Why I still believe in Red/Blue LED Grow Lights

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Top 3 Reasons to Consider RED/BLUE LED Grow Lights

By Chris Higgins

LED grow lights have been a very hot topic for more than a decade now and as with any (relatively) new technology, the first decade of LED grow lights has seen massive changes and improvements.  From the amount of companies selling LED grow lights to the technology powering what they are selling, we have all heard or read why each company feels their technology is the best. In recent months, that conversation has included topics ranging from fixture design to cooling to efficiency (umol/j) to intensity (umol/m2/s) to color spectrum (nm) (all of which are directly related when it comes to fixture performance).  I dare say we have probably heard and seen everything that we are going to see.

When the sun is out and the LEDs are on the plants get exposure to full spectrum.  Remember, electric light in the greenhouse is supplemental only.

So why am I writing this article?

I am writing this article because the majority of commercial growers are still invested in older technology.  I know many of these growers are interested in innovation, but definitely don’t want to invest until they feel the technology is proven.

I also know that this article is bound to have many people and companies disagreeing with me.

That is why I am going to approach this from the perspective of what we need to happen, versus what the technology might be capable of doing.

First, I am a believer in red:blue led grow light concept.  And here are the reasons why:

1.  THE GREENHOUSE

I am still a believer in the commercial greenhouse and I am still a believer in the sun.  Most commercial greenhouse growers who are investing in light are only investing in supplemental light.  This means that for much of the year they are not using their grow lights or they are only using them for a short period of the day.  They are instead relying on the sun to provide most of the energy for the plants. This also means that the plants are getting full-spectrum light from the sun (or at least what spectrum is able to pass through the glazing) and even when the grower is using their grow lights the sun is normally contributing a significant amount to the percentage of DLI (Daily Light Integral) the plants receive each month.  Based on the knowledge we (as an industry) have today plus the equipment we have commercial access to, a well designed greenhouse with supplemental electric light is a proven and economic tool for year round plant production in a wide variety of climates and geographies.

Image shows what greenhouse light looks like when there is natural sunlight and high blue/red LEDs on at the same time.

This is not to say that I don’t believe in vertical farming.  It’s just to say that the greenhouse has been around long enough to be proven to work in a wide variety of conditions.  In a follow up article I will discuss how important vertical farming is to the future of different parts of the agricultural process.   

2. EFFICIENCY and INTENSITY

My research continues to prove that the most efficient LED grow lights are red and blue.  It also shows that those light fixtures with highest output (umols/s) are red/blue led grow lights.  Depending on the ratio of red:blue this could mean as much as a 45% savings in electricity for greenhouse lighting depending on what fixtures and type of technology one is comparing.  This could also mean about 10% more light per fixture, which means less overall fixtures in the farm. For those growing food crops or ornamental crops, these types of savings can have a big impact depending on where the farm is located and how much the farm is paying for electricity.  Efficiency should also be front and center for those growers interested in winning the sustainability discussion. There are plenty of people opposed to controlled environment agriculture. Their main opposition is the energy footprint. And that is a fair argument. That’s why it’s important that we learn to maximize production based on using the most efficient tools.

3. OPERATING COST

If we want to be profitable farmers, now and well into the future, we need to constantly focus on operating cost.  This means counting pennies and making the best investment in technology we can based on what we know and what we have access to.  Energy efficient equipment often costs more, but if you maximize the operational savings and take advantage of utility rebates, the right equipment/investments will start paying you back in a short period of time.  And since red/blue leds are proving to be the most efficient option, it only seems to make sense that we figure out how to adapt our production strategies in order to use this technology.

Again, it’s very important to remember that the only use of supplemental lighting is to increase plant performance. Plants absorb different light colors (light spectrum) at different levels. Science supports the fact that the colors most absorbed by plants in order to promote photosynthesis are red and blue. Meaning the rest of light colors will require a higher light intensity in order to trigger the same photosynthesis levels reached by red and blue LEDs. Photosynthesis is the main process in plants leading growth and development. By using red and blue light you can be sure the money you invest in your light is better used.

