Full Spectrum LED Vs Red And Blue- The Truth You Need to Know

(Last Updated On: November 8, 2021)
Full Spectrum LED Vs Red And Blue

The best option available to present-day indoor growers is to use LED grow lights. Sounds simple enough, right? However, in reality, opting for LED lights is only the first step into the grow lights industry. Then you’ll have to choose whether to go for the full spectrum LED vs. red and blue spectrum LED bulbs.

These two spectra grow lights differ in the width of their spectrum. The red & blue spectrum is known as narrow bands because their emitted wavelengths are all within a limited range. But full-spectrum LEDs that emit white light are known as broad-spectrum LED grow light. That’s due to their inclusion of broader waves of the light spectrum.

Many indoor growers opt for the full spectrum LEDs over the red and blue spectrum. But as white light LEDs mimic the sun, that may not be the wisest decision. Rather, you should consider which light to use depending on the needs of your indoor garden.

Color Spectrum and Wavelengths

Color Spectrum and Wavelengths

To get the whole picture, we need to start from the basics. With that thought at hand, what is a color spectrum? It’s simply a graphical representation of each of the colors in the light.

While some of us may know only a few colors, there are so many different shades of colors that it becomes pretty complicated to refer to them by their name. That’s why scientists have found an easier way to address these colors.

Instead of referring to the colors by their name, scientists have assigned discreet numbers to them. And it’s much more accurate as well.

For example, if a color has a wavelength between 500 and 600, we call the color green. That’s because the color is supposedly in the same spectrum.

But in reality, each number is a different color in itself. That’s why scientists refer to them by using their wavelengths. For example, a color with a wavelength of 510 is entirely different from a color with a wavelength of 530.

While they may look exactly the same to the naked eye, in reality, they’re totally different colors!

 Read More: What Color Light is Best for Plant Growth

Grow Light Spectrum Chart

If you were to go a bit deep into the topic of grow lights and their efficiency, unquestionably, you must have come across their spectrum chart. Without any references to work with, grow light spectrum chart can be a bit of a puzzle.

Grow Light Spectrum Chart

For example, in our chart here, you can see different complicated terms. These include Photosynthetically Active Radiation or PAR and Relative Photosynthetic Efficiency.

The PAR rating measures how much light is available for the photosynthesis process. This light is within the band of 400 to 700 nanometers.

It’s in this range where the plants can use the light for photosynthesis. But if you only use the PAR rating as to your basis of judgment, you’ll end up with a wrong notion.

You see, wavelengths outside the PAR range also play a role in determining a plant’s growth. That’s why grow light spectrum charts include the PAR range, visible spectrum, and other spectrums.

To make a more precise indication of the efficiency rate of the different colors, the grow light spectrum chart uses the Relative Photosynthetic Efficiency on its y-axis.

As per the chart, we can see that the highest point of efficiency lies in the blue and red wavelengths in the PAR band. Blue light is considered to help plants’ growth in their flowering and vegetative state. It also helps them establish their structural growth.

At the same time, red light has the highest efficiency in driving up the photosynthesis process. This characteristic helps a few plants secure their biomass growth.

 Read More: How is Light Energy Converted into Chemical Energy during Photosynthesis

Grow Light Spectrum Type

Different colors trigger the growth characteristic in plants outside the PAR range. In fact, different plants are sensitive to different spectrums of light. And the amount of light they need to consume to trigger healthy growth differs as well.

To put it simply, different colors in the color spectrum can trigger different areas of growth. These areas include various fields like flavor, flowering, yield, color, and many more.

You need to know about the effects and applications of different spectrums in the growth system to get the best results.

UV Light Spectrum (100-400nm)

UV Light Spectrum (100-400nm)

Featuring a wavelength of 100 to 400 nanometers, the UV light spectrum is invisible to the human eye.

The PAR range starts from 400 nanometers. So it doesn’t include the Ultraviolet light spectrum. But since UV light constitutes almost 10% of the Sunlight, it’ll be our topic of discussion for now.

