Are White LED Lights Good For Growing?
Last updated March 1, 2020 By Steven Leave a Comment
It just keeps getting more confusing.
First we were told that plants want red and blue light, because other wavelengths, like green and yellow, are not absorbed during photosynthesis.
Giving your plants white light, which contains a lot of green and yellow wavelengths, means paying for a lot of light that simply goes to waste.
We were told that is why LED fixtures with red and blue diodes are more efficient. You are not wasting money on electricity to create light that plants don’t even want.
And it made sense.
But now we are being told the opposite. That full-spectrum white light is, in fact, better.
And it makes sense too.
So what’s the truth? Is white light any good for growing plants?
Short answer: it is. It is better than LEDs that have only blue and yellow light.
And by adding additional diodes, we can make it even better. But before we get to that, let’s take a closer look at what a white LED light actually is. Because it’s not white.
What Is A White LED?
Let me explain what I mean and clear up a misconception at the same time. White LEDs aren’t actually white.
The first “white” LEDs were actually a red, green and blue LED packed into a single diode. Mixing these three colors together leads to white light. Altering the proportions of each gives different color temperatures.
This same combination of three LEDs, often with a fourth added in to flesh out the spectrum, is still used today for some applications. But it is not the way the “white” diodes that we see in grow lights are made.
Using three differently colored LEDs together is obviously not the most efficient way to create white light. For that reason, another method was developed that only uses a single LED.
These LEDs used the same principle that was already in use with fluorescent lights. Fluorescent tubes actually produce ultraviolet light, not white light. A powdered coating on the inside of the tube coverts this UV light to red, green and blue light. And, as mentioned, the combination of those three colors appears white.
LEDs that emit an ultraviolet or violet light, which is then converted to white light by a phosphor coating on the lens or other enclosure, is called a full-conversion white LED. These work, but they are not efficient.
That spurred researchers to try and create a partial-conversion LED. These use blue light instead of UV and the phosphor coating converts part of that blue light to a yellowish light (made up of red and green). That yellow combines with the remaining blue to create white light.
Since only part of the blue light is converted (as opposed to the whole UV light), this type of diode is much more efficient.
And the efficiency has continued to increase to the point where white LEDs are now the most efficient lights on the market. Especially ones with added colored light, but we’ll get into that in a minute.
White LED Spectrum
When these phosphor-coated diodes were first introduced, the spectrum was fairly narrow. But the use of difference phosphors and different blue wavelengths led to ever-broader spectra.
If you look at the spectrum of a popular white LED grow light, you can see that today’s white LEDs give you a true full spectrum light with output at every wavelength.
Color spectrum of a 3500K white LED
What Is The Wavelength Of White LED Diodes?
As you can see from the spectral chart above, today’s white LEDs emit light in every visible wavelength. How much of each wavelength they give you depends on the color temperature of the light.
For example, a cool white light, like one with a color temperature of 6500K, contains more blue wavelengths. A warmer white light, like one with a color temperature of 3000K, contains more red wavelengths.
How do you alter the color temperature of a white diode?
It is simply a matter of using a thicker phosphor layer and altering the wavelength of the blue LED beneath the phosphor coating. Modifying these two variables allows manufacturers to change the color temperature of their LEDs.
Let’s take a look at some of the more common color temperatures and see how they compare and when you would want to use them.
2700k Vs 3000k For Flowering
Lower color temperatures mean a warmer white light and warmer light contains more red wavelengths than cooler light. As a result, these color temperatures are great for flowering.
When it comes to LEDs, you generally find either 3000K or 3500K. 2700K is not common in LEDs, but is the color temperature of many HPS or CMH bulbs.
The lower color temperature (2700K) is better for flowering, but if you are using your light for every stage of growth, you would be better with something slightly cooler, like 3000K or 3500K.
5000k Vs 6500k For Plants
Both 5000K and 6500K white light is great for growing plants, but not as great for flowering them. It will still work fine, but a warmer color temperature would work much better.
