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Medic Grow LED Grow Lights / News / What Is Full Spectrum LED Lighting?
What Is Full Spectrum LED Lighting?

What Is Full Spectrum LED Lighting?


Currently, there isn't a standard definition for "full spectrum light.”  Most customers are unaware of what they should expect whenever they purchase a light of this sort. It's also sad to note that some marketers take advantage of their customers' ignorance to sell substandard lighting systems.

For the sake of this article, we have come up with a suitable definition that encompasses what you should expect.

Full spectrum lights are lights possessing a 6500K color temperature, a CRI of greater or equal to 95, and closely mimic natural daylight in terms of spectrum.

Definition of Spectrum

By definition, the light spectrum is a part of an electromagnetic spectrum that is visible to the human eye. To fully understand this concept, it is essential to analyze the science behind light, in terms of spectrum, visible light, and radiation.

The term "electromagnetic spectrum" is a broad term that comprises all kinds of electromagnetic radiation – it factors in all the light ranges (the majority are not visible to the naked eye). The spectrum begins on the left with gamma rays and ends with long radio waves on the right of the visible spectrum.


Plant lights for indoor growing come in different wavelengths. The question is, "what are wavelengths, and how do they affect your selection for the best Full spectrum light?”

First, the wavelength is a scientific term that refers to the horizontal distance between to crests of a wave. One way to measure light is by using wavelengths, and visible light has a wavelength between 400-700 nanometers.

Visible and Invisible Light

Most electromagnetic radiations are defined with reference to visible light. This would naturally pop up a question like, “is there any such thing as invisible light?” The answer is simple. Radiations that cannot be perceived by the naked eye are invisible, while others that manifest as colors are in the visible spectrum.

The visible spectrum is bounded on the left by Gamma rays, UV rays, and X-rays. It is also bo8nded to the left by Infrared rays, Microwaves, Long radio waves, and radio waves. In all, the visible spectrum is a stand-alone concept from which other rays draw reference.

To accurately mimic natural sunlight, LED plant grow lights must have the requisite lights in the visible spectrum. The most crucial characteristic of the visible light spectrum is color, which is demonstrated by the seven colors of the rainbow.

These colors represent varying wavelengths, and as you move from violet to red, the wavelength increases and the energy decreases. From longest to shortest, here are the seven wavelengths in the visible spectrum:

Image Source: Wikipedia.com

UV Light

When you get sunburn, it is because of ultraviolet radiation. UV light is located next to visible light, and has a higher frequency, meaning it has higher radiation. Even with the drawbacks of UV light as electromagnetic radiation, it is still relevant in many ways. Some of these include remote controls, night vision, and thermal imaging. However, they are harmful to DNA and are seldom used as LED plant grow lights.

Sources of Visible Light

The importance of visible lights to the growth of cannabis plants cannot be underemphasized. These lights come in different wavelengths and are adequate for specific kinds of plants. Most times, the best full-spectrum LED grow lights tend to incorporate all the relevant wavelengths, depending o what growers seek to achieve.

Where Can We Get Visible Light?

This is a valid question, as not all growers can afford to depend on sunlight or plant outdoors. Indoor-grown plants require artificial lighting that will serve the same purpose as the sun in terms of lighting. Here are a few sources of visible light:

    • High-intensity Discharge – these electrical gas-discharge lamps produce lights using an electric arc between the tungsten electrodes. These electrodes are housed in a fused alumina arc tube or a transparent/translucent fused quartz.
    • LASER
    • Halogen – illumination is generated when heat is applied to a tungsten filament to emit incandescence or light. Halogen gas helps to increase the output of light in this case.
    • LEDLED is a two-lead semiconductor kind of light source which emits light when it is activated. Here, an electric current flows through a microchip that proceeds to illuminate very tiny light sources (LEDs), resulting in visible light. LED devices can transmit many kinds of radiation, from UV rays to visible infrared radiation. Most full-spectrum LED lights come in the form of LEDs.

Dr.MJ Coco has released his new video and explained the Science of LED.

  • Incandescent Light Bulb – an incandescent light bulb is an electric light whose wire filament is heated to such an intensity that it glows visibly.
  • Fluorescent
  • Sunlight – This is the chief source of visible light, and an ideal full spectrum light mimics sunlight.

What Kind of Spectrum Is Required For Growing Cannabis?

First, we need to understand what a PAR range means. Plants have a substance that helps them to trap light for photosynthesis. This substance is called chlorophyll. The PAR range is used in light spectrum charts to highlight the kind of wavelengths that could be trapped by chlorophyll to allow for plant development ultimately.

