I have noticed some people, but not many using foil iver the soil to reflect light back up to the plants. This seems like a bad idea to me, as it would limit airflow across the soil, and down to the roots. However, would it be of any benefit to use a thin layer of perlite on top of the soil to reflect light back of to the bottom leaves? I just though since it is white, it should reflect light back up better than the dark soil. So, viable option, or complete freaking waste?
Interesting idea, but minimal if any benefit from light reflection. Plants can't do much with light striking from underneath, much of the soil is shaded by the plant (or should be), and any light that is reflected has traveled a good distance and so the intensity is greatly diminished. But clear thinking to come up with this, not a whacky idea (like we see so many of)...