Uncovering the Truth Behind Full-spectrum White LED Grow Lights

If you are an indoor grower, choosing the right light is paramount to obtaining a high yield and being cost-efficient. Oversaturation of the market with several brands and manufacturers is a reality. They all offer different types of grow lights for our gardening projects. Among these, full-spectrum white LED grow lights generate constant discussion among growers. Are they better? Will they help you produce healthier plants?

Many people, growers included, think white LED lights are similar to sunlight or sunlight spectrum, a copy of the ideal light delivered by our sun. While this is a debatable topic, what is true is that various color spectra generate a significantly different response in plants. Factual evidence suggests plants need red and blue light the most. However, at the same time, green and yellow wavelengths, while not absorbed as much, remain essential.

Which one is better – a spectrum of white light or a specific wavelength? Many reviews claim one is more effective than the other, but which is correct? In this article, we will be taking a deeper look at full-spectrum white LED grow lights to understand if they can be an effective tool for indoor growing.

What Is “White Light”?

Technically speaking, white is not a spectral color. Our eyes are only able to perceive three colors: red, green, and blue. That is what the color-sensitive cones inside our eyes can discern from light. Any light that stimulates the three cones at a similar level will appear white to us. Regardless of the presence of other colors, equal amounts of red, green, and blue will always appear as white. How we perceive the rest of the colors will depend on the combination of these three component colors. For example, purple light can arise from the stimulation of both the red and blue cones.

The electroluminescent technology of LED lights is not able to produce white light from its diodes. A light-emitting diode, known as LED for short, can only produce one color of light. A combination of red, green, and blue LEDs in equal measure delivers what appears as white to our eyes. If you were to view something that only reflects purple or orange, it would appear as black instead because there is no true orange or purple coming from the light source.

The vast majority of the LED white lights are blue LEDs with a coating made out of phosphor. This layer can convert blue light into a variety of different colors. The name of this phosphor is yttrium aluminum garnet (YAG), and it creates a yellow light (for the most part.) Thanks to the broader spectrum from the phosphor, it results in a white light that is perfectly suited to lighting up indoor areas at home or in the office.

Lights that work with the white LED spectrum include colors like red and blue within them. Other color wavelengths may also be present but at different intensities. “Full-spectrum” comes into play to describe an electric light source that covers all wavelengths of the electromagnetic spectrum. The ratio of these wavelengths is not necessarily the same in all fixtures and can vary from source to source, but it is important to understand that all white LED grow lights tend to mimic the look of natural light.

Are White LED Lights Beneficial to Our Indoor Gardening Projects?

It depends. Manufacturers of white LED lamps generally include a large amount of green and yellow light so that their LED chips can score high in the lumen rating. The lumen rating is a scale that measures the amount of visible light to the human eye. Our eyes mostly pick up green and yellow wavelengths in the spectrum of white light. The higher the lumen rating manufacturers get, the better their light fixtures will be at illuminating spaces.

Nevertheless, when speaking strictly about LED lights for plant growth, these may not always be the better choice. The yellow and green wavelengths play an important role in plant development, but their effectiveness is considerably smaller than that of the red and blue wavelengths. These last two colors within the white spectrum are vital if we want to make our plants grow as lushly and beautifully as possible.

Photosynthesis is critical in a plant’s development and growth. Several pigments inside the plant exist to absorb light. Among these, green chlorophyll A and B are two that matter a lot. These two collect energy from blue and red lights, whereas green light ends up being reflected. Depending on the biology of the plant, blue and red lights may result in a more significant morphogenetic effect, boosting the plant’s growth. That is not to say plants do not use green at all. Accessory pigments like carotene and xanthophyll both absorb certain levels of green light.

