Light requirements vary from species to species and they even vary within the species themselves. Lumens measure light intensity whereas light spectrum measures wavelength.
I've always wondered what triggers some plants, such as plumeria, to drop leaves even when the temps don't change much and the hours of light are fairly close as well. Now I wonder if it isn't the change in wavelength, even here at 20° lat I assume that the light moves more towards the blue in the winter?
