[pbs] What promotes blooming?
Jane McGary
janemcgary at earthlink.net
Sun Oct 14 13:09:08 EDT 2007
I haven't been following this thread too closely because I know that I will
never get Nerine or Crinum to flower here, but I should mention, in
addition to absolute temperature in terms of daytime highs, many plants
seem to be sensitive to temperature FLUCTUATION. In areas where atmospheric
humidity is low in summer, such as the American West (especially outside
large cities, which experience a "heat island" effect), the difference
between daytime and nighttime temperatures is usually much greater than in
areas with high atmospheric humidity, such as North America east of the
Rocky Mountains. As a result, plants evolved in humid environments
experience almost nightly lows to which they aren't adapted, and so we in
the West often notice that plants from the East dwindle away over a few
years, however much we irrigate them in summer. I find the same to be true
of many plants from Japan. In respect to bulbs, this fluctuation would be
moderated within the bulb itself, but if the leaves of a summer-growing
bulbous plant (which are making food for the bulb and flowers) suffer a
"dormancy trigger" every night when the temperature drops 30 or 40 degrees
Fahrenheit (as it does where I live), this may affect bud formation.
I have no trouble flowering bulbs whose leaves are dormant in summer, even
those from warmer climatic regions near the shores of the Mediterranean.
Jane McGary
Northwestern Oregon, USA
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