Overexposure to UV light can be harmful to the human body. In the same way, overexposure to UV can have quite a deleterious effect on plants as well. But, it can also offer some benefits to plants’ growth.

To make the subject more accessible, scientists have categorized UV rays into three distinct categories. They are UV-A (315 to 400 nanometers), UV-B (280 to 315 nanometers), and UV-C (100 to 280 nanometers).

While the research on UV light hasn’t been concluded yet, scientists have come up with several benefits that UV light offers.

For starters, did you know that small amounts of ultraviolet light can improve the nutritional value? Not only that, it can enhance the color, aroma, and taste of the plants and their fruits and flowers!

Moreover, you can also mitigate the effects of fungus, pests, and environmental stress with the help of a controlled amount of UV.

And if you’re an indoor farmer, UV light can revolutionize your whole business. According to researchers, UV light can increase your yields by tons!

Blue Light Spectrum (400-500nm)

Blue Light Spectrum (400-500nm)

The effects of the blue light spectrum are pretty well-known in the grow light industry.

Blue light assists in the stomatal opening in plants. As a result, they can take in more carbon dioxide through their leaves. In turn, it can enhance the plant quality of your yields, especially if the produce is leafy.

The blue spectrum can also enhance a plant’s ability to absorb chlorophyll pigment. The chlorophyll pigment is a necessary component of the photosynthesis process.

That’s why young plants and seedlings must have the required amount of exposure to blue light. That way, they can establish a healthy stem structure and root as a strong foundation.

 Read More: Why Does Blue Light Help Plants Grow

Green Light Spectrum (500-600nm)

Green Light Spectrum (500-600nm)

While the color green is associated with the word plants, the green light spectrum isn’t considered necessary for a plant’s growth.

However, it’s not that green light doesn’t help with the growth of plants. It’s just that the ability of green lights to absorb chlorophyll readily pales when compared to blue and red LED grow lights.

So, in the wild or an open field, plants do absorb green light for the photosynthesis process, but it’s only a minuscule (around 5 to 10 percent). That’s mainly because green light lacks the ability to penetrate a plant’s canopy.

So, it’s not strictly necessary for you to supplement the green light spectrum with LEDs when working in a grow room. That’s the case even with greenhouses due to their exposure to direct sunlight.

 Read More: How Well Would a Plant Grow Under Pure Yellow Light

Red Light Spectrum (600-700nm)

Red Light Spectrum (600-700nm)

The red light spectrum is the most effective spectrum for enhancing the photosynthesis process. Why is that? That’s because the red light spectrum sits at the top of the chlorophyll absorption catalyst.

To put it simply, red light helps the plants the most to absorb chlorophyll pigments.

But as we discussed earlier, there are different types of pigments in the red light spectrum. So, how would you know if your garden is getting the best exposure?

Here’s where the numbering system comes in handy. According to scientists, the red light with a wavelength of 660 nanometers can most enhance leaf growth, stem growth, and overall vegetative growth.

However, you have to keep in mind that red light will also cause your plants’ leaves and flowers to stretch. To ensure that they don’t overstretch, you need to provide a balanced pairing of the red light spectrum with the blue light spectrum, which specializes as a countering agent to overstretching. That way, you won’t end up with any overstretching problems, such as disfigure stem elongation.

So, while red light is critical to a plants’ growth, you have to keep in mind that it has to be done in moderation with a combined effort with the other colors in the PAR chart.

Far-red Light Spectrum (700-850nm)

Far-red Light Spectrum (700-850nm)

This deeper shade of red light or the far-red spectrum can have quite the effect on a plant’s growth. For example, far-red light can help trigger the plant’s shade-avoidance response.

To put it simply, it teaches the plant to recognize the shade of another plant. In turn, the plant tries to outgrow that shade, which can cause its growth to increase.

Far-red light has been proven to be quite helpful in triggering flowering, especially in short-day plants. These short-day plants rely on more prolonged periods of darkness, so you can use this spectrum of light to promote flowering. And in many cases, an increased yield has been observed. 

