[justa-hairyape]

If those are actually LEDs he did nothing special about the light spectrum. It is cool white. He did no research on LED spectrum emission. My guess is he is not using much LED. Maybe for seedlings.

[thackney]

I buy industrial LED lighting.

You can get a broader light spectrum than the basic white LED of years past.

http://www.seesmartled.com/kb/choosing_color_temperature/

http://www.ledsmagazine.com/articles/print/volume-8/issue-4/features/precise-led-wavelengths-spur-plant-growth-magazine.html

[thackney]

Far more information than either of us want to know about the success of LED lighting for plant growing:

http://www.usa.lighting.philips.com/pwc_li/main/shared/assets/downloads/pdf/horticulture/leaflets/general-booklet-philips-led-lighting-in-horticulture-USA.pdf

With LED lighting, the growth light – spectral output – can be tuned, which makes it possible to apply the optimum ‘light recipe’ at every stage of a crop’s growth.