LED UFO lights

[terryros]

I am in it whole hog with LEDs in my indoor plant room. I have been using LEDs completely since December, 2010; 300 watts of LEDs instead of 1,500 watts of fluorescents. I use "natural white" bulbs under which everything looks natural. I, and others purchasing lights from Orchids Limited, are being successful with growth and blooming. I need plants and flowers to look natural. The main advantages for me are gaining headroom over the plants and temperature control in the plant room.

[DavidCampen]

Originally Posted by terryros

I am in it whole hog with LEDs in my indoor plant room. I have been using LEDs completely since December, 2010; 300 watts of LEDs instead of 1,500 watts of fluorescents. I use "natural white" bulbs ... from Orchids Limited... .

Which lights are you using. I looked at these lights that are being sold by Orchids Limited and at 65-75 lumens per watt they are only about as efficient as T-8 fluorescents:
Orchid Web: LED Grow Lights T-100
http://www.orchidweb.com/altpdf/alt_t100_t150.pdf
http://www.allenelectric.com/doe-lig...gs-eff2012.pdf
LED Lumens Per Watt: Should I be Concerned About Switching from T8s? | Green-Buildings.com

[DavidCampen]

A comment that I should make is that lumens is a very poor metric for comparing the efficiency of plant grow light sources.

The lumens metric is intended to give a comparison of how bright light sources would appear to human vision. As such lumens is calculated as power at each color multiplied by how sensitive the human eye is to that color. The eye is most sensitive to light with a wavelength of 555 nm (green) but plants find 555 nm light to be photosynthetically relatively useless. So if you had 2 light sources each emitting the same amount of power but one at 555 nm and the other at 460 nm then the light source at 460nm would have only 1/16th the lumens of the 555 nm source but the 460 nm source would be providing much more power to the plant for photosynthesis.

The reason that white LEDs and fluorescent lamps can be somewhat compared by their lumen ratings is because they have about the same spectral power distribution.

When you start talking about LEDs that emit monochromatic light in the blue and red then lumens is useless for comparing those light sources to fluorescent lamps or white LEDs.

But most people are interested in knowing how effective a light source is at providing illumination so lumens is about the only metric that is commonly available.

[terryros]

I agree. We care about the lumens of the correct wavelength delivered to the growing surface. With fluorescent lights, even with the best reflectors, a lot of light is lost into the room and doesn't get to the plant surface.

My experiment is really to run a whole year so that I can see the full growth/blooming cycle of plants. But, the main advantages to me of the LED lights is not to get superior growth compared to other lights, although that could happen, but I want to be able to have the lights much higher above the plants and still get good illumination, something you can't do with fluorescents. I also wanted less heat production in my room and less energy consumption so I wasn't blowing the circuit breaker all the time when I would forget to turn off lights so I could run my watering pump? All of these have been achieved. I can only report on about half of years experience and say that things are growing and blooming. The lights I am using also give a natural coloration to plants and booms, something else that I wanted.

[naoki]

Originally Posted by littlefrog

Well, I'm going into it whole hog, so I'll probably be posting stuff in a few months about setups and stuff. Actually half hog, I'm going to do about half LED and half fluorescent (T5).

Rob

So Rob, is LED working well with your orchids? Which light do you use?