That’s why many growers are now experimenting with this band to promote their indoor garden’s flowering and growth.

Red and Blue LEDs

Red and Blue LEDs

The famous red and blue LEDs don’t emit the regular blue and red light separately. Instead, they give off a more purple or pink glow. That’s because these LED lights use different combinations of red and blue LEDs. The blue and red lights for plants use this combination to counteract any disfigurement problems.

Red light is the most efficient spectrum for photosynthesis. But if your garden is exposed to only this wavelength, it may result in poor growth, such as elongated stems.

Blue light is introduced into this system to keep such poor growth in check to counteract this problem. But you can’t ensure proper growth through blue LED grow light only.

If your plants receive only blue light, all the processes that take place due to exposure to red light will not take place. So, your garden will lack proper growth. And in the worst case, some might even die, which is a genuine possibility.

That’s why you need to maintain a proper balance of both the light spectrums to ensure healthy growth in your indoor garden.

But, what is the ideal mixture of both spectrums? Through years of research, scientists have found that a mix of a higher percentage of red LED grow light and a lower portion of blue light promotes the healthiest growth in plants that are already getting a sufficient amount of sunlight.

And since there’s no perfect spectrum for greenhouse plants (for now!), most LED manufacturing companies produce red and blue LED lights that offer a fixed ratio of red to blue light. This has been announced to be the most ideal for an indoor garden’s growth. 

Full-Spectrum White Lights

Full-Spectrum White Lights

When working in a greenhouse, the sunlight can balance out the pink/purple light LEDs emit. But that’s not the case when working on a smaller project or an entirely indoor project.

In fact, it can be pretty uncomfortable to work under such a narrow spectrum of light. That’s why many indoor farmers have chosen to shift from these narrow-band LEDs to the ‘white’ or full-spectrum LEDs.

While full-spectrum LEDs have a comparatively lower efficiency or effectiveness than red and blue LED lights, they seem to work better indoors. This lower efficacy rate is due to their energy, conversion, and optical losses within the lights’ phosphor conversion process.

But when indoors, the LEDs are the only light source. So the broad spectrum lights tend to be far more effective than their narrow-spectrum counterparts.

This phenomenon is because the broad-spectrum LEDs emit all the other wavelengths that the red and blue LEDs lack. While red and blue LEDs shine when they share the exposure to Sunlight, they can’t deliver the different wavelengths that your garden needs.

For example, the red and blue LED lights lack green lights, previously thought to be entirely unnecessary for your plants’ growth. However, as we’ve discussed earlier, while the green light has comparatively less effect on a plant’s growth, they’re not completely useless.

Moreover, due to the absence of different colors, you may not be able to recognize many problems such as pests, diseases, nutritional deficiency, and many more. That’s why it’s not only uncomfortable to work under red and blue lights but also more difficult to assess your garden’s condition.

 Read More: Purple Grow Light vs White Light

Problems With Full-Spectrum LED Grow Lights

To compare between red and blue grow lights vs. white LEDs, you need to know their flaws. The concept of the full spectrum is flawed from the start.

For starters, the name full-spectrum is quite misleading. Just because you call it full-spectrum LED doesn’t make it so. There are three major problems with full-spectrum LEDs that you should be aware of.

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Not Optimized for Plants

One of the main problems with most broad-spectrum LED grow lights is a flaw in their design. While they’re designed to appear as if they’re giving off the same light as the sun, most of them aren’t customized to fulfill the needs of a plant’s growth.

In our earlier discussion, we’ve seen that not all light spectrums can promote the photosynthesis process. Some specific colors or wavelengths can help promote healthy growth in a plant’s life. It doesn’t matter if the light is bright or not.

Regardless of that fact, many manufacturing companies produce grow lights with only visual appeal in their mind. As a result, they tend not to be helpful in a plant’s growth.

Doesn’t Include the Full Solar Spectrum

The theory behind full-spectrum LED grow lights is that if they could produce a grow light that can create a spectral distribution that can imitate the Sun’s, your plants can really benefit from that. Sounds simple enough, right? However, it’s not!

