Quote Originally Posted by WashougalWonder
I have often wondered why we narrow down the light band for flower. (The sun never really has a different light band does it?)
From what I gather, the sun is in a different position in the sky in early summer, than it is in the fall. Different sun-angle through our atmosphere alters the spectrum giving the plant not only daylength and temperature indicators to upcoming winter, but light spectrum clues as well.

I heard this years ago, and never investigated the issue further. Kinda made sense, but I'm no expert. :thumbsup: