How Does the Color of Light Affect Plant Growth?

The moment someone sees the multi-color rainbow emitting light in the sky, it makes everyone cheers and points. Does it excite you, too? Well. It’s Obvious!

This process is better explained by Science as a refraction effect of sunlight on moisture. But if we say these lights are fundamental to plant growth and development, Would You believe it?

Yes! Research forces us to. Horticulturists now understand that these varying intricacies of light within the spectrum substantially contribute to plant sustenance and growth.

If you’re unaware of “How Do These Colors of Light Affect Plant Growth,” you must read this blog until the end.

Delve with us in knowing how different colors of light intricately shape the destiny of plants, steering them from the first tender sprout to conquering bloom.

I. Introduction

Importance Of Light In Plant Growth

Light is something we all take for granted unless there comes a need to grow something in the Arctic Circle.  More specifically, when doing indoor hydroponics, you start to appreciate how valuable light truly is.

It’s no wonder that plants are incredibly conditioned to their light environment. They grow towards it, compete for it, and simply can't live without it.

In the horticulture realm, light serves as both a source of energy and a guiding force shaping every stage of a plant's life.

At the core,  light is the primary conductor in facilitating the process of photosynthesis–harnessing the sunlight energy to convert carbon dioxide and water into sugar –and driving the course of their growth and development.

It’s nothing short of miraculous, fuelling and nurturing our green companions toward vitality and abundance. The quality, intensity, and duration of light are significant factors that put together this botanical harmony, influencing everything from leaf size and root development to flower production.

Overview Of The Impact of Different Light Colors

The light spectrum is spread into varied color wavelengths, ranging from ultraviolet to infrared rays; and each color has its role in developing and aiding the captivating elements of life.

The intense concentration of blue light, for instance, is a catalyst for lush, vegetative growth, encouraging sprouting and the development of strong roots. It is the radiant force that influences processes like leaf expansion, chlorophyll production, and expanding plants towards a bushier, more vibrant form.

On the other hand, red light, ranging from 600-700nm wavelength, is an important color light for promoting budding, flowering, and biomass growth. Red, when combined with blue light, is highly effective in regulating photosynthesis, contributing to desirable growth characteristics.

Therefore, plants grown indoors with 80 to 90 percent red light and 10 to 20 percent blue light are quite compact, with smaller leaves and shorter stems.

The other green, orange, yellow, and far-red light colors are the assisting drivers for photosynthesis and other morphological developments.   

II.    The Science of Light and Plant Growth

A. The Spectrum Of Light

The light spectrum can mean a combination of electromagnetic radiations encompassing a diverse range of color wavelengths and frequencies that contain energy fuel for all living organisms.

Horticulturists have traditionally separated these rays into distinct wavelengths, each corresponding to a specific color or type of electromagnetic radiation. red, orange, yellow, green, blue, indigo, and violet. We may call these the visible light spectrum or the popular photosynthesis active radiation (PAR)

Put together, the primary colors have unique properties and interactions with plant cells, triggering many biological processes.

 Visible Light Spectrum

It is the segment of the electromagnetic spectrum perceivable by the human eye. Typically, it covers wavelengths from approximately 380-750 nm, subdivided into the rainbow colors Red, orange, yellow, green, blue, indigo, and violet.  As you move forward from red to Violet, the wavelength decreases and energy increases.

More simply, this range of colors is most familiar to you as the human eye can perceive it easily under normal lighting conditions; hence, it’s termed the Visible Light spectrum.

How Plants Perceive Light

Have you ever wondered how plants respond to light without having a brain or an eyeball? Tell us tell you how the phenomena work.

Like the eye in the human, plants have a network of light-sensing photoreceptors or simply cells that respond to the light energy falling on them within these 380-750nm wavelengths. To be more precise, these cells in the leaves absorb most of the light to create food and adjust physiological processes accordingly.

The key photoreceptors of plants include phytochromes, cryptochromes, phototropins, and UV-B receptors that take light as stimuli to regulate their lifecycles and adjust to environmental conditions.

What is to be noted here is that these photoreceptors are distributed through different parts of the plants, such as stems, leaves, and roots, which, when activated by light, initiate signaling pathways, leading to changes in hormones, gene expression, and various other physiological alterations.

That is why processes like photosynthesis, photomorphogenesis, and the plant's circadian rhythm are observed.

For instance, when Phytochromes are activated by sensing red or far-red light, plants can use it as a clue for seed germination, seedling growth, and the regulation of flowering time.

Similarly, Phototrophins sense blue light and play a crucial role in stomatal opening and the bending of plant parts toward a light source. They also contribute to regulating chloroplast movement in response to light intensity.

All in all, they collectively allow the plants to sense the quality, quantity, and duration of light and help them optimize their growth and development.

B. Photosynthetically Active Radiation (PAR)

Light is solely a component of plant existence. But it’s more about its quality than the quantity. Plants, in general, use and absorb only a certain portion of the light spectrum, referred to as Photosynthetically Active Radiation.

PAR is the amount of light energy within the 400-700 nm wavelength range optimized for photosynthesis. This corresponds to the visible light spectrum that plants use for energy conversion. The energy photons of the PAR transform CO₂ + water into sugars and oxygen. Chlorophyll, the green pigment in leaves, absorbs the PAR energy.

Comprehending and adjusting PAR is a great way to optimize greenhouse lights, where natural sunlight may be limited. By tailoring PAR to the specific requirements of plants at various growth stages, growers can improve photosynthetic efficiency, enhance crop yields, and promote overall plant health.

III.    Impact of Different Light Colors on Plant Growth

The light coming from the sun, which we perceive as white, is actually a blend of different colors. The primary colors of light are red, blue, and green. It's quite tricky to give an exact answer for which color is better for indoor plant growth. Plants need both red and blue light with other wavelengths in the PAR spectrum. All these colors have different effects on plants. Let us explore them separately.

1. Blue Light

Blue light is the shortest wavelength in the spectrum, with wavelengths between 450 and 495 nanometers, directing the leaves and growth points to light. Blue photons are energetically more efficient, so ideally, a low amount of blue light is always advisable.

Blue light is linked to regulating the “stomata” of plants, the pores in leaves responsible for carbon dioxide intake and oxygen discharge. For photosynthesis to occur, there has to be sufficient blue light for optimal growing processes.

Blue light tends to regulate plant circadian rhythms, influencing various physiological and metabolic processes over a 24-hour period. This is the main reason plants produce secondary metabolites, including certain phytochemicals with potential medicinal or protective properties.

That said, blue wavelengths significantly influence leaf coloration and vegetative growth. The spectral energy can be extraordinarily beneficial in the development of compounds that accelerate the vitamin levels, quality, and overall healthiness of crops. Finally, blue light, serving as a regulator, can be used in conjunction with red light to increase the flowering of plants.

When farmers experimented with blue lights on plants, they found the plants to be healthier, stronger,  and wider than usual. This can be explained by the fact that it keeps plants dense and compact as they grow, which is suitable for indoor environments with limited space.

1. Red Light

Ranging from 600-700 nm, Red light impacts a plant in many ways. You can view its significance by witnessing an increase in the total size of the plant. When you expose your plants to plenty of red light, you may see them producing large, tall stems with plenty of branches.

As a fundamental component of the Photosynthetically Active Radiation (PAR) spectrum, red light is a key contributor to the process of photosynthesis. More specifically, this light is known as a facilitator of plants' flowering and fruiting stages, making it crucial for developing reproductive structures.

This is because the photoreceptor in plants absorbs a large quantity of red light, which increases the production of a plant hormone, meta-topolin. So, when horticulturists strategically use red light in conjunction with other spectral wavelengths, they observe maximize yields and ensure better health and vitality of cultivated plants.

However, using red light alone would ruin the growth, resulting in an elongated and stretched appearance with long, thin leaves. What you should do is grow with 80 to 90 percent red light and 10 to 20 percent blue light for better results.

1. Green Light

Falling between 500-600 nm, green light isn’t a primary driver for photosynthesis which is why, for many, it's an insignificant component of plant growth. but its significance lies in other morphological developments.

The reason why most plants appear green is the fact that plants reflect green light rather than absorb it, leaving green color behind.

Studies associate green light as an influential factor impacting stem elongation, leaf expansion, and flowering.

This light can reach deeper into the plant canopy to improve photosynthesis in chloroplasts located towards the bottom surface of the leaf and beyond; which is not the case with red and blue lights. This is a plus point for reaching lower leaves and promoting more uniform growth throughout the plant.

So, when you integrate green light with a full spectrum grow light source, you can create a more natural and visually appealing environment for plants.

1. Other Colors (Yellow, Orange, and Far-Red)

Yellow and orange lights are often overlooked in the spectrum of the PAR, but they also play their role in the plant development processes. Like the chlorophyll pigment absorbs blue and red light for photosynthesis, carotenoid pigment picks the orange and yellow color which then assists plants in absorbing light energy and transferring it to chlorophyll, enhancing overall photosynthetic efficiency.

Particularly, the orange light triggers the production of auxins, a growth hormone of plants linked with cell elongation and healthy plant growth.