As a result, I would only recommend cool LEDs like these if you are vegging and nothing else. If you will also be using the light to flower, you want a color temperature of 4000K or lower. If you are vegging only, then 6500K light is better than 5000K, though both would work great.
5000k LED For Veg
5000K light contains more red than a 6500K light. Red light actually helps a lot during vegging too, but since the cooler light also still contains quite a bit of red, it is better if only vegging.
6500k LED Light
6500K LED light is definitely a vegging specialist. If you plan on doing nothing but vegging or cloning, then a cool light like this is ideal.
Are White LED Lights Better At Growing Plants?
That brings us back to our original question. And the answer is a resounding “yes.” White LED lights are great for growing plants.
But isn’t it true that plants want mostly red and blue light and that green and yellow light goes unused?
Doesn’t that mean that white light is less efficient than a “blurple” LED?
As we’ve been learning more about the effects of different colors of lights on photosynthesis, we have come to realize that green light is not as useless as we thought.
Green light actually penetrates deeper into the canopy of plants than other colors. This means that a fixture with a healthy amount of green will stimulate growth further beneath the canopy than a light that does not contain green wavelengths.
In the end, white light has a great effect on plant growth. Because it contains a lot of green wavelengths, it results in stronger growth. It also results in great yields, if it is a warmer white light with a healthy amount of red wavelength light.
And if you add additional red diodes to the mix, you get a light that flowers even better. This is exactly what many of the most popular LED manufacturers are doing these days.
If you look at the best LED grow lights on the market today, they all use mainly white diodes (in some cases COBs). But they no longer use only white diodes.
Depending on the brand, they add in various additional colors: some add deep red only, some add deep red with infrared and UV, some also add some blue to the mix. Some of them only have a few additional diodes, while others have a lot. Specifically:
- Phlizon adds a bunch of extra light that is primarily red and blue, but also UV, IR and even additional white diodes.
- HLG adds deep red.
- Spider Farmer adds deep red and infrared.
- Kingbrite has a bunch of different options, but their most popular lights add deep red, IR and UV.
- Maxsisun adds deep red
- Mars Hydro TS/SP lights have additional deep red, plus UV and/or IR, depending on the fixture
All of those brands offer fixtures that use mostly white LEDs. Since the industry is moving in this direction, it should come as no surprise that these are also some of the most popular brands on the market today. And they are ones that give incredible results that outdo the equivalent HPS lights.
White LED lights are simply better and they are taking over as a result.
First we were told white LEDs are not as good as red and blue ones, but now we are being told that may not be true. Which is it? Find out why white LEDs are actually…
Are White LED Grow Lights Good for Growing?
For people who love to grow indoor plants, there are always continuous debates on the best grow light that gets the best results for growth. One of the most recent debates is the effect of white LED lights on indoor plant growth.
University Studies Show White LED Grow Lights are Better than Purple:
A study at Chiba University measured the effects of supplemental lighting with LEDs on tomato yield, which included white LEDs.¹
Based on the unit photons emitted, the white LEDs showed as high efficiency as the red LEDs in increasing tomato yield, followed by the blue ones.
This is quite an interesting result because not many grow lights include white spectrum, although some of the higher end models have started to include it.
The study found that tomato yields increased 12 to 16% when white LED lights were included with a mix of red and blue lights to grow tomatoes.
Even though the red and blue lights contributed to the result, the study’s authors concluded that “The results were probably due to the white LEDs that contained more than 50% of green light characterized by high penetration into the canopy.”
A second study observed lettuce grown using only red blue spectrum compared to lettuce grown using red blue plus white spectrum.² The study found soluble sugar and nitrate contents in the lettuce grown with added white spectrum was significantly higher and lower, respectively. If you’re wondering – that’s exactly the result you’d want.
Researchers also observed higher shoot and root fresh and dry weights as well as higher crispness, sweetness, and better plant shape for the lettuce grown using white light.