The supposedly full-spectrum LED lights don’t really include all the wavelengths as the Sun’s. Sunlight is a complex idea. Scientists are still doing their research on it, and they have a long way to go, even if they can get their heads around the whole idea.

So, it’s unfair of us to expect that they can create something that can imitate the bright shining star in the sky.

The manufacturers try to include the PAR spectrums in the grow light system as they tend to be the most important ones for the photosynthesis process. However, plants still respond to the other spectrums in the light.

The Sun gives off many other light spectrums such as infrared light, UV light, and many more. Some of these are not even visible light. So, it’s only logical that those responses triggered by these other wavelengths will not occur under the influence of LED grow lights.

Given the current technology, if you want to create a light source that can initiate the same responses, it’d be impossible to build such a light source. And even if you could create such a light source, it’d be way too expensive to gain any profit!

Not Dynamic like the Sun

As we said earlier, it would be way too expensive to build a light source that can imitate the sun. But even then, it would lack one of the vital characteristics that make Sunlight so ideal for a plant’s growth.

What makes sunlight so unique is that it is dynamic. It’s in constant flux due to changes in its relative position or weather. The sunlight spectrum changes throughout the day and in different weather conditions.

So, if you were to get such a grow light, you wouldn’t be able to imitate the dynamic nature of the Sun. Reaping the benefits (and also the drawbacks) may not be possible indoors. But that doesn’t mean that you should move your garden outdoors.

For starters, your plants don’t need infrared light to live. Yes, they’ll miss out on some of the benefits that nature offers, but that also means that they won’t have to face those disadvantages.

Full Spectrum LED Vs Red And Blue- What’s Their Difference?

The main difference between full-spectrum LEDs and red and blue LEDs lies in their wavelength.

Red and blue LED grow lights tend to be known as the narrowband spectrum. But the full-spectrum or white light LEDs tend to be known as broad-spectrum light. That’s because the full-spectrum LEDs’ light emitted includes a broad band of wavelengths, which is why the full-spectrum luminaires give off a white glow.

Keep in mind that there are not many other differences between the two types of LEDs. They even share the same production method, except that the full-spectrum LED lights’ production method includes one more step.

After red and blue LED lights come out of their production method, the manufacturers then cover them in a phosphor layer that converts the narrow wavelengths into longer wavelengths by absorbing the blue light. The phosphor coating absorbs the blue light particles and then emits most photons into red and green light.

Notice that we said most, not all! That’s because some energy becomes lost in the conversion process due to the phosphor coating’s light absorption.

As the coating reduces the LED’s efficiency rate when converting the photons into the helpful PAR range. The composition of the phosphor can help you to find out the quality of the emitted white light.

 Read More: COB Vs. Quantum Board LED Grow Lights

Is There An Ideal Spectrum for Your Plant?

So, the burning topic in front of us is whether there’s an ideal spectrum for your plant. The answer is a simple one. There’s no one perfect targeted spectrum ideal for your plant’s growth.

It largely depends on the nature of your project and your applications. So, if you’re looking for a perfect spectrum, there’s no such thing. That’s because different plants respond differently to different wavelengths.

Researchers have observed that different crops have different growth responses to varying wavelengths of the light spectrum. So, to get the best result, you’ll need to run a trial run and see how your plants respond to different wavelengths.

Since you can manipulate the generated growth response through the different spectrums, you need to determine what growth characteristics are the most important to you.

In most cases, growers want to maximize their profits with greater yields and crop quality. If your primary target aligns with this one, you won’t necessarily need a particular light spectrum to do the job.

But many growers tend to be confused about whether they need different spectrums for the various stages of growth, such as vegetative, flowering, or production phase.

Before LED grow lights came into being, the norm was to use CMH or ceramic metal halide for the vegetative growth phase. And since HPS or high-pressure Sodium lights are suitable for flowering cycles, growers would usually use HPS lights for those plants in their flowering stage.

But you won’t need such separate systems when working with LED lights. That’s the beauty of LED grow lights!

