Shedding some light on horticultural lighting
Recently, there has been a tremendous amount of misinformation pervading the discussion about horticultural lighting. Our friends at Kind LED Grow Lights have recently put together some educational resources to help growers make sense of it.
PAR (Photosynthetically Active Radiation):
PAR refers to the spectral range of light radiation within the visible range of light which supports photosynthesis, between 400 to 700 nanometers.
PPF (Photosynthetic Photon Flux):
PPF refers to the total amount of photons within the PAR range produced by a lighting fixture each second. This is expressed in micromoles per second (μmol/second).
PPFD (Photosynthetic Photon Flux Density):
PPFD is a measurement of usable photons which reaches one square meter of a given surface every second, and is measured in micromoles per square meter per second (μmol/m2/s). Whereas PPF is a measurement of the total amount of photons produced by a light, PPFD is essentially a spot measurement.
Efficacy (Photon Efficacy):
Efficacy is a measurement of how effective a grow light is at converting electrical energy into photosynthetically active radiation. This is calculated by taking the PPF value and dividing it by the measurement of wattage (Joules per second). Therefore, efficacy measures exactly how much usable light a fixture produces every second per watt used. (µmol/J)
Full Spectrum vs. Targeted Spectrum LED Grow Lights
Full-Spectrum is a term that has been used in the horticultural lighting industry for years, since the first grow lights entered the market. But what exactly does “full-spectrum” mean?
Full-Spectrum lighting technically means that a light covers all wavelengths of the electromagnetic spectrum that are helpful to plants. However, the term full-spectrum was also used in the 1960s by photobiologist Dr. John Ott to describe electric light sources that simulate the visible and ultraviolet (UV) spectrum of natural light (source), and this seems to be the definition that white-light LED manufacturers refer to when they call their fixtures “full spectrum,” as one thing these fixtures all have in common is that they tend to mimic the look of natural light. Read more here.
White Light LED Grow Lights
White Light LED Grow Lights have exploded in popularity lately, causing growers to wonder what all the fuss is about. White light LEDs are already used in every industry imaginable for human visibility, which speaks to the viability of the technology over traditional lighting methods, but unfortunately, an efficient diode for human visibility is quite the opposite for your plants, irrefutably inefficient, regardless of the specs of the diode. The research and development into white light diodes is much further along—they are readily produced by many large manufacturers, and because of this availability are considerably less expensive than producing diodes with a specially targeted wavelength. This means bigger profits for the companies using these diodes. Often, the efficacy of these diodes is better on paper than the alternatives, which gives the companies the ability to market these specs, despite the fact that efficacy alone does not make a grow light effective. Ultimately, manufacturing white light LEDs is a business decision that several companies have made. Marketing has spun a company cost-saving measure for themselves into a selling feature and in doing so has manipulated a large percentage of growers into believing that it’s the best way to grow. Read more here.
White-light LED companies have recently taken to claiming that above all, efficacy is the most important feature of a lighting fixture, some going so far as to boast the efficacy of a single diode, not the entire fixture. They claim a fixture’s spectral quality is secondary to efficacy, and warn against companies that claim their spectrum is specifically tuned for the benefit of plants. However, this is a false assertion and a deliberate misrepresentation of the numbers to mislead consumers.
Efficacy represents a light’s capacity for turning electrical energy into photons, and is merely a measurement of how many photons within the PAR range a fixture emits per second. But since not all light within 400 to 700 nanometers is used by a plant in equal amounts, a light’s spectrum is vital to the growth of plants. It’s become well known that blue light is the most important part of the light spectrum for vegetative growth, while red light is ideal for the flowering cycle. For this reason, reputable LED grow light manufacturers engineer their spectrum to focus on the parts of the spectrum that most benefit plants, not humans.
White-light LEDs produce a large amount of green and yellow light. While these spectrums play a vital role in plant development, they are effective in considerably smaller amounts than red and blue light. Thus the ratio of light spectrum becomes very important. The amount produced by white light LED manufacturers far exceed the amount a plant can actually absorb, and more than 50% of that light is merely reflected from the plant’s surface, increasing the temperature of the grow environment. Read more here.
We hope this information will prove useful! As always, if you have any questions about your grow, or if you’re looking to get started, please don’t hesitate to call SuperCloset’s amazing Grow Support staff at 877-476-9787, or contact us here! We look forward to helping YOU grow like a SuperPro!