Plants need light for photosynthesis and growth. However, not all light is useful to plants. In fact, some are outrightly harmful and dangerous to them.

Is UV light useful or harmful to plants? That’s the question this article aims to answer.

But first, what is UV light? An ultraviolet ray is that part of the electromagnetic spectrum which falls between the visible light and X-rays. They are usually found within the 400 and 10-nanometer wavelength.

Due to its shorter wavelength and higher frequency, we are unable to perceive the spectrum – this high energy property of the UV light also impacts plants we will see later in the article.

What are the different types of UV light?

Ultra-violet light for plants are grouped into three categories based on their wavelength, and they include:

UV-A light (wavelength 320 -400nm): This UV light has the longest wavelength and is the least harmful, mainly used in products like nail lamps or UV flashlights.

UV-B light (wavelength 290 – 320nm): This particular UV light causes cellular damage both in humans and plants. About 95 percent of this UV type is absorbed by the Ozone layer.

UV-C light (wavelength 100 – 290nm): this UV light is extremely harmful and thankfully, absorbed by the earth’s atmosphere. UVC is the light used in sterilization processes, present in products like air purifiers or germicidal wands.


Effects of UV light on plants

Plants respond to the different types of UV. However, various plants react differently to the UV light with differing outcomes.

Several studies have highlighted the effects of UV light on plants, and unfortunately, they are mostly negative.

UV light causes DNA damage – due to its high energy the genetic materials of the plants are altered resulting in mutations or cell apoptosis – a situation where cells fight against it to protect itself from damage.

On the other hand, DNA damage may not be viewed as negative but rather as an evolutionary force that leads to the development of more diverse and sturdy crops able to withstand changes in the environment.

Triggers plant photomorphogenic responses – studies have shown that low-level UVB induces photomorphogenic reactions in some plants – photomorphogenic response is the ability of plants to sense light and grow towards it – which aid in their growth.

Lipid peroxidation – UV lights trigger free radicals which in turn destroy cell membranes resulting in cell damage.

UV is detrimental to plant microbes – Micro-organisms are an essential part of a plant’s life cycle – either for good or bad. For instance, some bacteria cause plants diseases such as wilt and rust while others like the nitrogen-fixing microbes play a crucial role in supplying plant nutrients, aiding plant growth and repairing damaged cells,

Now, ultra-violet lights are incredibly harmful to these microbes and usually leads to their death. Though it can kill off harmful bacteria, it also impacts the useful ones, hence destroying any mutual relationship between the plants and the microbes.

UV light might lead to the development of UV-resistant crops – With climate change becoming an increasing threat to global food production, scientists are driven to develop plants that are able to withstand exposure to UV lights.

Do plants need UV light?

The answer is Yes. Plants don’t require UV light to photosynthesize their food. The reason is that UV light falls within the electromagnetic spectrum which is outside the visible or photosynthetic active radiation band. However, there are multiple benefits of UV-A light on plants:

  • UV-A can increase plants yields – according to a recent study, plants will grow bigger and faster, because of the impact of UV light on them.
  • UV-A can increase the level of nutrients from plants, therefore, plants will be tastier.
  • no doubt, UV-A will make plants more resistant to fungal infections.
  • recent studies revealed that UV-a light has a great impact on plants change growth pattern, chemistry, and transpiration processes.
  • Full Spectrum LED Grow Lights which include UV light as well will help plants grow as they were harvested outdoors.

In conclusion

There is no doubt that at its core, ultraviolet light is harmful to crops; however, this does not negate the fact that it is a positive force in driving innovation for developing adaptive plants that can withstand harsher conditions, thereby ensuring food security for humanity.


  1. So basically, UV light harms plants, but in doing so, it makes them more enjoyable to us. I guess it’s the same as the effect on us. UV light damages our skin, but in doing so, it makes it nicer to look at for a lot of people.


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