I don't know about blue porch ceilings, but do recall a plant
bio-physiologist friend at university doing experiments which indicated that
a particular shade of blue caused an inhibiting effect on the growth rate of
certain plant structural cells.   The result was to cause an upward growing
plant to appear to turn toward the blue.   In fact what was happening was
that the inhibiting factor on the blue side of the plant was allowing the
other side to grow faster, causing the stem to bend.

This was in 1970 when heat conservastion was becoming a fad and techniques
such as earth sheltering and reduced northern exposure were being tried in
greenhouse designs to save heat loss.   Plants in the new greenhouses with
glass only to the south appeared to turn to "seek out the light", so to
speak, leaning over and causing all sorts of problems for tending and
harvesting.   The practical application of my friend's work was to paint the
non-glass portions of the greenhouse ceilings the shade of blue most
responsible for the negative growth phenomenen ( of course it was "sky
blue") and the plants then grew nice and straight like all little productive
plant soldiers on the assembly line are supposed to.

So, when you look at a nice straight plant stem, you can think of the equal
inhibiting effect from sky blue on all sides above which is causing it.
Maybe granny painted her porch ceiling blue so the geraniums wouldn't list.

I wonder what effect blue eyes have on leaning ?

Respectfully,
Cuyler Page
Kamloops, British Columbia

PS :  Come visit the Kamloops Museum if you are passing through on the
Trans-Canada Highway.   I know a nice Swiss bakery for lunch that also makes
a great latte.

PPS :
If you are anywhere near the central Washington State border with Canada,
drop in to the Grist Mill at Keremeos, BC on weekends and I will treat you
to lunch in our organic garden tea room.   Our 1877 historic site is so
clear sky healthy organic that all our plants grow straight up !

>What is behind painting one's porch ceiling blue?? I had read before that it
>inhibits some sort of insect from nesting on said ceiling, but the whole
>thing is a blur. I bet someone out there has the answer...
>Cheers, Molly
>
>Hayles & Howe Ornamental Plasterers
>3500 Parkdale Avenue
>Building One West, Ground Floor
>Baltimore, Maryland  21211
>410.462.0986  (F) 410.462.0989
>http://www.hayles-and-howe.com/
>