A problem here is that a simple white LED light lacks ultraviolet, infrared, and far-red spectrums, all extremely helpful in plant development. These wavelengths are outside the visible range and are completely absent from standard white light lamps

“Blurple” for Life

Targeted-spectrum is another LED grow light for plants scheme worth considering. Most diodes manufactured by the lighting industry tend to favor green and yellow spectrums. Since the regular amount produced by white LED lights far exceeds what’s absorbed by the plant, about 50% of that light ends up reflected onto the plant’s surface.

This wasted energy then turns into heat, effectively raising the temperature of the growing environment. Needless to say, this heat can have a detrimental effect, even damaging trichome production in the plant. Not to mention, it could also force the grower to invest money in cooling equipment.

Full-spectrum lights may replicate the sun to a pretty nice degree, but that doesn’t mean we want to deal with the inconvenience of having multiple “balls of nuclear energy” inside our growing environment, raising the temperature of our plants, and making our utility bills shoot through the roof. Instead of wasting all this energy, why don’t we focus our efforts on a spectrum that is good for the plants and our pockets, too? That is the idea behind these targeted-spectrum alternatives, and they work!

With a targeted-spectrum LED, your fixtures will decrease the amount of energy wasted by limiting the amount of green and yellow light wavelengths delivered to your plant. Reduced heat generated by the plant’s photosynthetic processes will mean less need for cooling equipment, which will also considerably lower your utility bills. Additionally, the presence of UV diodes also boosts the resin production of the plant to create more trichomes. These trichomes result in livelier-looking plants in the long run.

Since the most prominent pigments of the plant crave red and blue light wavelengths, that is where targeted-spectrum LED lights aim. These light fixtures produce a purple glow. This is why they’re referred to as “blurple” by many growers. Many traditional growers out there consider them the best lights for growing. Unlike other LED lights, their express purpose is for maximized plant growth. However, just like full-spectrum lights, their efficiency is relative and will depend largely on the gardening project you want to undertake.

Effects on Plants: White-light vs. Blue-light

What light fixtures and grow lights we should use will vary depending on what we want to grow. According to research, the white LED light spectrum can be great for plants when used in conjunction with other colored LEDs. Here, full-spectrum LEDs come in handy. Traditionally, growers used high-intensity bulb lamps to light their indoor gardens and plants.

However, using these often resulted in hot environments that were more of a headache to manage than anything. As a result, plant light analysis has been strong in recent years to find a way to incorporate full-spectrum white in a way that benefits both the growers and the plants.

Indoor growing often uses red and blue lights in conjunction with white lights. This results in an improved rate of light absorption and plants that develop more healthily and strongly. A study from the American Society for Horticultural Science reaffirms that some amount of blue light is indeed necessary for the plant’s development.

The amount of blue light needed is species-dependent and changes considerably from plant to plant. Using blue light with a significant presence of red and far-red ratios can affect the stem elongation and leaf size of a plant’s morphology. Studies like this are vital in showing how light quantity and quality directly affect a plant’s growth.

Understanding these interactions between light and plants becomes essential for growers. As mentioned earlier, not all plants react and grow similarly after prolonged exposure to concentrated red and blue spectrum wavelengths. Action spectrum and absorption spectrum are also crucial factors to consider. The former is the range of wavelengths used in light-dependent reactions. The latter refers to the degree of light wavelengths absorbed by chloroplast pigments inside the plant.

Take cannabis growth as an example. Seedlings from this plant need less light and instead grow better the whiter the light is. A light that is too intense on the blue or red spectrum can be detrimental to the plant’s development during its early stages. Once it moves into the vegetative stage, it requires less white light and more blue light for improved photosynthesis. Finally, when the cannabis plant reaches the flowering stage, a red wavelength is recommended for a better photosynthetic response.