So, why would one not invest in red/blue leds?  Is it because the greenhouse crop does not grow well under the lights?  Not based on my experience. Many of my customers, staff and friends have been growing under red/blue leds for years now.  The crops look great and the yields are comparable when light intensities are equal. The best argument I have heard has nothing to do with the crop.  It’s that “employees” don’t like it and might be uncomfortable. That is a fair argument. But, in my opinion that is an argument with a very easy work around. Growers should look at strategically placed work lights that are capable of producing bright white light at a lesser cost.  These lights will be less efficient, but not need to run as long as the grow lights (because they only need to run when workers are present) and because of that these less effective fixtures will not have a negative impact on the potential efficiency and op ex savings.

In greenhouse horticulture there is a golden rule:
1 percent more light ensures 1 percent more yield.

Important definitions:
Supplemental light:  A strategy used in commercial greenhouse production to increase crop production during time periods with low levels of solar radiation by adding photons from electronic light fixtures.
Daily light integral: Describes the number of photosynthetically active photons that are delivered to a specific area over a 24-hour period. This variable is particularly useful to describe the light environment of plants. 
Lighting efficiency:  The appropriate metric for plant lighting is photosynthetic photon efficacy (PPE). This is the PAR photon output (unit of micromoles per second, or μmol·s–¹) divided by the input power (watts, or W) to produce that light. Thus, the unit becomes μmol·s–¹·W–¹, and because one watt (W) equals one joule per second (J·s–¹), the ratio can be simplified to μmol·J–¹ (μmol per second/joule per second).

Important questions for further discussion, please email me or message me for further discussion:

  1. Why does the location of the farm matter?  
  2. Why does the cost of electricity matter?
  3. Do renewables make this argument stronger?  
  4. And why is renewable energy so important for sustainable agriculture moving forward.

Additionally, for more information on LED grow lights or to get  a return on investment (ROI) calculation based on your current investment, please email or contact me directly. 

25 thoughts on “Why I still believe in Red/Blue LED Grow Lights

  1. I would like to understand more about all aspects to ensure “financial sustainability” of vertical farming

  2. Wrong, blurple lights are extremely inefficient, hot, loud, and lack required wavelengths, terrible choice for a greenhouse. Light emitting plasma is the best choice for greenhouses.

    1. Hi Derick, Everyone is entitled to their own opinion, and we respect yours. However, the scientific data is out there to support this article. We invite you to continue your studies and hope that we can be a reliable source for you as you do so. Thanks, and we hope you have a great day!

  3. I totally concur. I use a mixture of both. Seems to have better results on average.
    You a classy guy. I like the way you respond even if they are critical to your opinion.

  4. Every lighting scene or recipe is crop specific. Greenhouse, closed containment and or vertical systems all require considerations of micro climatization integration for best result crop yield, energy efficiency and efficacy, sustainability and plant morphology. Determining ‘the best’ lights or lighting conditions also include many other aspects. Static lighting is often a key in creating a dynamic recipe. After all we consider ‘white light’ because we perceive it through our perception as human beings. Each crop plant type has its own physiology, the environmental considerations are varied based on seasonality and result based oriented goals of the operator.

    This is a good post, Chris.

  5. If we seek to debunk Blurple lighting we must ask first what do the light spectrums do for us. green and yellow light do add an extra cost to lighting as they use diodes on the LED board but as significant research shows they provide a much better penetration into the canopy as compared to the red and blue light spectrum. This means less intercanopy lighting needed with the same wattage used when using the green spectrum specifically. This means less money spent on lighting in general if you did require it with Blurple you would likely require less with a full spectrum light. Plus on a side node Blurple lights were designed when diodes were in their infancy and have been stockpiled in China ever since, newer diodes such as the Samsung work more efficiently reducing costs and heat in the grow, as the less efficient a light is the more energy that is not used as light and is wasted as heat.

