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What is PAR (Photosynthetic Active Radiation)?

  PAR refers to the range of light within the light spectrum that plants use for photosynthesis. This spectrum spectrum ranges from 350 nm to 650 nm. 

Understanding PAR Measurements

  While PAR is often mistakenly referred to as a measurement of usable light, this term really only refers to a type of light. To understand how much PAR an LED grow light emits, look to measurements such as PPF and PPFD. PPF (Photosynthetic Photon Flux) communicates how much PAR a light emits. PPFD (Photosynthetic Photon Flux Density) measures the amount of PAR that reaches the canopy.