Light fixtures with flexible luminaire arrangements and ultraviolet emitters designed to more closely mimic some of the desirable lighting characteristics of natural sunlight. In some embodiment, LEDs emitting in the UVB spectrum are mounted in the luminaire along with LED based luminaires emitting in other emission spectrum. The light from the UVB and other luminaires illuminate plants below to enhance growth characteristics. The UVB luminaires can be mounted in different locations and their emission can be controllable to match the desired plant growth conditions.
