Horticulture LED Terms to Know

May 30, 2022

Some full spectrum LED grow light terminology you should know.

The technology behind commercial full spectrum LED grow lights is extensive. We have put together a shortlist of essential terms commonly used when referencing LED grow lights for indoor farming.

What is LED full spectrum grow lighting?

LED is Light Emitting Diodes. Full-spectrum LED grow lights are LED lights that mimic the natural sun by giving off a full spectrum of light from UV (ultraviolet) to infrared wavebands (from blue to red).

Plants need a variety of colors from the color spectrum to produce photosynthesis, with red and blue being the predominant colors. Depending on the plants and their growth stage will determine how much lighting and what color spectrum is needed.

What is photosynthesis?

Photosynthesis is the process green plants go through to convert light and carbon dioxide into energy used to grow and develop. The light needed for this process must be in the PAR range.

Using LED full spectrum grow lights will produce the red and blue lighting necessary for photosynthesis.

What does PAR stand for?

PAR is Photosynthetically Active Radiation. PAR is not measured in inches or feet. The light spectrum scale's light wavelength is 400 nm (blue) to 700 nm (red). Plants use the entire spectrum of PAR lighting but at different stages of their growth and for varying lengths of time.

What does NM stand for?

NM is a nanometer (λ). It is how the light wavelength is measured. Visible light is one-billionth of a meter or 400-700 nm.

What does PPF stand for?

PPF is Photosynthetic Photon Flux. All light consists of small amounts of energy called photons. The number of photons emitting from a light source in the PAR range per second is the photosynthetic photon flux or PPF. PPF is measured in seconds (µmols/sec) as it is tiny bursts of energy one after another. A measurement for a large unit of photons of light is called micromole (µmols). These photons are what the plant changes into chemical energy in the photosynthesis process. PPF does not indicate how much light lands on the plants or the surrounding areas.

What does PPFD stand for?

PPFD is photosynthetic Photon Flux Density. PPFD measures the light that lands at the plant canopy in the PAR zone. The light which falls on the plants is measured in micromoles per meter per second (µmol/sm²). The goal is to make sure enough LED lights are placed strategically in the grow buildings to produce the desired PPFD to stimulate the optimum photosynthesis process.

What does µmol/J stand for?

µmol/J is how the efficiency of the PPF and input wattage is expressed. Photon efficacy is how efficient the lighting system is in converting electrical energy into photons of PAR. The higher the number, the more efficient the light is at converting electrical energy into photons of PAR. The µmol/J only tells us how efficient the light is at converting electrical energy into photons of PAR, not how effective it will be on the plants, and it doesn't count light frequencies above 700nm.