After decades of greenhouse growing, relying on the sun for all of my lighting, I'm now back to "out on the deck" and "windowsill" growing. One aspect of the latter that has bothered me is how much artificial light do I need to add to supplement for that coming in the windows, and I figure I'm not alone, so I put together THIS ARTICLE that shows how 1) if used alone, continuous, artificial light should be one-half the intensity of the historical recommendations, and 2) how to calculate the "volume" of light you're getting naturally, so you can determine the supplementary amount needed.