Interesting Owen. Plants don't have a physical coordinating network, aka nervous system like higher animals, so the reception and transmission of information is accomplished through an endorcine like mechanism. Look at how plants resond to injury, temperature variation ad change in day length. While I have never personally read anything about microgravational effects on plant growth and seasonal activation, it may be a factor. The impacts of changing light intensity and duration of light exposure in rural areas on seasonal changes also seems interesting. If there weren't so many factors involved, why do you think there is so much variability in the activation of growth among plants of a particular group across the rang of locations you find them in? And it all does not appear to be simply day length or temperature driven.
Adair, understanding why things work is why we live the way we do now, vs 200 years ago. However, I too think we over analyze things that do work. I frequently ask people who bring this up (fertilizer for example), have you exceeded the capacity of the fertilizer to give you the results you need? Frequently the fertilizer s the last thing we need to look at.