UV Lights for Indoor Plant Growth: A Comprehensive Guide

There’s some debate about whether UV light is important for plants. Some growers even question if ultraviolet light is useful in plant cultivation at all.
The truth is, if you’re growing plants indoors, you should give them some UV light.
We’ll explain everything you need to know about UV light and how to use it in your grow room.

What is UV Light?
Ultraviolet (UV) light is a type of electromagnetic radiation that comes from natural sunlight.
Whenever you’re in the sun, you’re exposed to UV light.
UV light is divided into three categories of wavelengths: UVA, UVB, and UVC.
UV light helps plants grow in various ways and can improve the quality and potency of your flowers.
However, only certain types of UV light are beneficial to plants.

The Different Types of UV Light
UVA and UVB are essential for life on Earth, but UVC is not. The ozone layer filters out UVC, so it doesn’t reach our plants naturally.
For plants, we only need to focus on UVA and UVB.
Let’s look at the wavelengths of each type of light.
Ultraviolet A (UVA)
UVA light has wavelengths between 320 nm and 400 nm. It does not harm DNA.
Ultraviolet B (UVB)
UVB light has wavelengths between 290 nm and 320 nm.
Unlike UVA, UVB can damage DNA and has been linked to cancer in humans and animals.
However, the ozone layer blocks most UVB, so it rarely reaches Earth in harmful amounts.

How Does UV Light Affect Plants?
Plants respond differently to UV light based on its type and wavelength. The response also varies by plant species.

Here are some benefits of adding UV light to your plants

Higher Flower Quality & Weight
Studies show UVA and UVB light can boost the production of terpenes and flavonoids in plants.
In one study, tomatoes grown without UV light tasted bland. Adding UV light improved their flavor and aroma.
For those growing flowers, this means better taste and aroma.
UV light can also increase the resins and oils in plants grown for these compounds, making the flowers more potent and valuable.
UV light can also lead to bigger root systems, more branches, less stretching, tighter nodes, and heavier harvests.
Increased Resistance To Stress & Disease
UV light can help plants resist stress and disease. When exposed to UV light, plants produce up to 15 different defence proteins.
UV light can destroy harmful microorganisms, especially those with wavelengths shorter than 300 nm.
It also makes plants more resistant to bacteria, insects, and fungi.
Growing plants indoors without UV light means missing out on these benefits.
Faster Germination
UV light can speed up seed germination and help plants grow stronger and adapt to higher light levels.
This reduces the “shock” time for seedlings and speeds up their growth.

When Should You Give Plants UV Light?
Some growers think UV light is only useful during flowering and not during the vegetative stage. They believe it’s a waste of money.
However, if you want a strong, healthy plant, you should use UV light throughout the entire growth cycle, from seed to harvest. This helps the plant develop thicker cuticles, faster metabolism, and overall better health.
Using low doses of UV light throughout the plant’s life is safer and more effective than high doses at certain times.

Can UV Light Be Harmful To Plants?
There are many benefits to using UV light for plants, but can it be harmful? As long as you use the right kind of UV light, your plants will be safe. Use lights designed specifically for growing plants.

How Much UV Light Do Plants Need?
Plants need very little UV light. Less is more. You can get good results with just 1 watts of UV light per square foot of growing space. For example, in a 4’x4′ tent, you only need 16 watts of UV light.

Growers Need To Stay Safe While Using UV Light
While UV light is safe for plants, it can be harmful to you. Artificial UV light can be more damaging to your skin than the sun because you are closer to it. Always wear protective eyewear and sleeves when working around UV lights.

What Is The Best UV Light For Plants?
For the best results, use high-quality UV grow lights. Many full-spectrum LEDs emit the right amount of each type of UV light, mimicking natural sunlight.
At Nexsel, we offer a wide selection of UV Spectrum LED Grow Lights. Check spectrum selection guide for more information of UV percentages in Nexsel lights.
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