Bay area Tulipa
Nathan Lange (Thu, 11 Apr 2013 15:55:04 PDT)

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: