What to do about lights for orchids?

[raybark]

While the plants those "selectable spectrum" fixtures - cannabis - may very well respond to spectra changes, that doesn't mean all plants do.

All of my under-lights growing recently is under white LEDs that hthe as been supplemented with a bit of red. They are sold as Production Units by Philips. However, based upon some work by Naoki Takebayashi at U of Alaska-Fairbanks, I am now pretty well convinced that a good quality white LED with sufficient true wattage (not "equivalence") would work. Yes, chlorophyll and other alkaloids may better absorb certain wavelengths, it appears that photon count may be more important, as long as some spectral spread is provided.

I purchased some (18 watt?) Cree outdoor floodlights for the fixtures over my driveway that are REALLY bright, and not all that expensive, so if I find I need to light up more plants, I'll definitely use those.

[sciencegal]

“If we could see the miracle of a single flower clearly, our whole life would change.” - Buda

Buddha is the correct spelling.

---------- Post Merged at 07:43 AM ----------

While the plants those "selectable spectrum" fixtures - cannabis - may very well respond to spectra changes, that doesn't mean all plants do.

What I found interesting when looking this up is that some LED manufacturers state the efficiency of their lights in terms of "grams per watt".

[raybark]

What I found interesting when looking this up is that some LED manufacturers state the efficiency of their lights in terms of "grams per watt".

That's hilarious!

[Dorsetman]

First ; when I was building my paph collection some thirty years ago I had to raise everything from flask, and I used a dew-point cabinet where the plants were lit by 2 foot fluorescent tubes. Not cheap - about US$500 even that long ago,( it was not US made - I have converted to ease understanding ) but the growth rate in there was approx. 3 times as fast as by any other route - that's where I got paphs to flower 22 months from deflasking in the best cases . The makes said "change the tubes every six months - you won't see any difference with human eyes but the light spectrum will have changed due to ageing of the coating on the inside of the tubes". I always followed that advice.
Second, nowadays for adult plants - my cattleyas in particular, I use metal ballast 600 watt dual spectrum lights, mounted on light-tracks so that they shunt back and forth over the plants ; that way they are so low that the reflector just brushes the top of the leaves, but I avoid burning because of the movement. Each lamp lights a bench about 3 feet wide and 15 feet long. The results can be seen in the cattleyas I have been showing recently.

[Regelian]

OK, I'm going to just jump in here, as LEDs are a part of my research.
First, plants (all photosynthysising organisms, actually) require light in the red (660nm-720nm) and blue (420nm-460nm) spectrum for most of their work. Other parts of the spectrum may be utilized by other photopigments, but chlorophyll is the main photopigment providing well over 90% of the energy in a plant and this is where they function.

LEDs come in various colours and Royal Blue plus Far Red are the typical colours involved in commercial fixtures. LEDs are not rated in Watts, so forget this old reference. They are rated in their efficiency level. Generally as lumens per Watt at a specific 'drive' level (Amps x Volts). This is variable and the best LEDs, such as from Cree or Phillips (Luxeon) use these ratings. The cheap (less than 1 Watt rating) LEDs are close to useless for plants, due to their poor efficiency. They simply consume too much to produce a usefull amount of light compared to cost.

that said, some of the inexpensive fixtures may prove usefull as a supplmental lighting. Still, if you are serious about creating a good lighting scheme for your orchids, ivest in the best fixture you can afford. It will consume less energy, produce better light and last about 10 years!

Hope this helps a bit in understanding LED lighting.

Jamie V.