Bay area Tulipa

Nathan Lange
Thu, 11 Apr 2013 15:55:04 PDT


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...


At 02:27 PM 4/11/2013, you wrote:
>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 Licht, Director
>University of California Botanical Garden
>200 Centennial Drive
>Berkeley, CA 94720

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