White LEDs vs. Full Spectrum (Multi-Band) LEDs
The time has come for us to face a monster that has plagued LED forums for years... let it be known that on this day, henceforth, the myth has been shattered and the riddle answered: Which is better, pure white light ,or the holy grail of “Full Spectrum”? Throughout the generations of LED Grow Lights, this demon has been one of the biggest. Join us as we dissect this beast! We'll cover both sides and attempt to find balance and achieve solidarity.
What Does 'Full Spectrum' Mean?
Even a cursory googling of "Full Spectrum LED Grow Lights" will undoubtedly reveal 4.5 Million results, but what does it really mean? For clarity's sake, 'full spectrum' is a consumer word - NOT a scientific one, and it refers to any light that emits the full range of visible light from far red down to deep blue. Taking the long view, so-called Full Spectrum LEDs are merely one of the stepping stones on the path towards creating the 'perfect' sun-like LED grow light; indeed, light designers have been tweaking and broadening their spectrum since the moment someone thought to shine an LED on a plant.
"Full Spectrum LED is a Consumer Word - NOT a Scientific One"
Initially, manufacturers employed a two-band system using just red and blue, as two carefully tuned wavelengths alone were (and still are) capable of growing a plant; as the LED technology evolved, more bands of light were added to cover different shades of red and blue, orange, amber, UV, and more.
Nowadays, features like '12-band spectrum' and 'proprietary 6-band spectrum with UV' have become the norm. However, we must watch our consumerist tongues when uttering "full-spectrum!" Often, some wavelengths are nearly or completely absent, thus negating the 'full' portion of their titles. It would be more accurate to refer to these lights as “broad multi-band spectrum” LEDs because it more accurately describes the spikes and dips in their wavelength emittance. What do you think? Take a look at that little graph. You can usually spot a broad multi-band light by its purple haze.
Why Use Full Spectrum Instead of White?
Here's why some people claim that 'full spectrum LEDs' are better than white LEDs.
Quick Answer: Blasting plants with every wavelength at full bore is overkill – like kicking a rhino's junk in a nuclear wake while shredding like Joe Satriani. Meanwhile, using a surgical and technical approach with targeted full spectrum wavelengths allows growers to grow more efficiently and increase their yield weight per watt... of course, its important to reiterate that the science behind these claims are only exceeded by the strength of the opinions the full spectrum advocates have.
Long Answer: Sorry, LED Heads, we're going to have to science the $#%7 out of this; If you don't want to bruise your thinkin' parts, fast forward down to "Why Use White Instead of Full Spectrum" by clicking what you're reading now. Otherwise, roll up your sleeves... Plants don't need a fully maxed out light spectrum of blindingly white light because photosynthesis does not require it. Photosynthesis is a process that has been in the works for billions of years and plants have taken their time to figure out exactly what works best for them. Science has allowed us to understand the major mechanisms that make plants tick. Here's a handy chart from Lush Lighting that depicts what we're talking about.
This is no child's play and actually only covers a portion of the complexity inside of plants, but let's take just a second to define what we're looking at. There are 5 different colored lines which represent the protein/pigments that drive the process of photosynthesis in plants. Let's examine them in two groups: The primary drivers of photosynthesis and secondary support.
Chlorophyll A and Chlorophyll B are the chief engines that convert light energy into to sugar, which is fuel for the plant. Found mainly in leaves and stems, chlorophyll is a green pigment that absorbs mostly red and blue light while reflecting green light; they're the reason plants appear to be green! There are two types. Chlorophyll A sensitivity is depicted by the light blue line in the chart above. It is arguably the most important driver of photosynthesis as it very efficiently converts light into energy for the plant. It is mainly sensitive to spectral peaks at blue 430nm and red 660nm. The reason red lights so effectively grow a plant is thanks to this protein. Thanks Chlorophyll A! Chlorophyll B is sensitive to spectral peaks at 460nm and 630nm. It mainly absorbs blue lights and actually serves a support function to Chlorophyll A by donating energy - it could really be grouped with our next protein pigments...
These protein pigments pick up the slack where Chlorophyll cannot by absorbing other wavelengths of light. However, they are 'secondary' because they do not directly convert sunlight into sugar; they are accessories to chlorophyll and contribute to growth by passing the energy they 'collect' along to the cholorophyll. There are two groups: 'phycobiliproteins and carotenoids' (say that three times fast... or even just once.) Let's take a glance.
Phycoerythrin's peak reactivity is found at roughly 495nm and 575nm. It absorbs absorbs slightly blue-green/yellowish light and appears slightly orange-yellow light.
Phycocyanin is a characteristic light blue color, absorbing orange and red light around 630nm (depending on which specific type it is.)
Carotenoids are orangish proteins reactive to bluish light, and play an important support role in photosynthesis. In addition to donating their energy to chlorophyll, they also serve as plant protectors by absorbing the oxygen byproduct produced during photosynthesis. There are two distinct peaks around 440nm and 470nm with high absorption between them.
"Full Spectrum LEDs are Cleaner, Greener, and Save you Green - At Least That's the Idea."
So, what were we talking about again? Oh yeah! Multi-band broad spectrum lights are the best because they can pinpoint the wavelengths we just mentioned. While white light uses a broadsword tactic of brute force, full spectrum LEDs are cleaner, greener and save you green - at least that's the idea. They save energy and thereby money by making ONLY what the plant needs.
Why Use White Instead of Full Spectrum?
Remember that spiky rainbow graph way above that depicted a 'full spectrum' light from before? All of those gaps and deficiencies may not hurt your plants, but they may not be optimal either. Our goal as green thumbs is to give our plant what it needs; plants love the sun, so if we can replicate the sun, we should. Through extensive scientific research, we now have found what is considered to be an ideal balance of wavelength - it is called a McCree curve. This curve shows us the average plant's photosynthetic response to light: smooth, full, and certainly not spiky; we should set our aims towards this curve. Hmmm... how could we replace those spikes that are so common in 'full spectrum' LEDs?
White light is closer to natural light than the spikey result from multi-band. White light also is free from a few issues that plague 'full spectrum' LEDs, namely two problems: poor color-mixing and banding. Color mixing is when one part of a plant gets a different ratio of color than another; for example, one leaf getting too much blue while another gets an overdose of red. Banding is when there are different 'bands' of color or light strength.
"White LED Lights Can Grow Your Plants from Seedling to Bloom Without a Second Thought, but.."
Furthermore, the final nail in the coffin is that white LED light can grow your plants from seedling to bloom without a second thought, but when we using full-spectrum lighting, we need to consider growth cycles and cycle switching, adding another unnecessary level of complexity to growing.
Perhaps the next step in LED 'full-spectrum' lighting is the COB (Chip-on-Board) which have the advantage of thermal resistance, a larger cooling area, better lighting effect, and higher light efficacy than before. The COB combined with parabolic reflectors will help blend the light to reduce the banding and improve color-mixing issues experienced with other full spectrum LED lights. Some brands that are already employing this technology are Gehl and Hydro Grow (Sol Series.)
The final point to consider is that perhaps neither one is better than the other and that joining forces is really the best alternative. Many manufacturers have been experimenting now with mixing white diodes in different ratios and combinations with red, blue, UV and more to look for something that will grow every type and strain of plant at near-optimal levels from the get go. Expect to see more white + full spectrum lights hitting the market in 2017. Until then, chow down on this list of brands by spectrum, and keep your peepers peeled for our next LED Head Feed article!
|Kind LED||California Lightworks||Next Light|
|Hydro Grow||(More Soon!)||BIOS|
|Black Dog LED||ProMax Grow|
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