As far as the Far-red light is concerned, It is found at the extreme end of the red spectrum, ranging from 700-850 nm. Although it exceeds the PAR spectrum or human perceivable wavelength, it is still slightly visible to the human eye.

For most obvious reasons, it doesn’t seem to be interacting with plants as ranging beyond the absorbable limit but this idea was offset when certain plants produce desirable results.

According to the latest findings, far-red light has the potential to increase or control plant growth when added to full-spectrum growth regimens.

More surprisingly, adding far red photons to a spectrum of shorter wavelengths produced an increase in canopy photosynthesis equal to adding additional light from the PAR range (400-700 nm) of the same intensity.

IV. Combining Different Light Colors

A. Full-Spectrum Lighting and Its Significance

Hearing the term “Full spectrum lighting” may remind you of the seller who claimed that they sell full spectrum led grow light when you intended to buy the artificial light source for your plants.

Yes, it’s something that has been at the forefront of lighting technology, especially in the horticulture realm.

To make you aware, Full spectrum grow Light refers to the completeness of light spectral energy. Simply put, it can ideally mean the wavelengths containing visible wavelength, extending into the ultraviolet (UV) and infrared (IR) regions, similar to natural sunlight.

The light’s ability to closely mimic the spectral distribution of sunlight provides plants with the necessary light wavelengths for optimal growth and development.

LED grow light full spectrum sources are designed to simulate sunlight and provide a balanced light spectrum for better visual perception, enhanced color appearance, and optimal physiological processes.

Its significance extends to various applications, including indoor plant growing, art studios, and photography. Moreover, it offers plants several benefits in the following perspectives.

Optimal Wavelength: A full spectrum grow light with the ability to emit a broad range of color wavelengths, including a good percentage of blue and red hues, paired with a moderate amount of other colors, is what gives plants their energy source. This helps plants increase their photosynthesis efficiency and steer plant physiological procedures, leading to compact, healthier, and sturdy growth, unlike plants grown under insufficient lighting conditions.

More Sunlight-Replicating Environment: The tendency of the light source to use PAR-spectrum light and the wavelengths outside of the 400-700 nm range means a more comprehensive lighting environment similar to what they would get outdoors. This significantly helps plants accelerate flowering, increase nutrition, and speed up the growth rate.

All-Year-Round Cultivations: The best part about full-spectrum grow light technology is that you won’t have to rely on sunlight to do your plant cultivations. This means your evergreen companions can be grown all year using these light sources.

All in one Package: Since full spectrum lighting fixtures give plants an entire spectrum of light to make chlorophyll, photosynthesis, and produce sugars, you don’t have to purchase one blue light and one red light separately, resulting in less money spent on artificial lighting. On top of it, if you integrate LED grow light in your growing setup, this even becomes advantageous in terms of saving on electricity consumption, cooling equipment, and spectrum controls.

V. Practical Applications and Considerations

Factors of Consideration for Indoor Gardening And Hydroponics

Lighting, at first, seems to be just like a simple thing for ordinary people. However, this can be a deceivingly complex topic for light designers or indoor horticulturists.

Lighting arrangements for houseplants, starting seeds, and nurturing plants aren’t just about placing full spectrum grow lights in the indoor growing setup rather, it calls for a thoughtful understanding of the plant species, their growth requirement at each stage, and lighting suitability in terms of duration, intensity, and quality.

This way, you can put together a healthy atmosphere for plants for successful and thriving growth.

For this, you may need to pay attention to the following elements.

The Light Quality: When light quality is discussed, it mainly refers to the composition of light as per wavelength or a correlative number of photons of green, red, blue, far red, and other light spectra emitted by a light source.

For assessing light quality, there is no universal standard to measure it. However, several aspects can be considered either qualitatively or quantitatively to conclude. The parameters include the Color Rendering Index, brightness, uniformity, and Color temperature.

Light Intensity: Light intensity can mean the brightness of light or the bulb's light output, usually measured in lumens. So, an increased lumen means more brightness and vice versa. The fact that light facilitates plants at every growth phase, optimal light intensity is a good sign to fuel their metabolic processes.

This energy is used not only for photosynthesis but also for various growth functions, including nutrient uptake and the synthesis of essential compounds.

Breaking down the light intensity for all plants isn’t justified. Every plant has its own tendency to grow with varying light requirements. However, you can manage to have low light intensity during the early stages of growth and as plants move forward, you can increase during the flowering.

The Color Rendering Index: It is a unit measurement of how well a light source accurately represents the colors of objects compared to a natural light source, typically daylight. Sun, in this case, is a leading winner with a CRI measurement of 100. So, if your bulbs indicate a CRI of 80-90, it's going to be well-accepted.

