Plant Grow Lights: HPS, Metal Halide, Fluorescent and LED

Plants it uses light to drive the photosynthesis process and grow. Although natural sunlight is the best light to support plant growth, artificial light sources are needed in environments with insufficient or no sunlight.

Traditionally, high pressure sodium (HPS), metal halide and fluorescent lamps are used in the plant lighting system. Such light sources have a low efficiency. LEDs, on the other hand, have high efficiency and long service life. For this reason, LED-based plant lighting systems are rapidly replacing traditional lighting solutions.

When talking about the efficiency of plant lighting systems, it is possible to make two different definitions as spectral efficiency and energy efficiency.

The wavelengths of light in the range of 400 to 700 nm stimulate photo pigments in plants, making photosynthesis possible. Not all wavelengths of light are equally effective at directing plant photosynthesis. Red and blue light are the strongest colours to support plant growth. Green light, on the other hand, has a very limited effect. It has poor spectral efficiency as its high pressure contains significant amounts of photosynthetically inactive light such as sodium, metal halide and fluorescent lamps, infrared radiation (IR) and ultraviolet radiation (UV). LEDs, on the other hand, provide more spectral control possibilities than conventional lighting systems. The light spectrum of LEDs can be easily customized to support plant growth. LEDs can be configured to emit more red and blue light and less green light.

The energy efficiency of lighting systems in the plant growing industry is expressed in terms of PPF (Photosynthetic Photon Flux) per Watt. PPF refers to the total amount of photosynthetically active photons produced by a light source. LED grow lights have a photon efficiency of 3 PPF/watt, while HPS plant lights have an average photon efficiency of 1.5 PPF/watt. This means that power consumption will be halved if LEDs are used instead of a lighting system using HPS. On the other hand, space can be saved by using smaller lighting equipment.

LED technology is the most energy and spectrally efficient lighting technology for grow lights. World-renowned LED manufacturers such as CREE, OSRAM, SAMSUNG and LUMILEDS produce special solutions for grow lights.