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short day/long day

In a message dated 8/18/98 4:31:03 AM Pacific Daylight Time,
DebbynChris@earthlink.net writes:

<< Excuse my lack of knowing, but I`m a amature gardener,and a  darn`ed
determined
 one.
 
 what is a short day/ or long day onion?
 
  >>

Hi,  I'm going from memory here......

The terms 'short day' and 'long day' when used in conjunction with plants is
in reference to a phenomenon known as photoperiodism.  In other words,  plants
react in certain ways to the relative length of the days and nights, and
whether they are getting longer or shorter.  This is a mechanism that the
plants use to aid them in doing the 'right things' at the right time of year.
Photoperiodic responses coupled with other environmental factors such as
temperature are responsible for plants growing and flowers blooming in the
right seasons, and for subsequent fruit and seed set to occur at optimal times
for most efficient survival of the particular species.  

As the days get longer in spring and summer,  long day plants react to an
internal chemical(s) produced in response to this,  and they bloom.  Short day
plants tend to bloom as days are shorter.  And day neutral plants can bloom at
anytime the weather is conducive for growth.  Many weeds are day neutral.  

Photoperiodic responses can be manipulated in greenhouses where all
environmental factors can be controlled.  That is why short day plants such as
chyrsanthemums appear blooming in stores year round,  and why there are so
many pointsettias produced at Christmas time.

With respect to onions,  and this is my assumption since I am new to growing
onions from seed,  short day onions would do best planted in the fall as the
days are getting shorter.  And long day would do best planted when the days
are getting longer.  Most seed catalogs note whether the onions are long or
short day.  Candy is the only one I have seen touted as day neutral.

I hope this made sense.  Janet.
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