"Martin" wrote in message
...
On Sun, 19 Sep 2004 16:31:13 +0000 (UTC), "Franz Heymann"
wrote:


"Martin" wrote in message
.. .

[snip]

perhaps this http://www.hydroponics.com/light/growlamps.htm

I had a look

I think they are trying to pull the wool over my eyes, unless there
is
something fundamental which I misunderstand. I thought the light
was
only used by the plant for photosynthesis of carbohydrates from CO2
and water. So why do they waffle about spectra which are adjusted
for
good fruiting versus good vegetative growth?

dunno I am not an expert on the subject.

Maybe Jenny knows more?

From observation of light emitted from green houses, most of the
lamps
used *appear* to be sodium vapour lamps i.e the sky is a sodium
colour
at night in these parts. It's particularly noticeable if you
approach
Schiphol by air from the south.

That's weird, because sodium lamps give little more than the yellow
Sodium doublet line, and photosynthesis requires both red and blue
light. {:-((

I have little faith in an organisation which thinks the plural of
"wattage" is "wattage's"

Don't confuse scientific knowledge with basic literacy. :-)


Some of their internal links don't work.

I'll do a bit more googling and try to find out what the average
marijuana growing Dutchman in the street uses; or I'll check the
rubbish skips after the next police raid.

Do you mean "growing Dutchman in the street" or "Dutchman growing in
the street"?

Franz