do indoor plants need uv light
Indoor Growing

Do Indoor Plants Need UV Light?

UV light has always remained a hot topic for debate when it comes to indoor plants and indoor grow lights. There are misconceptions and myths that create much confusion for beginners. It is a component of natural sunlight, but we still have questions about its effects on plants, whether it is harmful or not.

In this article, we will have an in-depth look at UV light, its benefits and effects on plants, and how you can give your plants UV light. We will discuss different types of UV light to know which are beneficial for your plants.

What is UV Light?

UV light refers to Ultraviolet electromagnetic radiations that are present in the sunlight. Its wavelength is less while the frequency is more than the violet radiations present in the visible range, which is why it is known as UV or Ultraviolet.

The light coming from the sun is composed of three types of radiation: Ultraviolet, Visible, and Infrared radiation. Surprisingly, 8% of the total radiation of sunlight is ultraviolet.

uv light

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The human eye can only see visible radiations, and ultraviolet and infrared radiations are not visible to the naked eye. With that being said, UV light is present in the sunlight, but we cannot see it.

More precisely, the electromagnetic radiations having a wavelength in the range of 10-400 nanometers are called UV light or Ultraviolet radiations.

Classification of UV Light

The complete range of wavelengths of UV light is 10-400 nanometers. But the range of 100-400 nanometers is classified into three types.

  • 1.UVA
  • 2.UVB
  • 3.UVC

All these types of UV lights have their advantages and disadvantages related to their effect on plants. Let's see which is the best UV light for plants.

uv light spectrum

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1) UVA

The first classification of UV light is UVA which has a wavelength range of 315-400 nanometers.

Out of all three types of UV light, UVA reaches Earth in abundance because it has the ability to pass through the ozone layer. It is more than 98% of the total UV light that reaches Earth.

Although it is the least dangerous type of UV light, it can cause skin cancer.

However, it is the best UV light for indoor plants. It does not damage the plant's DNA and harm plants in any way; instead, it offers various benefits, such as protection from fungi and molds.

The wavelength range of UVA light is relatively higher than UVB and UVC and is more penetrative. But the frequency of UVA is less than all; consequently, the energy is also less. It can easily pass through a glass but can be blocked by sunscreen.

Plants should get UVA light because it is quite beneficial and has no side effects. It is beneficial to introduce UVA to your indoor plants. Your indoor plants can also get UVA light through LED grow lights and other sources.

2) UVB

UVB has a wavelength range of 280-315 nanometers, which is a narrow range compared to UVA.

Most of the UVB radiation is absorbed by the Earth's atmosphere. It helps in the conversion of oxygen to ozone, which is why most of it is consumed by the atmosphere. But it reaches the ground in a meager amount.

UVB is necessary for the production of Vitamin D in humans. When human skin is exposed to UVB light, Vitamin D is produced. Thus, it is beneficial for humans, and humans need it. However long-term exposure to UVB is harmful. It can cause skin cancer and skin burns.

UVB is quite beneficial for plants. It can improve the color and other properties of a plant. Most importantly, it acts as a natural pesticide that protects from microorganisms.

Undoubtedly, UVB is beneficial for plants, but too much exposure can change the DNA of some plants. It must be introduced to plants within limits. You can get UVB light for plants from grow lights.

3) UVC

The wavelength of UVC light ranges from 100-280 nanometers, which is the widest range compared to other types. It has the lowest wavelength and highest frequency.

UVC is the most dangerous UV light, but fortunately, it is blocked by Earth's atmosphere. The ozone layer absorbs all UV radiation, and nothing is left to reach land. Thus, the sunlight we get does not contain UVC. However, UVC can still be produced artificially using various methods.

Plants do not need UVC, and it does not benefit them at all. However, UVC can be used for sterilization, but it must be used with care; otherwise, it can damage plants and harm people working in the area. It damages the DNA of plants in no time.

UVC is dangerous for humans as well. It causes burns and damages the eyes. Even slight exposure to UVC is quite harmful. The worst part is that sunscreens cannot stop UVC.

Benefits of UV Lights for Indoor Plants

Better Growth

Exposure to UV light to plants improves overall growth. It speeds up photosynthesis, which leads to faster growth, especially in growing tent.

