Effects on Plants
With the increase in human population, so is the increase in the demand for food and vice versa. Since immemorial, man has sought to increase his farm output due to increased demand. And science will inform you that the sun provides the energy in the food chain, and without it, the food chain will not exist. Humans have revered the sun as the ultimate source of this life-giving energy for centuries. Yet, as technology evolves and our understanding of plants deepens, a new era has dawned, illuminating the path to remarkable agricultural feats; the plant lamp revolution.

As an ardent enthusiast of plant cultivation and cutting-edge technological advancements, I am continually enthralled by the convergence of photosynthesis and the mesmerizing realm of photons. The fusion of scientific knowledge and plant growth practices, embodied in the innovation of LED grow lights, has undeniably redefined how we nurture and cultivate our cherished plants. These luminous wonders, as I love to call them, intricately engineered to replicate and manipulate precise light wavelengths, stand as the foundation of a contemporary agricultural transformation.

Have you ever been able to utilize specialized grow lamps for your plants? If you have, then surely you’ve marveled at the remarkable influence that light can exert on developing your botanical companions. Today, I take you on a long yet intellectually fascinating journey to explore the pivotal role played by the spectrum of light in nurturing plant growth and how this intersects harmoniously with the revolutionary technology of LED grow lights.

The Visible Light Spectrum Range

For starters, light is a form of electromagnetic radiation characterized by intensity, frequency, wavelength, and polarization properties. Unlike sound, it can propagate through air or vacuum in the form of waves. The electromagnetic spectrum herein encompasses a wide range of wavelengths, and when discussing light, focusing on wavelength rather than color is more accurate. The visible light spectrum, the portion perceivable by humans, spans a small range between 400 and 700 nanometers (nm), with 1 nm equivalent to 10 ^ 9 meters.

The wavelengths crucial for plant growth are particularly interesting for growers like you. Plants are responsive to wavelengths including ultraviolet radiation (260–380 nm), the visible spectrum (380–740 nm) encompassing photosynthetically active radiation (PAR) from 400 to 700 nm, and far-red radiation (700–850 nm).

Distinguishing between greenhouse and indoor environments is essential when considering the visible light spectrum nm for plant growth. My indoor setups require a grow light spectrum that comprehensively covers the wavelengths necessary for plant development. Conversely, in a greenhouse, the light spectrum received by plants combines artificial grow light and the natural solar spectrum, but that is not today’s bottom line. The proportions of each wavelength band that plants receive profoundly influence their growth. Therefore, optimizing the light spectrum range in terms of its constituent wavelengths is critical for successful cultivation.

Understanding How Plants Respond to Light

Plants exhibit fascinating responses to light, utilizing it for photosynthesis and photomorphogenesis. Light fuels photosynthesis and conveys critical environmental information, guiding a plant’s growth and survival strategies.


Plants leverage light to perform photosynthesis, a vital process of converting light into chemical energy. Moreover, light is an informational cue guiding a plant’s developmental responses. The composition of light, rather than just its intensity, plays a pivotal role in this process. The light spectrum within 300 to 800 nm triggers developmental changes, while UV and infrared light contribute to plant morphogenesis.


Photomorphogenesis is how plants adapt their growth in response to different light spectra. For instance, plants might bend towards a light source due to photomorphogenesis. This process also influences crucial developmental stages like germination and flowering.

The Power of Photoreceptors

Plants interpret light through specialized pigments called photoreceptors. These photoreceptors are finely attuned to distinct wavelengths within the light spectrum. Three major types of photoreceptors orchestrate these responses:

  • Phototropins: In the UV (A) and blue range, phototropin induces plant movement and governs cell chloroplast movement. They’re responsible for phenomena like stems bending toward light and stomata opening.
  • Cryptochromes: Also sensitive to UV (A) and blue light, cryptochromes determine light direction. They regulate processes like stem elongation inhibition, stomatal function, pigment synthesis, and sun-tracking by leaves.
  • Phytochromes: Responsive to red and far-red light, phytochromes play a central role in photomorphogenesis. They exist in two forms, Pfr and Pr, which interact to influence stem elongation, shade avoidance, chlorophyll synthesis, and flowering responses.