It has been observed that the zenith of photosynthetic energy falls in the blue and red-light spectrums of this range. For driving photosynthesis, the red spectrum/light is considered to be the most efficient. This light is crucial for plants at the flowering stage as it helps to stimulate biomass growth (which is paramount to cannabis growers). On the other hand, blue light is crucial for both the flowering and vegetative stages of plant growth. However, it is more useful for structural and vegetative growth.

Ideal Grow Light Spectrum for Marijuana

Full spectrum grow light is a priceless gem in terms of stimulating crucial aspects of growth for your plant. However, they will only be able to determine the growth of plants when several other factors are in place. For instance, some plants use the PAR-spectrum kind of light for photosynthesis and then use a wavelength beyond the 400-700nm range. This kind of full-spectrum light can help to accelerate the rate of growth, increase nutrition, and speed up flowering.

Take the Spectrum of the Spectrum Y Wireless for example:

In general terms, at blue and red peaks, photosynthesis is maximal; which means plants absorb these lights as they grow. Based on the facts stated for full spectrum lights, it is possible to think that the perfect grow light has the same spectrum as natural sunlight. However, it is much more than this.

Natural sunlight not only produces red and blue lights but also generates many orange, yellow and green lights. Studies have shown that although plants do not absorb green light (this is why plants are green), they need it for photosynthesis. As a general rule, light spectrums outside the red and blue wavelengths are the least used by plants for growth, like the red and blue wavelengths. An LED grow light is only as efficient as its ability to tune and adjust the wavelength needed for your plant.   

Grow Light Spectrum and Cannabis

Image Source:(IG)@spacementgrown

For cannabis plants, there needs to be special attention paid to the kind of light spectrum they are exposed to. This is because certain qualities must be gotten while they grow, or else the growing session becomes profitless. Some of these qualities include THC levels, yields, and production of other cannabinoid substances.

Apart from visible colors in the visible light spectrum, cannabis also responds to light w          outside the PAR wavelength. So, the best kind of grow light to use for cannabis is the full spectrum grow light, especially because of the ability to use specific doses or UV wavelengths (100-400nm), & far-infrared wavelengths (700-850nm) beyond the PAR range.

For instance, increasing the infrared wavelength can help to stimulate Cannabis flowering and stem growth. This is what growers want. However, in minimal amounts, essential blue light can hinder uneven stem elongation and leaf shrinkage.

In a nutshell, there isn’t a standard for what the ideal full-spectrum light should be. However, the best full-spectrum LED grow lights must have the necessary and adjustable wavelengths needed to stimulate your plant’s growth at different stages.

LED Grow Light Spectrum Based on Types

To get maximum yields, you need to adjust the wavelengths hitting your plants. It is also to identify that specific growth factors are a part of a larger complex cycle. Here are some light spectrum types and what they can do to your plants.

  • Blue light

This spectrum is essential for leafy crops, as it is generally responsible for increasing plant quality. It helps with stomatal opening, allowing more carbon dioxide entry into the leaves. Blue light drives maximum chlorophyll pigment absorption, needed for photosynthesis.

Blue lights also help young plants in their vegetative stages to establish a healthy rooting system, especially when stretching must be reduced.

  • Green Light

Only 5-10% of green wavelengths are reflected from off the plants; the rest is absorbed and transmitted down. All this is due to the ability of green light to penetrate the canopy of plants. It won’t be necessary to use green light in greenhouse settings compared to plants grown indoors.

  • Red Light

It is the most effective light that encourages photosynthesis, as it is highly absorbed by chlorophyll pigments. This wavelength promotes leaf, stem, and vegetative growth – but most importantly, the development of stretching of leaves and flowers.

Pairing red and blue lights is essential to stop overstretching – disfigured stem elongation. Although the red spectrum is the most effective wavelength, it only becomes potent when combined with blue light or other PAR wavelengths.

Other Common Questions

What are broad-spectrum LED Grow Lights?

These are LED grow lights that have a higher broadband LED ratio. They are white lights with no wavelengths. The white in question is a mixture of green, red, and blue wavebands. Broad-spectrum LEDs don’t mimic sunlight but can easily replace sunlight to stimulate crop development and give-off high crop yields in any environment.

How to find the right grow light?

There is a lot of science we could explore regarding full-spectrum lights and their undeniable importance. However, one key point to note is that your choice of a lighting system must be based on h    ow it can affect plant yields.

At Medicgrow, we constantly research and make available the best LED grow lights for your cannabis planting. Our LED systems are designed using detailed scientific information and features to help you control the wavelengths and have the ideal lighting setting.