Abstract: Disclosed is a grow light system of any of a variety of modular LED light bars. The light bars may emit light that is heavily-weighted in a red wavelength spectrum, particularly suited for fruiting and flowering growth stages of growing plants, or heavily-weighted in a blue wavelength spectrum, particularly suited for beginning growth stages of growing plants, or in a full wavelength spectrum more closely approximating white light, particularly suited for all cycles of plant life, or any of a variety of other useful light output spectra, or combinations thereof. The light bars may be stand-alone components or combined in a modular fashion. The system may also include a green LED exit sign and/or luminaire emitting light in a limited green wavelength spectrum, providing illumination while not adversely affecting plant growth during dark cycles. The light bars may be suspended from an adjustable rectangular frame.