Now, armed with an understanding of light spectra and photoreceptors, how can growers apply this knowledge effectively? Crafting an optimal light spectrum for cultivation hinges on comprehending a plant’s response to different light colors.

How Does Each Light Spectrum Affect Plant Growth?

Although outcomes depend on other variables, there are general guidelines you may adhere to when utilizing the light spectrum to induce various plant responses. I’ll dig into how each waveband is used in plant growth so you can trial light spectrum strategies in your growth environment and with your chosen crop varieties.

Violet and Blue Light

Violet and blue light, encompassing wavelengths from 380 to 500 nm, is a vibrant wake-up call for plants. The influence of blue light on plant development and flowering is distinctive and significant. Integrating blue light into cultivation practices can enhance plant quality across various leafy greens and ornamental crops. Seedlings, in particular, thrive under the influence of blue light.

Essential Role of Blue Light

A modest dose of blue light is essential for sustaining average plant growth. To put it in perspective, if red light is akin to a car’s engine, blue light assumes the role of the steering wheel in adjustable spectrum lighting strategies. The intricate interplay of blue light with other wavelength bands fosters several advantageous outcomes for plants:

  •     Plant Compactness and Root Development: Blue light, when combined with other spectra, fosters plant compactness, and robust root growth.
  • Reduced Dependency on Chemical Regulators: I found blue light as a natural growth regulator, potentially reducing the need for chemical plant growth regulators (PGRs). This not only saves you money but promotes environmental sustainability.
  • Chlorophyll Accumulation and Stomatal Opening: Blue light prompts increased chlorophyll buildup and facilitates stomatal opening, enhancing gas exchange and overall plant well-being.
  • Enhancing Secondary Metabolites: Blue light plays a pivotal role in stimulating the production of secondary plant metabolites. For example, it encourages the development of anthocyanins, intensifying color in leaves and flowers. Additionally, it triggers the formation of compounds that enhance flavor, aroma, and taste, as observed in certain cannabis varieties.
  • Environmental Perception: Blue light holds significance as it’s readily absorbed by plant photoreceptors, contributing to the plant’s perception of its surroundings. By adjusting the proportion of blue light, plants can be persuaded that more light is available, leading to shifts in plant behavior.

Remember that higher intensities of blue light can exhibit dual effects on flowering in day length-sensitive crops such as lettuce or potatoes. Blue light doesn’t affect flowering regulation at low light intensities. Therefore, it can be safely employed at night to influence other plant traits.

Furthermore, an increased ratio of blue light contributes to inhibiting cell elongation. This translates to shorter stems and thicker leaves, benefiting specific cultivation goals.

Green Light (500-600 nm)

Greenlight wavelengths often take a backseat in plant growth due to chlorophyll’s lesser absorption affinity than other wavelengths. This is precisely why most plants sport a green hue, as chlorophyll reflects green light while absorbing red and blue. However, recent insights reveal that the underappreciated green waveband has a story to tell, challenging preconceived notions.

Green Light’s Unconventional Role

Greenlight, often underestimated due to its neutral appearance, holds a fascinating role that has been overlooked. Emerging research suggests that green light assists in photosynthesis by penetrating deeper into the plant canopy. This characteristic proves pivotal in scenarios of dense growth, where shading is prominent. Green light drives photosynthesis in shaded or lower leaves, serving as a lifeline for their growth. Unlike red and blue light, approximately 80% of green light passes through chloroplasts, while leaves absorb about 90% of red and blue light, allowing less than 1% to transmit.

Green Light’s Dual Advantage

Consider this scenario: when light availability is abundant, chlorophyll often reaches a saturation point and can no longer effectively absorb red and blue light. Here comes the twist: green light can excite electrons within chlorophyll molecules tucked deep within leaves or lower chloroplasts. This unique trait of green light boosts photosynthetic efficiency, potentially elevating crop yields, especially under bright light conditions.

