Crop growth in controlled environments can be improved with targeted strategies to deliver supplemental light. Three studies evaluated elements that can affect photosynthesis and growth. Study one used chlorophyll fluorescence to quantify the daily photochemical integral (DPI, electron transport rate integrated over 24 hours). Daily photochemical integral increased when the same daily light integral (DLI) was provided over longer photoperiods at a lower photosynthetic photon flux density (PPFD) for Lactuca sativa grown in a growth chamber. Study two applied these findings to greenhouse production using an adaptive lighting control system. Supplemental light-emitting diode (LED) arrays were provided to achieve a similar target DLI across set photoperiods. Supplemental light increased growth of Rudbeckia fulgida seedlings more efficiently at longer photoperiods and lower PPFD. Study three evaluated supplementation with far-red light on growth of Digitalis purpurea seedlings in a growth chamber. Plant dry weight increased with increasing far-red without detrimental morphological effects.