You don’t need to care about the amount of light produced. All you need is to maintain the duration of light exposure to get specific growth responses and the intensity of the light that they’re exposed to.

For example, as your plant species move from the propagation phase to vegetative growth to the flowering stage, you’ll need to increase the light intensity to maximize crop yields. It’ll also enhance the quality of your yields.

So, in a sense, you can say that light intensity is directly related to the yield and quality of your crop yield.

 Read More: How many LED lumens Per Plant

Frequently Asked Questions

Is red and blue light full-spectrum?

There are two main differences between full-spectrum lights and red and blue peaks.

The first is based on their emitted wavelengths. The wavelengths emitted from red and blue LED grow lights belong to the narrow bands. Whereas the wavelengths that full-spectrum or white light LEDs emit belong to the broader spectrum. That’s why they’re also known as broad-spectrum LEDs.

Secondly, while both types of LED grow lights share the same production method, full-spectrum lighting systems include a phosphor coating that their red and blue counterparts lack.

So, all in all, red and blue light aren’t full spectrum.

Are full spectrum grow lights better?

There’s no single perfect LED lighting for everyone. It all depends upon your application and the nature of your project.

For example, if you’re working in a greenhouse or where the plants get direct sunlight, red and blue LED grow lights should work the best. But if your grow light will be the primary source of light, you’ll face some problems working with red and blue grow lights.

First of all, working under such a narrow band spectrum can be pretty uncomfortable. Secondly, it’s rather difficult to assess your plant’s health under red and blue grow light.

In such a situation where your grow light is the primary source of light, you’re better off working with full-spectrum grow lights.

What color LED grow light is best?

Researchers say that a balanced combination of red and blue light works best for the plant’s growth. And if there are tiny amounts of green and yellow light, even better. However, you need to ensure that the amount of exposure and the light intensity is thought out.

For example, in the mixture of red and blue light for plants, the percentage of red light for plants should be relatively higher than the percentage of blue light. That way, your plant’s light absorption would be a full-proof plan, paving your way to success.

What is the difference between a grow light and a full spectrum light?

The easiest way to answer this question is that all full-spectrum grow lights are grow lights, but not all grow lights are full spectrum.

Standard grow lights, or fluorescent lights, tend to emit light in the blue light spectrum. Incandescent grow lights emit light in the red light spectrum. On the other hand, full-spectrum light fixtures cast a light similar to the natural sunlight, which appears as though it’s white.

 Read More: Can Any LED Light be Used as A Grow Light

What does blue light do for plants?

The blue light spectrum directly affects chlorophyll production. If your indoor garden has enough exposure to blue light, it’ll have plants with healthy and strong stems and leaves.

Moreover, it also helps to counteract the overstretching problem. By using blue light, you can eliminate any disfigurement problem in plants.

 What does red light do for plants?

Red light directly works to regulate the development and growth of plants. If your indoor plants don’t have sufficient exposure to the red light fixtures, they’ll not grow healthy.

Moreover, this light spectrum helps a plant bear fruit and flowers. It also helps them prolong the flowering phase in the growth cycle of growing plants.

And last but not least, red light can help improve the photosynthesis process in plants. In turn, it can enhance their growth.

Do red and blue led grow lights work?

Scientists have concluded that a balanced combination of red and blue LED light is the best for a plant’s growth. You’ll get even better results if they have enough exposure to natural light.

So, we’d say that red and blue LED grow lights do work. In fact, they’re the most energy-efficient grow lights in the industry.

Full Spectrum LED Vs Red And Blue – Final Words

With the emergence of the revolutionary LED grow light, the potential of the growing industry has grown exponentially. To ensure such growth, you need to know which type suits best for your application.

As a general rule, if your grow room has direct exposure to sunlight, such as in a greenhouse, red and blue LEDs should work the best for you. But if your grow light is your single source of light, then full-spectrum LED luminaires should be your first choice.

You should do your research to decide between full-spectrum LED vs. red and blue LEDs. Only then can you pave your path to success in the growing business. Happy gardening!

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