Signaling Canopy Position and Morphological Changes

Have you ever been caught up in the rain on the road and had to seek shelter in the shop nearby? Well, plants, like humans, respond to the various stimuli in their surroundings, in this case, light. The ratio of green light to red and blue wavelengths delivers a subtle signal to plants about a leaf’s position within the canopy. This signaling prompts morphological shifts aimed at maximizing light absorption.

When shade conditions are indicated, the plant undergoes growth behavior associated with shade avoidance. This might encompass extra growth or elongation of internodes and leaves, along with adjustments in leaf angle to capture incidental light.

Regulating Stomatal Aperture

Greenlight also influences the stomatal aperture, governing the opening and closing of plant pores crucial for gas exchange.

Supplementing Green Light: Indoor vs. Greenhouse

Interestingly, greenhouse setups require less additional green light, as natural sunlight provides a substantial dose. Conversely, indoor environments stand to gain more from supplemental green light, as they lack direct sunlight exposure.

Red Light (600-700 Nm)

For me, the light within the red wavelength range (600-700 nm) is one of the most potent triggers for photosynthesis and amplifying plant biomass growth. Think of it as the accelerator pedal for your plants’ growth engines. With its decisive influence on flowering and fruiting, red light takes center stage as the conductor orchestrating the plant’s reproductive phases. Its role extends beyond growth—it acts as the plant’s cue to initiate the transition from vegetative growth to the much-awaited flowering stage.

Balancing the Equation: The Role of Blue Light

However, embracing red light in isolation can lead to an interesting phenomenon called “red-light syndrome.” This syndrome can impede leaf photosynthesis when blue light is absent. The absence of blue light can also result in undesirable growth profiles, characterized by elongated, tall plants with thin leaves—far from an ideal growth scenario. Yet, there’s a remedy—a judicious infusion of blue light to counterbalance the red light. This strategic pairing encourages the development of compact plants adorned with thicker leaves. The next question would be how? Well, that’s where Grow Lights come in by providing light of correct and balanced wavelength to your plant.

Yet, exclusive reliance on red light could mean that plants fail to harness the full spectrum of available light energy, leading to inefficiency. While red light is indisputably pivotal for plant growth and developmental processes, it thrives in harmony with a balanced light spectrum.

Far-Red Light(700 – 850 Nm)

Far-red light occupies the tail end of the red spectrum, spanning from 700 to 850 nm. This portion of the light is referred to as super-visual, as most of this waveband is outside the visible portion of the spectrum.

  • Shade Avoidance: A noteworthy outcome of far-red light exposure is activating a shade avoidance response. This intricate process prompts plants to undergo elongation and stretching. This growth strategy is a mechanism that plants employ to adapt to light-deprived conditions, maximizing their light-capturing potential. The phenomenon also introduces a novel perspective on how plants interact with their environment.
  • Illuminating Flowering and Leaf Expansion: Far-red light doesn’t merely trigger elongation. It also plays a very pivotal role in promoting flowering among long-day plants. Additionally, it fosters the expansion of leaves, enhancing the surface area available for photosynthesis. The intricate interplay between far-red light and these critical processes underscores the complexity of plant responses to their light environment.
  • Photosynthetic BoostRecent studies have unveiled an intriguing facet of far-red light—its ability to enhance the efficiency of the photosynthetically active radiation (PAR) waveband. While traditionally not considered a core contributor to photosynthesis, far-red light now emerges as a potential enhancer of the vital process. This revelation sparks interest in exploring new dimensions of plant physiology and growth optimization.

Harnessing Far-Red’s Potential Wisely

Achieving a harmonious equilibrium is pivotal when incorporating far-red light into plant growth strategies. Excessive exposure can lead to unintended outcomes. Plants subjected to high levels of far-red light exhibit elongated, weakened growth and reduced chlorophyll content that manifests as yellowing leaves. This aesthetic shift carries implications for the marketability of cultivated plants.

