Flourescent Light Advice

[consettbay2003]

I would like to know what Kelvin reading (colour temperature) tubes other 'under light' growers would recommend for optimum paphiopedilum growth.

 

[luvsorchids]

I grow under T5 fluorescents using 48 inch 4-bulb fixtures. I use 2 warm and 2 cool bulbs in the fixtures and seems to work just fine.

Susan

 

[Ray]

Something in the neighborhood of 6400°-6500°K is intended to match the spectrum of direct sun plus the back scatter of a clear blue sky. Not so coincidentally, that spectrum also matches most closely the absorption of the chlorophylls and the carotenoids that energize them in the photosynthesis process.

I think it's doubtful that boosting any part of the spectrum will add much, or "force" anything significantly, but it cannot hurt as long as the entire range is provided.

I speculate - and that's all it is - that back in the old days, when fluorescent phosphor technology was not as advanced as today, it was necessary to mix "colors" in order to span as much of the required spectrum as possible, and that what we're seeing is a carry-over from that, even though it may not be necessary.

 

[Justin]

i alternate daylight with cool white bulbs 1 each in every fixture.

 

[Silvan]

what type of paph you're growing? My parvis bleached out under T5( daylight 54watts HO 6400k)), but under 4 cool white (T12 40watts), they've greened up.. but I'm no reference as they aren't flowering

 

[Ray]

what type of paph you're growing? My parvis bleached out under T5( daylight 54watts HO 6400k)), but under 4 cool white (T12 40watts), they've greened up.. but I'm no reference as they aren't flowering

Have you considered increasing the distance to the bulbs? "Bleaching" is often due to excessive light intensity levels, not a spectral thing.

 

[consettbay2003]

I believe Ray is spot on with his distance to the bulb comment. T12 fixtures (40 watts) can be positioned relatively close to the leaves but with a T5 fixture this would be catastrophic. This would damage/destroy the chlorophyll resulting in 'bleaching'. T5 bulbs put out quite intense light and my supplier recommended hanging the fixtures (4 bulb - 19,200 lumens) approximately 1 meter above the plants. I have been getting excellent growth at this height. I have a specialist light meter for flourescent bulbs and get a reading of approximately 700 fc at this height. I realize some growers would feel that this light level is too low but with continuous illumination at this reading it is more than sufficient.

 

[Silvan]

My ceilling is too low to be able to move the height of the bench or fixture, so it was easier to just move my plants.. I too believe in the power of continuous illuminating



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[Erythrone]

I am suprised to read about continuous illumunation. Do you do this for all your orchids????

 

[Silvan]

I meant 14-16hours per day every day..not 24/7 sorry for the misunderstanding
..I meant too that even with lower light level you still can manage to flower plants.. but in my experience some plants (mostly phrags) won't get as nice of foliage as if it was growned under higher output.

 

[Paphluvr]

When I was growing under lights my large bench had four 8' HO tubes above it (two Growlux WS and two cool whites). That's 440w of power that I kept 6-8" above the plants for 14hrs/day and never had a problem with bleaching out the plants. Bloomed a Paph parishii with this setup that took "Best of Show" in Toronto years ago with 8 flowers on the spike. I think if you keep good humidity and airflow you shouldn't have a problem