How LED Spectral Tuning Technology Gives Cultivators More Control

When it comes to experimenting with the light spectrum, LEDs have become a critical tool for innovators.

A shifting climate, energy concerns, and space restraints have all pressured horticulturalists to find new ways to efficiently grow their crops. By tapping into the ingrained abilities plants possess to physically respond to different light qualities, cultivators have much more control over the outcome of their harvest than they did only five years ago. They now have the option to elicit faster growth with fewer square feet, all without sacrificing quality. Much of this progress – and the exciting possibilities ahead – is credited to spectral tuning.

Spectral tuning is one of the most talked about advancements in LED capabilities. Growers get the most out of spectral tuning by understanding the complexities behind plant receptivity to light and the contexts in which spectral tuning can become a major game changer.

How Plants “See” Without a Central Nervous System

For eons, plants have been evolving to respond to seasonal changes. We are familiar with it too: the awakening of spring, the long and balmy days of summer, the burst of colors associated with autumn, and the quiet hibernation of winter. We adapt to these changes with our outerwear and behavior. Of course, what we wear in the summer – bathing suits and T-shirts – isn’t appropriate for the winter’s chill, which calls for thick knits and long underwear.

Plants, specifically, have developed a complex awareness of even the subtlest adjustments in their environment’s spectral light quality. They, too, realize that not every day reflects the same intensity as the summer solstice, June 21. While they don’t “see” light the same way that humans do, plants recognize the changing quality of light and react in certain ways to not only effectively photosynthesize, but also to improve their chance of survival and reproduction.

Photomorphogenesis 101

Photomorphogenesis describes a plant’s physical responses to different light qualities and quantities.

One trigger for photomorphogenesis is spectrum. The light spectrum indicates the wavelength of light being delivered. Wavelengths are measured in tiny nanometers; visible light falls between 380 and 740nm, which is only a very small segment of the total light spectrum.

The spectral light delivered by the sun is perpetually changing throughout the day, the month, and the year. Biologically, different wavelengths of light speak directly to hormone receptors found within plants: Chlorophyll A and B. These receptors trigger different physical behaviors in the plant. Photomorphogenesis might be expressed by the expansion of a root network, germination, or prolonged vegetation.

Generally speaking, spectral light that is warmer, appearing redder to the human eye and with wavelengths between 600 and 700nm, elicits flowering. On the other hand, cooler light – anywhere between 400 to 500nm – encourages vegetation, supporting stem, leaf, and root development.

Utilizing a combination of spectral light is key: keeping plants under only red light can result in too much elongation whereas only blue light may inhibit flowering. However, this varies from species to species and some nuance is required for finding the best spectral combinations for individual crops.

For cultivators, photomorphogenesis is one of the most important aspects of plant biology to understand – especially as demand grows and available space is increasingly limited.

Harnessing Spectral Tuning’s Full Potential

With spectral tuning capabilities in LED light technology, growers can replicate the natural transition of the seasons and therefore influence the photomorphology in their crop. Different combinations of spectral light can result in various physical appearances; some of the impressively vibrant coloring found across cannabis strains may be attributed to experimenting with the possibilities of spectral tuning.

This capacity has revolutionized indoor horticulture as cultivators are able to adjust the eventual outcome while also supplying the best spectral light for each stage of growth. There are several practical applications for spectral tuning within cannabis. A few to highlight include:

• Supporting Seedlings – The seedling stage is when a plant is at its most vulnerable. Providing the appropriate light spectrum can help with root establishment and the development of sturdy stems.

• Prolonging Vegetation – Some may want to encourage vegetation, especially to prevent stretching. Spectral tuning allows cultivators to nurture big, leafy plants, while also holding off on flowering.

• Accelerate Flowering – Cultivators, especially those facing a high consumer demand, may want to have larger harvests with a shorter grow time. Specific spectral combinations trigger flowering. At this point, cannabis cultivators can isolate
female plants to prevent the development
of seeds.

• Condensing the Crop – As the demand for vertical farming increases, shorter plants are necessary. With the right combination of spectral light, branch nodes will be closer together, keeping the plant wider rather than taller, while still healthy.

The Promise of Spectrally Tunable LED Lights

The endless possibilities offered by spectrally tunable LED lights truly capture the imagination: what can be accomplished through spectral tuning in the future? With continued development, will our focus shift away from outdoor agriculture with its variable weather, pests, and pollution? Someday, will LED-supported indoor grow facilities become as ubiquitous as corn fields along the highway?

Cultivators who embrace spectral tuning are able to influence each stage of a plant’s growth, whether tending to cannabis or tomatoes. Spectral tuning opens up the potential for indoor horticulture to replace more conventional, resource-intensive modes of agriculture. With its appropriate application, it may bring year-round produce to places where vegetables are usually hard to find.

Even NASA recognizes the potential for spectral tuning. Researchers have explored what spectral combinations delivered by LED lights best suit growing operations aboard spacecrafts or even on a distant planet like Mars. Spectral tuning presents a way to keep plants alive even in a harsh, outer space environment.

As established, the light spectrum plays an indispensable role in plant health. The culmination of millions of years of evolution is plants’ powerful ability to physically respond to light – even that which is invisible to the human eye – through photomorphogenesis. Today, growers have the technology to use this natural phenomenon to their benefit.

Experienced and rookie indoor cultivators alike can benefit from incorporating spectral tuning into their grow’s lighting systems. A good place to start is researching which tunable LED lights are currently available on the market. Many industry experts are willing to offer support, insight, and help with installing and utilizing spectral tuning. Furthermore, as LEDs have become more widespread in the indoor agriculture community, they have also become more affordable – advanced technology is more accessible and easier to use than ever. With spectral tuning, growers can execute complete control over their crop and reap the benefits at harvest.

Image by Daniel Reche from Pixabay 


  • Andrew Myers is President of ProGrowTech. The company helps commercial horticulture operations increase profitability, yield and energy efficiency with industry-leading LED lighting systems. For more information, visit

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