What is White Grow Light Spectrum, Actually?
While most indoor growers are familiar with the benefits of using purple growing lights, white LED lights are a newer consideration.
Almost all growers have previously considered white light to have little or no value for plant growth. However, this is not actually true with white LED Lights, as seen in the studies cited earlier.
The white light spectrum includes a few colors currently included in all LED grow lights, like blue and red. But it also comprises of a few wavelengths not included in significant intensity in most LED grow lights today.
The full white light spectrum can be seen in the table below:
Most LED grow light spectrum charts will already show these wavelengths, but the intensity of the wavelengths other than red & blue is weak. Below we linked to a brand of more modern grow lights that includes a full white spectrum, including the all important red and blue as well.
White LED lights are also great lighting to help enjoy the plants as they grow, and they provide a 40% light absorption rate. Additionally, because they are LED, these lights will not burn or over chafe the leaves, ground or soil with a drying light.
What Color LED Is Best For Plants?
While there are a host of different grow lights produced, there has not been enough discussion of the benefits of using white LED grow lights for plants.
With that said, the studies cited above prove that white spectrum LEDs are best for plants.
Traditional high intensity bulb lamps are not as effective because they use more energy and the light released is lower quality. The spectrum produced by HID lamps (HPS and CMH) are usually heavy on red or blue and nothing else.
The use of high intensity bulbs for growing can create a hot environment that’s hard to control. This has often been a significant complaint from indoor plant growers.
Because of this, an increase in plant light analysis was done that included the use of white LED lights. Part of the desire to compare white LED lighting for plant growth came from their low energy use and ability to stay in use for longer periods of time safely.
Based on the studies above, we conclude that more high quality grow lights should include white spectrum. In fact, many are starting to do so.
Which Grow Lights Utilize White LEDs?
The Mars Hydro TSW 2000 is a modern, low price range quantum board grow light that has an intense white light spectrum. This light is the best value on the market right now. You can click the image below for more details.
Mars Hydro TSW 2000:
It emits a full white light spectrum (including blue & red) . It’s the most modern LED grow light currently on the market, and will cover a 3’x3′ space with ease. You can click the picture below for more details.
Mars Hydro SP-3000:
The Mars Hydro SP-3000 is a great modern white spectrum grow light at a mid-price range cost. You’ll be able to light a 3×5 or in some cases 4×5 foot area with this full white spectrum grow light. You can check out my review of the SP-3000 here.
What Are The Best White LED Grow Lights For Small Plants?
The white spectrum LED grow lights above are meant for fruit, vegetables, or cannabis. They cover a 3×3 foot area, and may be overkill for smaller plants such as flowers or succulents growing in a small 1×1 foot area.
If you’re looking for a small white spectrum LED bulb that’ll cover a 1×1 foot area and is sufficient for smaller plants like succulents, flowers or seedlings, I highly recommend the Sansi 40w daylight LED bulb. I have these bulbs at home and wrote an article about my experience with them here. You can click the image below for more details.
Sansi 40 watt full white spectrum LED bulb:
White, Red and Blue Wavelengths – Not White Alone:
Since most white LED lights run at a lower light absorption rate, and are not comparable to natural sunlight, the use of red, purple, blue or green LED lights are often used in combination with white lights.
When red and white, purple and white, blue and white or green and white LED lights are used in combination, the outcome of light absorption is much better.
Using white LED lights with other primary color LED lights offer the added benefits of visibility and better room atmosphere. This allows plant growth to occur in any room of a home versus a specified plant room.
In some cases, people have used a combination of red, white and blue LED lights to give the plants their much-needed light combinations while enriching the room with a patriotic glow.
When it comes to indoor plant growing, studies have shown the use of LED lights has been found superior to traditional plant growing lights. Using LED lights significantly reduces energy consumption and does not create overheating or the hazards of higher heat risks from ongoing daily usage.
There are debates on the best light that gets the best results for growth. One of the biggest debates is the effect of white LED lights on plant growth.