High Intensity Discharge Lighting

High Intensity Discharge (HID) lighting refers to a category of artificial light sources that produce illumination through an electrical discharge between electrodes in a gas-filled bulb. Common HID types used in cannabis cultivation include Metal Halide (MH) and High-Pressure Sodium (HPS) bulbs, each emitting distinct spectral distributions. MH bulbs typically produce cooler, blue-spectrum light often associated with vegetative growth phases, while HPS bulbs emit warmer, red-spectrum light frequently linked to flowering stages. HID systems require ballasts to regulate electrical current and have been a foundational technology in indoor growing operations for decades, though LED technology has increasingly competed in this space.

Breeders and cultivators working with HID systems evaluate strain phenotypes under these specific light spectra to assess growth vigor, internode spacing, and flowering response. Documentation of how particular genetics perform under MH versus HPS conditions helps inform breeding selections and cultivation protocols for indoor production.