10-04-2004, 04:02 PM
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Confusion! Help Ray!
(TZ) writes:
Unfortunately, published footcandle measurements for orchids are for
natural daylight at noon in greenhouses. This means that morning
I do not agree.
My tables say minimum 40klux (about 3700 fc) to get a semiterete
vandaceous plant to flower, with the ideal between 55 and
70klux. Strap-leaved variants need lower light, but I can't seem to
get them to live through the winter. Oh, well.
I have now moved one of my ascocendas from a 30klux to a 45klux
position. It had just been sitting there for a year without spiking
while I figured out what it could take when it comes to watering.
Within two weeks, it had produced a spike. I have not changed anything
in the watering regimen the last two months.
Also, (I may be wrong on this) I don't thing light meters for sunlight
accurately read the light coming from flourescents since the
fluorescents only produce a few wavelengths of light (blue GREEN
red)[mostly a green peak plants don't use very well] where as sunlight
has a continuum of wavelenths (rainbow).
Light meters measure light very accurately - if they have been
calibrated. The light readings may not be applicable to what the
plants will think of the light - this has to do with the wavelengths
the plants needs.
I use a 250w sodium light close up with a 75w MH spot 2m away (because
of a silly mounting on my part). I think I will throw the 250 w
fixture out and get a 500w MH one instead because of the yellow light
from the sodium light. Double the wattage will give me about 30% more
light, but it will give a much "whiter" light. It will also allow me
to have the plants more than 10in/25cm from the bulb - I am worried
about the heat from the bulb burning the leaves. I will probably get a
visit from the cops because they think I want the light for growing
pot, but they are welcome to come and have a look.
My one phal is getting 10-15klux, by the way (900-1300fc), and seems
to like it just fine.
Oh, and by the way - I run my lights 16 hours a day in an effort to
get my plants to flower, which means they go on at 5 in the
morning. It also helps me wake up in the morning on my way to the
shower. 250w of light does the work of about a litre of coffee. 
Geir
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