One thing that I didn't quite catch from this was whether or not the fertilizers are absorbed entirely through the stomata or if they can be absorbed directly through the cell walls on other parts of the leaves. If they are absorbed entirely (or nearly entirely) through the stomata, one would benefit greatly from focusing spray on the undersides of the leaves rather than the whole plant. If I'm not mistaken the undersides of the leaves hold the majority of the stomata where the spray will be absorbed. I would think it would be best to spray late in the day. The closer to dusk the better. Not only do more stoma open at night when it gets cooler, but the last thing you want is to burn your leaves with the little droplets. They act like little magnifying classes and we all know what sunlight can do to ants