UVA/UVB Lights For Plants

Sharing is caring!

Last Updated on February 21, 2023

Even though most of our knowledge on ultraviolet light seems to be undesirable, a bit of ultraviolet light is still safe. UV light is divided into 3 groups according to their wavelengths and are UVA, UVB, and UVC. In this post, we will be discussing if UVA/UVB lights are good for plants.

As a grower, you should have an idea of the exposure of ultraviolet light on your plants and how the growth of your plants. So, let’s dive in and explore how UVA/UVB lights affect the growth of your plants.

Ultra Violet Lights & Their Types

Ultraviolet light is electromagnetic radiation which has radiation shorter than visible light and is present in the sun.

There are 3 different types of ultraviolet lights and they include:

  1. UVA: the ultraviolet A wavelength ranges from 320 to 400nm. The natural light that passes through the earth is made up of 3% UVA light. UVA light makes up most of the entire amount of UV light on the earth. You should however know that UVA lights for plants do not cause DNA impairment.
  2. UVB: the wavelength of the ultraviolet B ranges from 290 to 320nm. It makes up about 0.15% of natural the entire sunlight. The UVB light rays are capable of causing damage to the DNA of cells and they can as well cause cancer in living cells. The good news is that nearly all of the sun’s UVB rays are obstructed by the Earth’s ozone layer.
  3. UVC: the wavelength of ultraviolet C ranges from 100 to 290nm. The UVC light is extremely energetic and it’s capable of killing living cells. It is even used for sterilization uses to kill harmful microorganisms. Fortunately, UVC light rays are filtered out entirely from the Earth’s surroundings.

VIVOSUN 48″x24″x60″ Grow Tent with Observation Window and Floor Tray

Among these 3 ultraviolet lights, only UVA and UVB are used in little doses by plants. So, let’s take a look at how UVA and UVB play their roles in plants.

Benefits Of UVA/UVB Lights For Plants

Various plants respond in different ways when they are exposed to UVA/UVB lights. Below are some benefits UVA/UVB lights offer plants:

  • Antioxidant Production: Generally, it’s been shown that plants enjoy an increase in antioxidants or flavonoids production.
  • Enhance TCH & CBD: Also, both UVA and UVB in safe doses offer your plants that awesome flavor and smell from the oil they produce. The effect of UVA and UVB has been shown to enhance the production of THC and CBD in certain plants.
  • Trichomes Production: The same way humans make use of sunglasses or sunblock to protect from the rays of UV, plants as well produce their natural sunblock or sunscreen. The sunblock plants produce is known as trichomes and the more the trichome production, the more the THC and CBD range.

  • Enhance Germination: The germination process of indoor seeds that are just starting can be promoted by ultraviolet lights.
  • Reduces Plant Shock: When your plants are still indoors germinating, they are still fragile to high light intensity. If you transplant them from indoors to outdoor, they might go into shock. This is because the light intensity outdoor may be too high for them to adjust. But when you expose them to a few UV lights when they are indoors germinating in their early stage, shock from outdoor transplanting can be reduced drastically.

UV Lights In Grow Lights

Most of the grow light available contains the entire visible spectrum and a few ultraviolet lights. This way, this uva uvb grow lights duplicate the natural sunlight in a very close range. However, you should know not all grow light contains ultraviolet light.

Too Much UVA/UVB Light For Plants

As we have said in a low dose, ultraviolet lights are safe for plants. However, when they become too much, they will cause harm to your plants.

Ensure your indoor plants are kept safe from the rays of outdoor lights. Ultraviolet lights can penetrate through your glass windows and cause harm to your plants if they are not positioned properly. So, ensure you keep your fragile plants far from the reach of the light rays. You can as well obtain some dark thick curtains to block out the ultraviolet rays.

Too Much UVA-UVB Light For Plants


Do plants need UVA and UVB light?

The answer to this question is yes. The ultraviolet (UV) spectrum is divided into two parts: ultraviolet-A (UVA) and ultraviolet-B (UVB). Plants use both of these parts of the spectrum for different purposes. UVA is a part of the visible light spectrum that we see as white or yellowish light. It is a component of sunlight and is not filtered by clouds or the atmosphere.

UVA is used by plants for photosynthesis and other cellular functions. UVB is the part of the spectrum that is filtered out by the atmosphere and clouds. Plants cannot use this portion of the spectrum for photosynthesis or other biological functions. UVB is important to plants because it causes plant tissue to darken. This causes damage to plant cells and can result in sunburns, which can be painful and cause skin damage if the exposure is too long. UVA radiation (wavelengths 400 nm to 320 nm) penetrates the atmosphere and can reach the surface of the earth. This penetration is dependent upon the amount of ozone and the wavelength of the UVA light. The UVB radiation (wavelengths 320 nm to 280 nm) penetrates the atmosphere and does not penetrate the stratosphere. This penetration is dependent upon the amount of ozone in the stratosphere.

The UVB part of the spectrum is filtered out of sunlight by the atmosphere. As a result, the UVB radiation we receive at ground level is relatively small.

What plant needs both of these?

The only plants that I know that require both UVA and UVB are the blueberry. The blueberry needs a lot of UVA and UVB to flower and fruit. It can't flower or fruit if it doesn't get enough UVA and UVB.

Do grow lights have UVA and UVB?

Yes, grow lights have both ultraviolet (UV) A and ultraviolet (UV) B wavelengths. UV-B is the most harmful of these wavelengths, and can cause a sunburn on your plants, but UV-A is actually beneficial to plants. It causes plants to open their stomata, or pores, which allows air and carbon dioxide in and water out. Without this, the plant would be suffocating.

Do LED grow lights produce UVB?

There is a myth in the cannabis community that LED grow lights do not produce ultraviolet B (UVB) light. This is false. It is one of the most common questions we get asked by people who are new to growing cannabis indoors. UVB is known as the “sunlight” of the plant world, and it’s essential for flowering. UVB light is produced by plants in sunlight.

Conclusion On UVA/UVB Lights For Plants

So, we have concluded that ultraviolet lights are safe in minimal doses for plant growth. Both UVA and UVB in safe doses can offer your plants good benefits.

Sharing is caring!