each bulb species requires. >Paul > >Paul Licht, Director >University of California Botanical Garden >200 Centennial Drive >Berkeley, CA 94720 >(510)-643-8999 >http://botanicalgarden.berkeley.edu/