Can UV Grow Light Help Your Plants?

Can UV Grow Light Help Your Plants

Greenhouses using the UV grow light look cool, don’t they? Actually, the income they bring will be handsome as well. We all know that plants cannot live without light, and lights of different colors have distinctive influences on plants. For example, red light and blue light are essential because these two lights can help with the photosynthesis of plants. Besides red and blue light, UV light can also have an unexpected effect on plants. Continue reading and learn more about it!

Which UV light is used for UV grow light?

UV light consists of UVA, UVB, and UVC and is divided this way depending on their different wavelengths. The wavelength of UVA is the longest, which is 315-400nm. UVA is the closest to visible light and is also called near UV light. UVB has a wavelength of 280-315nm, and people call it middle UV light. UVC, the far UV light, has a wavelength of 100-280nm. It is the most powerful of these three lights and can cause more harm than UVA and UVB lights. To find more details, you can take a look at the previous blog, What Is A UV LED.

UVC light has more energy than the other two lights, but people don’t use it for grow lights. Even though UVC has the ability to sterilize the surface of leaves, it also has side effects. It can destroy the DNA structure of organisms, so it is possible that plants are not safe under UVC light. Thus, when it comes to UV grow lights, we use UVA and UVB lights. We will talk about their functions in the following sections.

Lights and the growth of plants


You must be familiar with this concept, as we all learned about it in school. Plants need food, which they produce by themselves through photosynthesis. The very beginning of this progress is to absorb light. Then chlorophyll functions to combine carbon dioxide and water to produce glucose and oxygen molecules. How can we increase the nutrition plants produce? People think from two angles. The first is to prolong the time of illumination by artificial grow lights. This way, plants can also do photosynthesis during the night. Second, people try to make the lights that are helpful for photosynthesis purer. Normally, the plants absorb the sunlight, which contains the whole spectrum. But not all light is necessary. For instance, green light has little value for prompting the growth of plants. To make photosynthesis most effective, red and blue light are best. When designing the UV grow light, people also consider the above two perspectives.



Some plants have the trait of phototropism. They try to grow toward the light source to ensure the leaves receive maximum light for photosynthesis. The sunflower is the most famous example. Thus, according to the direction of light, the plants may grow into different shapes. Moreover, the light also changes the status of plants. In summer and spring, with plenty of light, most plants focus on growing, blooming, and setting fruit. As winter approaches, when light intensity and duration decrease, plants will focus more on conserving energy and growing less. So we can use grow lights to make plants grow even in winter.

Effect of the UV grow light

Now we know several principles of the growth of plants. Then what are the specific effects of the UV grow light? You can check out the information below:

Better photosynthesis

Besides using red and blue lights as grow lights directly, UV grow lights can also be a choice to provide red and blue light. UV grow light achieves this because of its high energy. When certain amounts of UV light shine on the plants, the leaves will reflect the light. Every time, the light will lose a little energy and change into one with longer wavelengths. In this way, it can become blue light and then red light. And since it contains much energy at the beginning, even though it is reflected, the intensity of light the plants receive will still be higher than that created by grow lights of a single color.


Through assisting photosynthesis, the UV grow light makes the plants more prolific. Besides, it can also boost the production of other nutritious substances. Experts have found that UVA light can increase crop yield and promote the synthesis of proteins, sugars, acids, and secondary metabolites. This is a result of the reaction between UV light and the proteins on the leaves. When plants receive UV light, their stress responses will occur, which makes them produce more essential nutrition. You will be able to harvest heavier plants with bigger leaves after using the UV grow light.

Treating diseases

Where there are plants, there are insects and bacteria. Although we cannot use UVC because it may also hurt beneficial bacteria, UVA and UVB lights can also perform as sterilizers sometimes. For example, the UV grow light is effective in eliminating viruses and molds to treat common diseases like powdery mildew. They can reduce harmful substances both on the surface and in the air.


How to use the UV grow light?

There are many things to which you should pay attention when using the UV grow light. Setting the UV grow light at some casual locations and turning it on for 24 hours will not help your plants grow. Here are some tips to help you use the UV grow light correctly.

Q: Is the best way to use UV grow light the same for every type of plant?

A: No. Although you can use the UV grow light for almost every type of plant, they need light of different intensities and duration to achieve the best yield. Now experts have found that under the UV grow light, plants like leaf lettuce, cucumbers, and peppermint will grow greener and bigger leaves, proving the universal use of the UV grow light. But they all have their own way to grow, so you need to decide how you will use the UV grow light depending on the species.

Q: Where should I place my UV grow light?

A: Careful placement of grow lights is also important to better simulate ideal sunlight conditions. There is no doubt that placing lights above plant beds is a relatively good idea. It will help expose all sides and leaves of the plants to the UV grow light. What’s more, an appropriate distance should be kept according to the type of grow lights. As for the UV grow lights, since they dissipate little heat, you can hang them at a height of 20-40 inches from the plant canopy.


Q: Can I turn on the UV grow light for 24 hours?

A: No. It is not feasible to keep the light on 24/7 because the dark environment is also very important for the growth of plants. Plants need a light-dark cycle to thrive. The amount of light they need varies from species to species. For instance, corn loves relatively short-term light. 8-12 hours of light will promote its growth, while 12-14 hours will be too much. So it is necessary for you to search for or ask for the experience of other people.

About Mokolight

Here at Mokolight, we have various grow lights, and our staff will help you find the best one suitable for your plants. Except for grow lights, we also provide different kinds of UV lights. All these LED lights are guaranteed by our own factories, international certifications, and our 16+ year experience. Contact Us and get the best service ever!

Written by ——
Scott Hughes
Scott Hughes
Double Bachelor's degrees in Architecture and Electrical Engineering, 5+ years of experience with LED lighting, intelligent moving lights, and conventional fixtures. Reach Me Now>>
Scott Hughes
Scott Hughes
Double Bachelor's degrees in Architecture and Electrical Engineering, 5+ years of experience with LED lighting, intelligent moving lights, and conventional fixtures. Reach Me Now>>
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