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How UV Lights Helps With Plant Growth


Plants are living, breathing organisms. Like us humans, they need the perfect conditions to survive, grow and thrive.

We all remember learning about photosynthesis at school, right? Well, while plants use water and soil for nutrients, they use light to create energy. 

The sun produces light for all forms of life on earth, and the varying types of radiation are situated on something called ‘the electromagnetic spectrum’. The spectrum is broken into three categories: Ultraviolet, visible, and infrared radiation. 

Plants absorb the light through photons, and use it to convert carbon dioxide into the food and energy they need. 

However, UV and infrared isn’t good for plants in high doses. In fact, it can have a less than positive effect on the plants – so it can be tricky to get the correct balance.

This guide we’ll discuss how UV light can affect the health of your plants, and how you can ensure your plants stay healthy during all stages of the growth cycle. 


Ultraviolet light is electromagnetic radiation produced by the sun. It’s the very thing responsible for your tan – or your sunburn. It’s invisible to the human eye and has the shortest wavelength on the spectrum, between 100 to 400 nano meters. Most of the light is absorbed by the stratosphere before it reaches earth – which is fortunate as it is damaging to living tissue – (hence the red glow you enjoy while on holiday…) 

Due to only 7-9% of the radiation reaching earth, UV doesn’t have a substantial effect on the growth and health of plants in their natural habitat. However, in more controlled environments, like in commercial gardening, UV can have a detrimental impact on growth and yield.

UV radiation effect on microbes and organisms

Microscopic organisms, or microbes, have an important role to play in the life of a plant. Some microbes have a negative impact on your plant, but some can be positive - nevertheless - UV radiation kills them off. 

The death of these organisms means a change in the composition of the materials that the plant uses to make its food supply. Whilst the bad bacteria - which can cause plants to wilt, rust or contract disease - are destroyed, so is the good, nitrogen-fixing microbes which help increase the amount of usable nitrogen. 

UV radiation effect on cell apoptosis

Ultraviolet radiation can also cause DNA damage to a life form which, can produce varying degrees of mutation for your plants. UV-R damage can cause the DNA to mutate, or it instigates ‘cell apoptosis’ – where the cell buries itself to protect it from further damage. 

That said, DNA mutation isn’t necessarily a bad thing: Mutations strengthen immunity and allow stronger organisms to survive. Some mutations evoke ‘controlled cell apoptosis’, where plants learn to harvest and replace aging organs with new ones. 

Whilst the earth’s ozone layer continues to be damaged by UV, scientists have found that crops are beginning to evolve to block their own DNA being damaged. As a result, crops are now able to withstand drier periods and more challenging climates while using the light to fight bacteria in the soil.  


To use UV light to your advantage, you need to find a way to unlock only the positives, where your plants are forced to adapt. 

The best way to do this is to use a UV grow light that contains UV diodes. (Our recommendation would be the 4Seasons UV 385nm LED Grow Light) Ensuring this will provide your plants with enough UV light to aid their growth, without completely destroying them. 

Why you shouldn’t invest in UVB LED grow light

There are a lot of studies and rumours on the internet that insist you need a UVB LED grow light to ensure maximum growth. This is all fake news. Ultimately, it’s not worth the money you’ll have to stump up for it.

UVB diodes are extremely expensive, and usually have a UVB fluorescent bulb attached to them. These cost you more in energy, for very little added benefit. 


Some people consider black lights as an alternative that will have a similar effect. Black lights only emit a small amount of UV-A, ultimately meaning plants don’t grow as well. To use a black light within the grow space, you’ll need additional lighting to promote growth. 

Reptile lights are also recommended. These lights don’t contribute to plant growth, but can help trigger plant mutations and cell apoptosis. 

Difference between reptile lights and black lights

The difference between the two is the type of UV they emit, with reptile lights providing UV-B and black lights emitting UV-A. Ultimately, neither light will boost the growth of your crop.

Understanding the impact UV can have on your plants is tough. You’ll need to balance along a fine line of too much, and too little to ensure your plants are getting just the right amount to thrive. 

If you need help with finding the perfect grow lights for plants or have any questions about how to produce bigger yields, don’t hesitate to get in touch!