Far Red Light and LED Grow Lights

Emerging as a beacon of innovation, LED grow lights offer a means to harness the potential of far-red light. Intelligently manipulating light spectra through these advanced lighting technologies enables precise modulation of far-red exposure. This control method empowers us to unlock the benefits of far-red light with precision, ushering in a new era of optimized plant growth strategies.

Ultraviolet light (300 – 400 nm)

At the epilogue of the spectra is the UV radiation, which encompasses wavelengths between 100 and 400 nm. UV direction shares similarities in its impact on both human health and plants. Just as prolonged exposure to UV light can cause sunburn to us, plants can also suffer damage from excessive UV radiation. However, plants possess mechanisms to counteract the adverse effects, like our bodies developing a tan from short sun exposure.

Plants, similar to human bodies, respond to UV radiation by producing protective compounds that help alleviate potential tissue damage. This response often manifests in changes such as the darkening of plant pigments or increased purple hues. Recently conducted research in 2022 suggests that UVB light exposure can lead to higher concentrations of essential oils and phenolic compounds in certain herb species.

The lousy marketing of UV radiation aside, the potential benefits of UV light exposure for plants include heightened leaf coloration, increased leaf thickness, and improved resistance to various stressors like environmental challenges, pests, and fungal infections. However, it’s important to note that excessive UV light can hinder photosynthesis.

Harnessing All the Light Spectra With LED 

The interaction between various light colors can result in greater photosynthesis than expected from their individual effects. Notably, a study involving lettuce demonstrated that introducing 24% green light to a red-blue LED setup led to enhanced plant growth and biomass. It’s worth mentioning that the light intensity (PAR levels) was kept constant at 150 μmol/m2/s for both conditions.

This emphasizes the significance of recognizing the intricate interplay between different light wavelengths. Instead of depending solely on a single light wavelength, considering the combined effects of diverse wavebands becomes crucial for promoting robust plant development. Once again, LED would play a perfect role in balancing this interplay.

The Cannabis – LED Connection 

Cannabis cultivation has become a hotbed of research in LED grow lights. Studies have revealed intriguing correlations between light spectra and cannabinoid production. Manipulating the light spectrum during different growth stages has been shown to affect the yield and potency of cannabis.

Specifically, LED grow lights with a higher proportion of red wavelengths encourage prolific flowering, enhanced resin production (critical for cannabis), and increased yield potential. Tailoring light to trigger specific responses in cannabis plants underscores the potential for even more significant advancements in indoor cultivation practices.

Using LED Grow Lights to Provide the Right Light Spectrum and Intensity

Plant lamps provide plants with the right light spectrum and intensity. They are more efficient than the traditional grow lights, emitting a more comprehensive range of wavelengths that benefit plant growth.

When navigating the selection of an LED grow light, I will advise you to take into account several key considerations:

  • Wavelength Spectrum: The chosen LED light must cover a broad spectrum of wavelengths, encompassing essential colors like red, blue, and green. This comprehensive spectrum ensures that your plants receive the necessary light components for various stages of growth.
  • Light Intensity: The adjustability of light intensity is a crucial feature to seek in an LED grow light. This attribute empowers growers to fine-tune the illumination level, enabling precise tailoring of light exposure to meet the specific requirements of different plants.
  • Light Fixture Size: The LED grow light fixture’s dimensions should align with the growing area’s dimensions. This compatibility ensures uniform coverage and prevents under- or overexposure of plants to light. Matching the light size to the cultivation space is pivotal for optimal results.

Incorporating these factors when selecting an LED grow light elevates the potential for successful plant cultivation, as it provides a balanced and customized light environment.

Bottom Line

Like that mandate, the plant-growing field has to embrace tech for the future in tech. LED lighting technology is improving, allowing us to change the light wavelength plants get. We can choose a specific spectrum of visible light to make plants grow in certain ways. Understanding how plants react to different light wavelengths and using this knowledge enables plants to grow in the way that we want. It’s like giving them instructions using light and technology. Happy planting!


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