    1. Hi, thanks for your comment. Our response is written with the greenhouse in mind and LED light being used as a supplemental light source where red and blue LEDs have been proven effective by independent researchers.

  6. Is there a chance that the other frequencies contribute to as yet unknown plant physiological pathways? I recall the idea at one time,, that NPK was all that plants needed to grow, ignoring trace minerals, and microbial life in the soil. Might this be similarly narrow focused? Also, can plants be too optimized, much like feedlot cattle, they are fed an ‘ideal’ diet for weight gain, but the marbled meat is Metabolic Syndrome made visible, and the excess branched chain AAs also contribute to chronic human disease. How might the plants be lacking in defensive Terpenoids or other defensive metabolites that our cells respond to beyond even flavor as in the CTRA gene’s and cellular growth vs repair promotion? I’m not being contrary, just a couple long term 30,000 ft view questions.

    1. Is there a chance? Yes. In fact we know plants respond to a wide variety of wavelengths within the spectrum. But, please remember that this article is written based on LEDs being used in a greenhouse where the plants are receiving a wide spectrum of light produced by the sun. The main limitations to light will be geography and choice of glazing for the greenhouse. LED grow lights in the greenhouse are supplemental to the sun. The sun is still providing much/most of the energy plants require to grow. Most importantly, sunlight itself is not constant. The quality of light you receive looks very different depending on time of day and atmospheric conditions.

      Also remember that this article is not specific to any one variety of crop, that all crops are going to have different requirements when it comes to light and more importantly all light is not good light.

  7. Hi I have a 10,000 lumen volt king shop light with 4 Florence bulbs can I use this to start my seeds indoors in the spring

  8. Hi, great info on this post…however I am not a greenhouse grower..just my tiny house…QUESTION is how do you feel about the blurple lights for indoor growing of succulents and cacti succulents? Do u have any tips or knowledge on timing and height distance? Thanks..

    1. The “burple” lights will do fine inside for succulents assuming you have the right light intensities and a color combination that is about 90% red and 10% blue. (Does not need to be exact.)

      The big question is do you like the “burple” color? If you do, give it a try.

      Its hard for us to tell you what distances to mount the lights because that is based on intensity of the lights which is based on wattage.
      We think you would be safe with 60-90 watts of LED lighting mounted about 20-24 inches from your plants. Photoperiod will be safe at about 14-16 hours per day. (Assuming they are getting zero sunlight.)

      Good luck growing!

  9. 90+ essential vitamins, minerals, etc. that could be available in plants, all have uptake & production responses to specific colors of light, including the middle of the full-spectrum. I have a tunable full-spectrum lamp that delivers Non-Thermal Left-Handed Circularly Polarized Light, which is less expensive, longer life, water proof, & even far more energy efficient than LEDs. Contact me.

  10. I agree the deep red (≈660nm) and deep blue (≈450nm) have the highest efficacy in PAR output.
    The problem is there is no economical supply of LEDs in these bandwidths, especially deep red.
    There are no viable mid power LEDs, only high power which generate too much heat for efficient and low cost convective heat transfer.
    The market demand for white LED strips far exceeds the demand for red and blue.
    I find the white strips of mid power white LEDs with a low CCT (90) have plenty of red bandwidth and are very low cost per photon. Because the white LEDs are phosphor converted deep blue, the same number of photons are emitted for all color temperatures in a given series of white strips. Many believe that the cooler color temperature white lights are better than 2700K. I have grown tomato plants under 2700K and 5700K and the difference in growth was astounding. I also found they grew better under 2700K than sunlight.
    The bottom line is there is no commercial high volume production of red/blue strips.
    The white strips work very well and are economically feasible for grow lighting.

    1. Dear Ybor Farms:

      We tried to learn more about you and your farm by visiting the website you have listed, but it’s not showing as valid? Is there a typo?
      We would like to better understand your comments.

      Are you referring to the diodes themselves? If so, companies like OSRAM offer products like the OSLON Square Hyder Red (4th gen.) Very reliable and highly efficient.
      Cree, Samsung and others also make great products specified for commercial horticulture needs.
      We do understand that there are significant delays in the supply channel, but these companies do make quality products?

