Impact of UV and IR lights on cannabis
By Photonican | 15 March 2023 | 0 Comments

Impact of UV and IR lights on cannabis

In daily life, you may have heard that infrared light and ultraviolet light are usually used in cannabis cultivation, but the information about it collected on the Internet is very scattered. In this article, we will give you a clear introduction to infrared light, ultraviolet light, and their impact on cannabis cultivation.

  1. What is ultraviolet light?
  2. Impact of ultraviolet light on cannabis
  3. What is infrared light?
  4. Impact of infrared light on cannabis
1. What is ultraviolet light?
UV-A light (315 - 420 nm): UV-A light has the longest wavelength and the lowest energy in the UV spectrum. Sunlight contains a lot of UV-A light and most plants planted outdoor are exposed to UV-A for a long time. Studies have shown that UV-A does not damage the DNA of most plants.
UV-B light (280nm-315nm): sunlight contains UV-B light. If plants are exposed to UV-B light for a long time in the natural environment, their DNA will be damaged and then produce many defensive chemicals to protect themselves from sunlight. UV-B damages plants in much the same way as it damages human skin getting burned.
UV-C light (below 280nm): UV-C light has the shortest wavelength and the largest energy in the UV spectrum. It can lead to sunburn in humans, destroy the DNA of plants, and directly kill bacteria and insects on the surface of plants and humans. However, most of the UV-C light emitted by the sun is absorbed by the atmosphere, and only a small amount is in the sun.

2. Impact of ultraviolet light on cannabis plants

(1)Increase cannabinoids

Exposed to the sunlight containing ultraviolet light ( mostly UV-A / UV-B), cannabis planted outdoor will grow more trichomes to protect itself from ultraviolet light.
Cannabinoid is produced by trichomes, the more trichomes, the more cannabinoid. If cannabis is exposed to ultraviolet light indoors, it will have the same effect as planting cannabis outdoors.
However, if you are cultivating strains specifically for CBD, please avoid using UV-B.
Because the more THC cannabis produces, the less CBD they produce, and vice versa. 



(2) Reduce pest infestation
Many plant growth lights manufacturers claim that ultraviolet light can directly kill insects, but this is wrong. The only ultraviolet light that can directly kill insects is UV-C, and we have mentioned that UV-C (200-280nm) has the shortest wavelength but the largest energy, which will cause injuries to people and plants. If expose UV-C to cannabis, probably both insects and cannabis will be killed.
We already know that exposing UV-A/UV-B to cannabis will help them produce more cannabinoids.What we may don’t know is that cannabinoids are also called defensive chemicals. They can drive away the pests,and protect cannabis from being harmed by pests, such as powdery mildew.


Tip for using UV light:
Some growers use UV-A / UV-B light bars to radiate their cannabis plants to get more THC and reduce pest damage. Usually ,growers will expose UVA or UVB to cannabis for 1-2 hours per day in the last three or four weeks of the stage of flowering.
However, Exposing UV-A/UV-B to cannabis for a long time may be harmful, because UV-A/UV-B will pass through the plant's natural defense system and then inhibit photosynthesis, slow down the growth of cannabis plants, and destroy the DNA of cannabis cells, resulting in physical damage to cannabis plants, affecting the appearance and growth of plants, and even death. 
In addition, because UV light is harmful to the human body, necessary precautions must be taken to protect ourselves when exposed to UV light.

1. What is infrared light?
Near-infrared light(700-2000nm): Near-infrared light has the shortest wavelength in the infrared spectrum. The red light will usually contain a small amount of near-infrared light because it is closest to the wavelength range of visible red light. Near-infrared light is used for TV remote control.
Mid-infrared light(3000-5000nm): Mid-infrared is warmer than near-infrared and will not harm plants. Mid-infrared is usually used by scientists and astronomers in astronomy.
Far-infrared light(8000-14000nm): Far-infrared light is the hottest. It is usually used in plant cultivation.


2. Impact of infrared light on cannabis
The photoreceptors called phytochrome in cannabis play a role in the flowering, height growth, and photosynthetic rate of plants. When the plant is exposed to far red light, photoreceptors can sense it. But far-infrared light will not work alone on cannabis, it will affect the plant when combined with other visible lights such as red light and blue light.

(1) Reduce the time to bloom
According to the experimental results, far-infrared light will reduce the time required for plants to bloom.  When exposing red and blue light combined with far-infrared light to cannabis, it will shorten the time for switching from a vegetative state to a flowering state.

(2) Emerson effect - cannabis grows faster
In 1957, Robert Emerson found that if plants were exposed to far-infrared light and red light, the rate of photosynthesis of plants would increase.
But when he exposed the plant only to far-infrared light or red light alone, the rate of photosynthesis was lower.
Based on the Emerson effect, If exposing far-infrared light and red light to cannabis, the rate of photosynthesis of the plant would increase which means it will grow faster.
In fact, many growers use this method in cannabis cultivation. They say It can really help cannabis grow faster.
(3) Shade avoidance response - Cannabis grows higher and its flowers and leaves also grow wider.
If the ratio of red light and far-infrared light exposed to cannabis is rationally high, cannabis can sense that it is not in an ideal position, and then it will grow higher and stretch its flowers and leaves to receive more light. So if we expose far-infrared light and red light to cannabis instead of red light alone ,the cannabis will grow higher and its flowers and leaves grow wider.
However, the ratio of red light and far-infrared light exposed to cannabis being too high will lead to the leaves and flower of cannabis growing and stretching too much, and then putting too much pressure on the stems of the cannabis finally causing the cannabis to die.

Tip for using Far-infrared light:
Some growers will expose far-infrared light to cannabis before turning off the led white light for about 120 minutes in the last two weeks of the stage of flowering
It may be harmful to cannabis if far-infrared light is exposed to cannabis for a long time because it delivers heat to cannabis. Heat is dangerous to cannabis because it can turn their leaves yellow and even kill plants. What’s more, if there is too much heat in the planting environment, it will take a lot of electricity fees to use a cooling machine to keep the temperature appropriate.
In addition, far-infrared light may be harmful to cannabis seedlings. Exposing far-infrared light to cannabis may for  hinder the seeds to germinate completely.
Therefore, for plants to grow healthily, it is necessary to choose a far-infrared light bar with an appropriate amount of far-infrared light and use it in the right way.

Check out the video : What’s more,our spectrum provide at least 30% more red spectrum output than most similar LED grow lights on the market,which can boosts for more yields and increases cycles in a year.

Leave a Reply

Your email address will not be published.Required fields are marked. *
Verification code