However, the concept of CRI is directly inapplicable to plants because it determines the human vision of colors rather than tailoring to plants' specific needs. The more relevant metric is the Photosynthetic Photon Flux Density (PPFD). This metric takes into account the wavelengths of light that are most important for photosynthesis and plant growth.

• A PPFD of 200-400 µmol/m²/s is often suitable for the vegetative stage when plants are establishing roots and developing leaves.
• a PPFD range of 400-600 µmol/m²/s is suitable for mature plants in the veg phase.
• A PPFD of 600-1000 µmol/m²/s or more is commonly recommended during flowering and fruiting.

Color Temperature: This metric indicates the characteristics of the grow light source, usually measured in Kelvin (K). it often encompasses the “coolness” and “warmness” of light and in plant context, it influences the spectral distribution and the growth pattern.

A low color temperature below 4000K with a yellow and red color appearance is generally warmer and fits well into a setup when the grower intends to promote fruiting or flowering in plants.

On the other hand, a Color temperature above 5000K is cooler appearing more blue and white, suitable for vegetative growth and other plant development.

To avoid confusion, A balanced spectrum, having both warm and cool light, is generally beneficial for overall plant health, and modern Full-Spectrum LED grow lights are designed to provide such a spectrum for optimal results.

Tips for Better Lighting Setups

Lighting quality in a given space always entails blending light source(s), customizable spectrum, adequate light duration, intensity, and crop species. This scenario makes it quite challenging to create a single formula that will always produce the perfect lighting for any given space. Fortunately, there are good-working full spectrum grow lights technology that makes your growing struggle much easier.

However, these practical tips that, when taken into consideration, can also be of great help. The following are a few examples.

• The first and foremost consideration is analyzing the crop species. Obviously, not every plant is the same, so getting to know plants’ varying light requirements is paramount. Some thrive in high-light conditions, while others prefer lower light levels. Research the specific needs of the growing plants to tailor your lighting setup accordingly. With dimmable LED grow lights,you can have multiple crops under a single light system. Isn’t that amazing?

• Next, Choose a grow light system that provides a balanced spectrum with sufficient red and blue wavelengths. Ideally, a full spectrum grows light is perfect to get your hands on as their spectral energy is distributed across the entire electromagnetic wavelength. So, you can fine-tune as per the demands of the plants.

• Make sure your lighting facilities in the grow room are spread evenly across the entire plant canopy. You can have a few small lighting chambers installed at some distance over the plants, or you may choose one large lighting panel. What goes suitable manage to have a uniformity of light throughout. Uneven lighting can lead to uneven growth and may affect overall plant health.

• Opt for a suitable grow light system depending on the growing space you’ve. As a general guideline, 25-50 watts per square foot goes well for small herbs and seedlings, whereas 50-75 watts per square foot is okay with a medium-sized setup. of grow light. When choosing a commercial-grade indoor growing setup, there is no better choice than the 1000 watt LED grow light.

• Go for lighting systems that allow spectrum adjustability, just like the FD-Series System. The Dimmable Switchfeature enables growers to adjust the light quality based on the specific needs of different growth stages.

• Establish a controlled or consistent photoperiod (the duration of light) to mimic natural daylengths. Plants in the vegetative stage thrive well in a longer day length, typically around 14 to 18 hours of light, but as they transit to flowering, the light exposure should be reduced to 10 to 12 hours.

• Knowing how far the grow lights be from plantsis another great concern. Position your fixtures at a correct distance from your plants to achieve the desired PPFD. You can fine-tune the placement by bringing lights closer or farther as required. Experts suggest fluorescent fixtures should be placed 6 to 12 inches from the foliage, and LEDs can usually be 12 to 24 inches away in most cases.

• Continually monitor plant responses to light. By this, we mean keeping an eye on the signs of heat stress, leaves tilting, plants turning yellow, or pest infestations.

• Lastly, plan to expose your gardening system to natural sunlight.

1. Conclusion

Wrapping things up! The impact of light color on plants is a fascinating interplay between plant biology and environmental science. The changing wavelengths from the high-energizing blues to the bud-promoting red and even far red in most cases, influence photosynthesis and other development processes.

Today, the gardening industry has come a long way from the days of traditional outdoor farming. The sunlight limitation during high temperatures and seasonal shifts has spurred many advancements in the agricultural sciences. Within the past century, farmers now know that they can directly impact and improve their crop’s growth, outcome, and overall yield by having Systems like LED grow lights or UV grow Light.

Understanding different grow light spectrums and their contribution to plant growth are some key learnings for cultivators to tailor light environments, ensuring the optimal performance of their green companions.