      Or when you say strips, do you mean a fixture?

      With a little more detail, we might be able to provide a better response.

      Regarding your trials of different lighting options, do you grow in a greenhouse? Or indoors?

      Thanks for the comments.

      -UAN

      1. I would love to use OSRAM and Cree deep red and blue LEDs. Most µmol per Joule. But the white strips made by Samsung and Bridgelux are very efficient too. Some have a spectrum very similar to R/B and require no heat sink.
        yborfarms is a new venture that will grow edible compact vegetables for containers indoors under LEDs. The website is under construction.
        Most will range in size from 8″ to 24″ when fully mature. Lots of tomatoes and peppers. Cucumber, herbs, peas, broccoli. All will grow well on a balcony or patio. Gardeners can buy plugs or transplants to plant in their own garden.
        I will be using industry standard 1020 trays to grow plugs (128 per tray) and transplant them to 3.5″ sq pots. Then into the final (3-5 gallon) customer decorative planter. I will also sell them as plugs or transplants (3.5″ pot).
        I am using inexpensive 5 tier wire shelving with the LED strips attached to the bottom of each shelf. Each shelf has it own driver with adjustable current. I created an app that finds the ideal height and placement of the strips.
        I am using Bridgelux EB Series strips powered with Mean Well drivers.
        I was a consultant to the University of Florida Horticulture Dept building custom LED fixtures for their grow light research.
        I have been researching LED grow lighting, heat transfer, and plant physiology for over five years. My background is biomedical and electrical engineering.
        I use white strips because blue and red LEDs are too expensive and run too hot. By using mid power LEDs the heat has much better distribution.

        I do have a great design for red and blue strips and have built a bunch using Oslon SSL 150° and Cree with very efficient natural convection heat sinks. Just too expensive to manufacture when compared to using white strips. I pay about 9¢ per kW. The little electricity I would save with the Red and Blue would not pay for the extra expense for the initial cost of the assembled strip and heat sink.

        When at the University of Florida I reported directly to Dr. Thomas A Colquhoun and Dr. Kevin Folta two of the authors of this research paper on light recipes for Sweet Basil. I also worked on some projects with Michael Schwieterman.
        The light spectrum affects the secondary metabolites (e.g. phenylpropanoids phenylpropanoids, monoterpenoids) produced by the plant. These are responsible for the scent and flavor. See Figures 3 and 4.
        Figure 2 shows how well the various light recipes did with respect to plant size and color.
        In my opinion BRY is the stand out recipe. Better than GH and RB.
        The BRG looks pretty good also. Showing the yellow and green are not a waste photons.

        https://www.frontiersin.org/articles/10.3389/fpls.2016.01328/full

        1. Thank you for the detailed response. Our owner knows Kevin very well.
          We also remember that paper. Thanks for helping us connect the dots and best of luck with Ybor Farms.
          We are going to take some time and think about your response.

          1. After taking some time to consider your points, we agree….kinda. Technically you are very correct, we do not want to argue those points.”

            We just think you might have stopped short of what would be needed for most commercial farms/greenhouses. The requirement of a heatsink will depend on how hard you drive the diode. The need for a more robust “fixture” will depend on how much light you need to create, where you need to hang the light and what environment you are placing the lights in.

            Choosing to build a fixture will help you gain in reliability (defined as performance over time.) Please consider that a slightly less efficient fixture that is built to last, might actually be more efficient over time. You might be able to tell that as a company Urban Ag News also wants to keep the “environment” in mind as we think about business decisions.
            We feel a big part of this is buying equipment that will be kept in use for a longer time. We think that a well designed fixture capable of withstanding the highly variable conditions in many production environments will lead to less replacements and less waste generated. That is important to us.

            BTW, we sent an email to Kevin. Hoping to get some feedback from him in the New Year.