If UV light is given under safe limits, it can improve the growth, including the size and weight of the leaf and flower.

Specifically, UVA increases the leaf size and improves biomass production in plants. According to a study on lettuce, when UVA is supplied to the plant, 15-19% higher shoot dry weight is observed. It increases biomass production to optimum conditions.

According to the study, the shape and growth of lettuce plants were greatly improved when UVA light was introduced. The best result was obtained when the UVA was 10 µmol m−2 s−1. When it was increased to 30 µmol m−2 s−1, the outcome was not as promising but was still better than no UVA.

plants under uv light

The surface area of the lettuce plant was 402.7 ± 15.9 cm2 g−1 when there was no UVA. At UVA-10, the surface area was much better, 435.1 ± 18.6 cm2 g−1. It was noticed that the surface area was reduced in the case of UVA-20 and UVA-30, but it was still better than the condition that was in no UVA.

There was also a significant effect on the shoot dry weight. It was 1.77 ± 0.10c g plant−1 in no UVA condition. The result in UVA-10 was 2.24 ± 0.11a g plant−1 and UVA-20 was 2.29 ± 0.09a g plant−1. It got reduced a bit in UVA-30, 2.03 ± 0.12b g plant−1.

Thus, UVA can improve plants' growth, size, and weight if given in selective levels.

Improved Quality

The quality of plants is greatly improved by UV light. It improves the weight, flavor, size, and aroma of the plants. Overall, taste and smell are improved if given in a controlled amount.

UV rays also help in the production of resin, which is immensely beneficial for the potency of various plants. Consequently, the quality of the flowers is greatly improved through UV. 

The resin production in plants affects various qualities, including aroma and flavor. Therefore, commercial growers prefer UV light to improve the quality and yield of the harvest.

In the study, the nutritional quality of lettuce was improved along with biomass production after the introduction of UVA. It indicates not only the growth rate and size are improved, but the nutritional value is also enhanced.

Protects Plants

Plants that do not get UV light are more prone to pest attacks and microorganisms. UV light helps plants protect themselves.

Due to the introduction of UV light, the plant produces more resin that protects them from pests. There are various proteins produced after the introduction of UV light; consequently, the plant is saved from harmful organisms.

How Can You Give UV Light to Your Indoor Plants?

In your grow room, you can use grow lights to get UV lights for plants. You might be thinking about which grow lights you can use.

As far as the UV light is concerned, LED grow lights, fluorescent lights, and HID lights produce UV lights. You can use any of them for UV; however, all of them have distinct benefits and features.

LED Grow Lights

The best option for indoor growers, including commercial growers, is LED grow lights. The reason behind the wide usage of these lights is their extraordinary features.

LED grow lights are the most efficient grow lights; around 90% of the electrical energy is converted into light which reduces the heat emission. Due to high efficiency, it saves energy and reduces electricity bills.

As there is low heat emission, the indoor grow area is not too hot, and there is no harm to the plants.

LED grow lights are costly, but they have a long lifespan. They last for a long time, which is beneficial for commercial growers.

LED grow lights emit UV and IR radiation. But if you want more control over UV or IR, there should be separate bars in the light. Spectrum X contains two UV+IR bars that give you more control over the radiation. You can ensure optimal growth by using this UV LED light for plants.

uv light bars

It is difficult to find a separate arrangement for UV and IR in other types of grow lights. LED grow lights are much better than other grow lights in all aspects. The only problem is that they are costly, but the cost is easily recovered as they are efficient and long-lasting.

Fluorescent Lights

For beginners, fluorescent lights are often suitable as they are cheap. They are more efficient than incandescent bulbs and less efficient than LED lights.

 fluorescent light

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Fluorescent lights ionize the mercury vapors in a glass tube of any shape or size. Due to ionization, UV radiations are produced. Since we cannot see UV light, it is converted into visible range using phosphor, the white coating inside the tube.

UV light is converted into visible light, but still, there are radiations present. T5 grow lights are widespread fluorescent lights for indoor grow rooms.

HID Grow Lights

High-intensity Discharge (HID) grow lights are extraordinarily powerful lights that emit too much heat energy. They are pretty bright, and extra care is needed to avoid leaf burns.

These lights are older than LED grow lights and are less efficient. But they give off UV light that can be used for plants.

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