How Light Temperature Affects Growth

Can white LED lights grow plants? Of course they can! Within the white LED light spectrum, differentiation occurs between light color temperatures. Cool, warm, and neutral white affect plant growth in a veritable way. White light sources are categorized either in Kelvin (K) or correlated color temperature (CCT). In this sense, we have:

• Cool white (6500K, 6000K, 5000K), which is more bluish and greenish to our eyes
• Warm white (4000K, 3000K, 2700K, 2000K), which has a more yellow or orange look

Different kinds of white exist among color temperatures, and the differences noticed may be entirely subjective from person to person. Doing measurements with a spectrometer will show a spectrum graph and photon distribution. Even spectra of the same white light color can have utterly different spectrum graphs, so take notice.

Nowadays, white LED grow lights can emit light in all of the visible wavelengths. The amount of white wavelength you get will depend on the color temperature of the light. For instance, if you want to obtain more blue wavelengths, you need to get a cool white light with a color temperature of 6500K. If you wish to get more red wavelengths, a warm white LED with a temperature of 3000K will be in order.

The temperature of the light can be easily adjusted by adding a thicker layer of phosphor and by modifying the wavelength of the blue LED beneath the phosphor coating. With this in consideration, let’s see the white light benefits we can get and where it would be ideal to use these different color temperatures in an indoor garden scenario:

• 2700K – 3500K

These lower color temperatures are of a warm white LED spectrum with more red wavelengths than a cooler light. These warm white LED colors are the best for making plants flower. The lower the color temperature, the better it is for flowering.

• 3500K – 5000K

This is more of a neutral white light but still contains a nice amount of warmness. Keeping it around 4000K or lower works great for lighting flowers. LED lights (soft white) such as this are the go-to option for proper illumination in a flower garden.

• 5000K – 6500K

A more neutral white LED is excellent for growing plants but falls short at making them flower. If you want your plants to bloom in a more splendorous fashion, then a warmer color temperature than this would work best. If you wish to do vegging, this white light Kelvin works great too. Of course, it will perform better for vegging the higher the Kelvin is.

• Over 6500K

Here’s a cool white light. Anything above this range is strictly for vegging or cloning plants only. The less red it contains, the more ideal it will be to dedicate this light exclusively to vegging.

Other Considerations

Some lighting companies try to provide a close match to the sunlight or daylight spectrum conditions. If the match is good enough for the plant, this will result in an indoor-grown phenotype comparable to the ones found outside. Here, covering the right wavelengths matters the most as the proper nanometer range will exclude wavelengths that don’t provide any tangible benefits to plants.

Finally, when discussing LED grow light for plants, CRI, or coloring rendering index, can be an important factor to consider as well. This measures how realistically the colors of an object appear under a light source. A coefficient from 0 to 100 determines if objects are visually well rendered, with 0 meaning the colors are not realistic at all and 100 indicating it would render as precise as it would under clear sunlight.

When working under LED lights that favor the red and blue spectrum and everything appears purplish around you, you will want to make sure the plants look naturally to your eyes to assess their situation. Here is when lights with a high CRI rating can be incredibly useful to have.

Final Thoughts

Are LED lights good for plants? They are! They are a vital part of any indoor growing project so that plants can develop healthily and happily while being part of the absorbable spectrum. Nevertheless, focusing entirely on one kind of light is not the way to go if your garden has a variety of plants. Their nurturing works better when we combine lights of different spectrums, namely red and blue. Here, full-spectrum white LED grow lights perform immensely well.

These are the best lights for growing and can provide outstanding response and growing strength to plants in the very early stage of development. Once a plant reaches a fully developed state, what works best is to tailor a specific spectral output adapted to the absorption spectrum of the plant. Providing too much blue or red spectrum can also negatively affect the plant, stunting its later growth. As such, finding the perfect balance of light remains essential to ensure it can keep growing efficiently.

Overall, cool white LEDs may be the best light source because of their high percentage of the blue spectrum. Not only are these more electrically efficient and able to keep temperature lower (hence reducing the need for external cooling equipment,) but they also prove to be necessary for the plant’s growth during its later life cycle. In the end, though, it will all depend on the garden you have. Check and study your plants thoroughly to choose a lighting solution that best suits your needs.

Leave a comment