Wrong Spectrum

The following are selected quotes indicating what effects color of light (spectrum) and quantity of light have on plant growth. Paul Krombholz states:

Light intensity, spectrum:

I did say that blue light promotes shorter, bushier growth, while red light promotes taller, lankier growth. This wasn't an original statement on my part though, it's pretty well documented in horticultural literature. I didn't say anything about leaf size. The trouble is that people have taken the above statement to mean that you can (should?) emphasize one end of the spectrum over the other. What I was trying to get across (and obviously failed, since this has come up numerous times) is that with our present knowledge or lack thereof, it would seem prudent to provide good balanced coverage at both ends of the spectrum.

As far as long internodes and small leaves, in my experience, this is most likely a sign of inadequate intensity, rather than the "wrong" spectrum, what ever that is.

Offered by Mike.