Seeking the optimal LED grow lights for your indoor cultivation endeavour? Investigating the subject may become daunting, resulting in greater confusion than initially experienced. Specifications for grow lights can become quite complex, detailing expected wattage, lumens, PAR, or PPFD. This tutorial elucidates the seemingly daunting ratings and clarifies their significance.
Upon grasping the essential metrics of grow lights, you will be much more adept at selecting the optimal lighting for your initial vegetable garden or a compact grow light for your indoor plants; the possibilities in indoor horticulture are limitless.
What constitutes light?
It is time for a brief review of scientific concepts. Note that not all light is perceptible; light is just a minuscule fraction of a category of energy, commonly referred to as electromagnetic radiation. This radiation encompasses gamma rays, microwaves, radio waves, and X-rays.
visible radiation throughout the electromagnetic spectrum
Distinct wavelengths and frequencies, quantified in Hertz and nanometres, characterise these various forms of electromagnetic radiation.
The Varieties of Light: Visible Light Compared to PAR
Visible light comprises wavelengths perceptible to the human eye, often ranging from 380 to 700 nanometres. Any wavelengths above this range are imperceptible to humans; but, several species possess the ability to see higher or lower wavelengths. Significantly relevant to our discourse, plants possess the ability to perceive light beyond the visible spectrum. Certain plants can perceive wavelengths ranging from 260nm (UV-C) to 730nm (far-red).
Visible spectrum
Most of the light used by plants for photosynthesis resides within the visible range (400-700 nm). This spectrum of solar radiation is referred to as photosynthetically active radiation (PAR).
This PAR range approximately aligns with the spectrum of visible light perceivable by the human eye. The primary distinctions are that plants exhibit heightened sensitivity to red and blue light, whereas the human eye is more responsive to green and yellow light.
What is the significance of this?
Grow lights that seem luminous to humans may be less beneficial to plants, particularly if there is an excess of yellow light. This understanding elucidates why several grow lights use red and blue diodes in their composition.
Having established the many forms of light and their subtle distinctions, we must now determine the methodology for their measurement.
LUMENS FOR HUMANS
Historically, human-centric lighting was assessed by quantifying the radiant flux (power), defined as the total visible light in Watts (or J/s). Despite the prevalence of LEDs, we continue to characterise lights by specific wattages, referencing traditional incandescent bulbs (40W, 60W, etc.).
This meter is obsolete and deceptive, as light power numbers may rise with increases in non-visible radiation. A light source emitting substantial quantities of violet and red light may exhibit a high overall radiant flux. Nevertheless, because to the human eye's heightened sensitivity to yellow and green, the light would appear significantly weaker compared to a similarly powered light that emits greater intensity in the green and yellow wavelengths.
In 2022, luminous flux (quantified in lumens) serves as a significantly more relevant parameter for assessing light brightness. It resembles radiant flux but is adjusted based on the sensitivity of our eyes to green and yellow light.
Luminous Flux inadequately depicts the red and blue wavelengths, which are essential for plants, and serves as an ineffective measure of light's utility for them.
Luminous flux or brightness ratings are not effective marketing points for grow lights. Exercise caution about other lumen-based metrics such as lux, foot-candles, and candelas. These are beneficial for human uses but ineffectual for horticulture, serving just as a point of reference.
Shenzhen Benwei Lighting Technology Co., Ltd was established in 2010. It is a national high-tech enterprise integrating design, R&D, production and sales of indoor and outdoor lighting products and also can do OEM ,ODM .For more details about our offerings, please contact us at bwzm18@ledbenweilighting.com
