How Dynamic LED Grow Lighting Is Transforming Horticulture

In the rapidly evolving landscape of floriculture and controlled environment agriculture (CEA), dynamically tunable LED lighting is emerging as one of the leading technological innovations. These advanced lighting systems enable precise, real-time adjustment of the light spectrum and intensity in response to the plants’ needs, natural light levels, and even, in some instances, demand on the electrical grid. While the potential benefits of this new lighting technology cannot be denied, there are also some potential drawbacks and/or challenges that should be considered. This article delves into both the pros and cons of multi-channel tunable LED lighting to help you decide whether it makes sense for you to implement it in your commercial growing operation.​

Customizable Light Recipes

Tunable LEDs enable precise control over the light spectrum, allowing growers to tailor lighting conditions to the specific requirements of various plant species and developmental stages. So, with dynamically tunable light fixtures, on-demand spectral customization can be used to enhance photosynthesis, improve plant morphology, and potentially increase yields.

This “tunable” feature of dynamically tunable LEDs could be great for growers in highly competitive and/or specialty crop markets where the ability to dial into the optimal spectral recipe for a specific cultivar can result in crop quality and/or productivity improvements that distinguish them from the competition.

In other cases, growers may wish to “futureproof” their grow environment to allow for different crop types they may choose to grow in the future — based on the shifting profitability of certain crops or other unforeseen impacts, such as crop virus outbreaks.

Although growers typically think of a (4-channel) fixture that can deliver a fully-tunable spectrum when they hear “dynamic spectrum”, it should be noted that there are also 2- or 3-channel LED products available that offer growers a broad, efficient spectrum on the main channel that can be used for the majority of the lighting schedule, but with one or two additional channels that allow for limited applications of other wavelengths as and when they are needed.

For example, the ParFX Ultra 2-Channel fixture has a recipe of 90% Red : 5% White : 5% Blue on the main channel with a second Far-Red channel. Studies have shown that specific applications of Far-Red light can be very beneficial. For a chrysanthemum grower for instance, having the ability to apply a dose of far-red light as and when needed could be great since studies have shown that stem elongation in chrysanthemums can be controlled by applying low-intensity far-red light for half an hour at the end of the day to deliver longer flowering shoots (Wageningen University & Research, 2023). Similarly, far-red light has been shown to produce larger leaves for cucumbers and peppers — minimizing fruit stacking or, in the case of strawberries — creating a more open canopy that allows for more light to reach the fruit and easier harvesting.

Conversely, the application of blue light* can be used as a growth regulator to suppress growth extension, which can be advantageous when height requirements are a factor or when plants need to be more compact in size. Blue light receptors may also play a role in the production of carotenoid and anthocyanin development. This can be seen in leaf coloration, such as enhancing the color of red lettuce varieties or increased pigment and nutrition in peppers (Naznin et al., 2019).

Determining the optimal light spectrum for each crop and growth stage, however, requires extensive knowledge and experimentation. The interactions between light spectra and plant responses can be complex, and missteps could lead to sub-optimal growth and/or decreases in yield.

So, although the idea of being able to adjust and “experiment” with your grow lighting is undeniably exciting and can serve as a valuable tool for some, the reality is that for commercial growers, consistency and predictability are key. For growers subject to supply contracts with grocery chains/garden centers, their main focus is going to be on ensuring consistent quality and yield in order to deliver on those contracts. In this case, they would likely prefer to eliminate as many variables as possible. Since changes in light intensity and spectrum can affect not only other inputs like nutrient uptake and VPD but also the plant morphology, growers are advised to initially set up a trial area to see how their crops perform under various spectral recipes to avoid potentially compromising one or more harvest cycles across their entire crop.

For those growers who don’t want to spend time trying to figure out the optimal light spectrum (and necessary adjustments to other inputs) for each specific crop and/or cultivar — a fixed spectrum (optimized to accommodate multiple crop types and growth stages) might make more sense.

Maintaining Optimal Light Intensity

For years growers have used the “1% light intensity rule”, which states that a 1% increase (or decrease) in light intensity results in a corresponding 1% increase (or decrease) in yields — up to a saturation point (Marcelis et al. 2006).

Many researchers, including Dr. Erik Runkle and Dr. Bruce Bugbee, also agree that in CEA applications where high light intensities are required, the light quantity (intensity) generally has a stronger and more consistent impact on crop yield than light quality (spectrum).

So, although growers are aware of the relationship between light intensity and yield, they may not realize that, when it comes to dynamically tunable LED lighting, the amount of light (PPF) produced by any tunable light fixture will fluctuate based on the spectral recipe dialed into.

Therefore, spectral tuning needs to be carefully balanced with the maintenance of adequate light intensity. As a grower, you need to weigh the economic benefits of the potential morphological enhancements (taste, color, nutritional value, etc.) for your crop vs. the potential decrease in yield.

For additional information on dynamic LED grow lighting, including energy efficiency and cost benefits, please read the original article found on the P.L. Light Systems website.

 

*It should be noted that due to the high energy of the wavelengths, working under high-intensity (especially blue) light in greenhouses or indoor grows may pose a risk to eye health.