 The study investigated growth, photosynthetic performance and nitrogen status in leafy herbs grown under different light spectra emitted by LEDs using fluorescence-based sensors to detect crop and status and maximum photochemical efficiency of photosystem 2. For light treatments including dominant red light and or white LED lights at 200 mole M2S1 at plant level provided the most favorable conditions for plant growth and development while a high proportion of blue light resulted in higher chlorophyll index and nitrogen balance index, NBI, than under dominant red light treatments. The study highlights the potential of fluorescence-based sensors in photobiology research as well as in the production of leafy herbs under LED lights. This article was authored by Bozina Matysiak and Artur Kowalski.