  11. The weak point of my design is not reliability, it’s the simplicity and the cheap look. Exposed wires (no exposed copper) and exposed LEDs with no polycarbonate cover. A polycarbonate cover reduces the irradiance significantly. But when the performance of $100 in parts exceeds that of a $1,000 fixture, I’ll accept the cheap look.
    The performance over time is great. I use Mean Well HLG drivers with 62,000 hour (7 year) lifetime with a 7 year warranty. The Samsung and Bridgelux strips are as (or more) reliable that any other LED. Being mid-range LEDs they will last longer than high power red and blue LEDs. Heat reduces semiconductor longevity significantly. The strips I use when run at 1400 mA, ≈40V, 56 watts, with 224 LEDs, the strip temperature is about 42° C. Given the life of a semiconductor is cut in half for every 10° C rise in temperature and how hot the red and blue LEDs run. The longevity of the strips I use will surpass any high power red or blue LED. The strips can easily be used to grow young tomato and peppers at under 30 wall watts.

    I have a photo of young tomato plants from a few years ago when I was experimenting with combinations of height of the LED strip and wall watts. This photo has 4 combinations. Single strip height (from ground) at 12″ and 24″, 8 and 16 wall watts. The “grow chamber” are very cheap. Much cheaper than the wire shelving unit I currently use. But they were very flexible and changing strip heights was very quick and easy. I use 3M Dual Lock Reclosable Fastener tape (velcro like) to fasten the strips.
    https://www.yborfarms.com/growLightExperiment.jpg

    My strips are easily replaced in the field. They are mounted to three 24″ strips of aluminum per 14″ x 30″ shelf tier.
    I use three standard 1020 trays with the 10″ tray width across the 30″ shelf with the 20″ tray length with 3″ of the tray hanging over each end to the 14″ shelf.

    When using strips the grow area is reduced by 12″ (2×6″) on each end of a strip of LEDs.
    I previously used a 27″ x 17″ germination tray. I have an app that creates a heat map of the uniformity for a fixture of strips. This is an image from the app for the 27″ x 17″ germination tray. The strips are 44″ long with LEDs right up to the very edge of the strip. The first line at the top is the width inches of a 24″ x 48″ grow chamber. So there are 2″ between the end of the strip and the edge of the grow chamber. Notice how the area from 10″ to 36″ across has near perfect uniformity. But that’s only because the 44″ strip extends over 8″ beyond the tray on both ends (44-27) = 17″ and 17″÷2 = 8.5″ each end). When you buy a rigid fixture for each grow area (e.g. a single shelf) the is a lot of waste.
    Let’s compare a 24″ x 36″ grow area (e.g. a grow tent). You buy a 24″ x 36″ fixture and you get good uniformity for only a 24″ x 24″ area if the fixture is 36″ long.

    With my design I have 44″ strips on a 36″ shelf. Ugly with the ends of the strips sticking out? Yes, but if you put the shelving unit side by side and get the ends of the strip to butt up against each other you just increased your grow area by 12″. This works very well with large industrial shelving. But I’m cheap. $60 vs. $300 per self. And I lose 6″ for the
    I could explain the uniformity app but that would have to be full article. The app was verified with a StellarNet Blue Wave spectrometer.
    https://www.stellarnet.us/spectrometers/blue-wave-miniature-spectrometers/
    I measured various points on the floor of the grow area, compared them to the app, and the accuracy was within a couple of percent.
    Testing the app was not easy. First off there was no way to verify my equations online. So I made an app for that where I compared my equations, for each wavelength, with the measurements of the Blue Wave spectrometer. http://www.growlightresearch.com/ppfd/convert.html
    I have many apps. This one compares individual LED’s radiant distribution: http://www.growlightresearch.com/ppfd/dangles.php#
    I have build strips with many of these LEDs.

    And this photo may give you a better idea of what I am doing. http://www.yborfarms.com/MarketExhibit.JPG
    The tray of seedling was one of the first I had grown and got a bit raggedy being hauled back and forth to the farmers market.
    I was doing market research at the farmers market.

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