Dank-Dank Try searching for "PAR values". PAR + photosynthetically active radiation usually (but not always) measured in µmols or micro moles. This is in regards to the part of the spectrum that is responsible for plant growth (photosynthesis). I have read that our plants need anywhere from 500 µmol and can handle upwards of ~1800-2000 µmol (the sun is in this range). Hope this helps, -PG