Do LED Grow Lights Emit UV?

Grow lights produce specific wavelengths of light to help plants grow. There are blue wavelengths for vegging, red wavelengths for flowering, and a full rainbow of colors in between to help photosynthesis to occur in plants.

One light wavelength that has contested in the growing world is ultraviolet light (UV). UV light can be beneficial for your indoor garden, but only when you understand how to use them.

Do LED Grow Lights Emit UV

What is Ultraviolet (UV) light?

Ultraviolet light is a light wavelength that is invisible to the naked eye and lies between 10 nanometers to 400 nanometers on the light spectrum. There are four main types of UV light radiations, but only two are suitable in the indoor garden.

UV-A light Radiation (between 320 to 400 nanometers): UV-A light is used in many products, such as grow lights and lamps. Most birds and humans can perceive this light.
UV-B light Radiation (between 290 to 320 nanometers): UV-B light is not safe for humans, though most of it is absorbed by oxygen before it reaches the earth’s surface.

Some grow lights such as HID ballast and T5 naturally emit UV-A light through chemical exchange. While on the other hand, LEDs can be specially designed with UV-B bulbs or diodes to give them UV light radiations.

Effect of UV-A and UV-B on Plants

Using grow lights with UVs gives high-quality yields, richer scents and flavors, rich colors, and better adaptability to plants. Here is how a UV wavelength can affect your plants:

Rapid Photosynthesis

UV light has been shown to facilitate speed up the photosynthesis process leading to increased plant growth. UV-A light can increase photosynthesis by 12%, leading to increased leaf size, dry weight, and growth capacity.

If you want to get a bigger harvest from your plants, providing them with a full spectrum of light with UV light can help.

Increased Resin Production

Ultraviolet light helps crops produce resin, which increases terpenes and flavonoids in your plants. Terpenes are responsible for giving plants their smell and taste, while flavonoids give plants their rich, vivid colors.

When a UV wavelength hits a plant, the plant reacts by producing an organic compound known as resin. Resin is a protective compound that prevents the plant from losing water or being harmed by diseases, insects, or factors threatening their health, such as fungi.


When a UV light is too strong or placed too close to your plants, it can damage them. Exposure to much UV can lead to bleaching of your plants. Bleaching occurs when a plant’s cell is submitted to much light leading to damages or discoloring, while overexposure to a UV wavelength worsens things. Bleaching hiders leaves from absorbing light, which can lead to stunted growth and reduced yield.

Furthermore, overexposure to UVs can cause severe damages to terpenes and flavonoids. While leaves may not get affected, buds and fruits can lose flavor and aroma when exposed to too much ultraviolet light.

Does adding UV light to your grow improve potency? Is UV light good for plants?

Factors to Consider Before Using LEDs UV Lights

Whether you are using UVs light for a big, commercial operation or for small, private use, there are various factors you require to consider before using grow lights to add a UV wavelength to your indoor garden. Here are some of the factors:

Plants’ Specific Requirements

While not every plant produces resin, not all resin is useful. If you want to use UVs, first ensure your plants can benefit from them. And if they can, you will also need to consider the height and UVs power around your plants to produce resin safely.

Space and Height Limitations

You will need to hang UV lights at the same height as other lights. Placing UVs too close to your plants leads to bleaching, so ensure you have space to hang at a safe distance.

Safety Precautions

Long exposure to UV radiation without any protection can be dangerous to both plants and humans. You will need to limit the exposure time and ultraviolet light intensity for your plants as they can burn or bleach from these intense wavelengths. If you are spending most of the time exposed to ultraviolet light, make sure you wear protective glasses and long sleeves to prevent eyes and skin damages.


You will need to consider costs when deciding whether or not to use UV light in your indoor garden.

LED grow lights take time to incorporate UVs into their setups, making LEDs with an ultraviolet wavelength a bit expensive than other lights.
UV-T5s are the cheaper option and are ideal when you are already using T5, or HIDs grow lights.

How to Use UVs in Your Indoor Grow Garden

All the three major types of grow light sources on the market, HPS ballast, LED lighting, and T5 bulbs, can utilize UVs in one way or the other. While T5 and HID grow lights produce UV light naturally, LEDs don’t. However, each can add a UV wavelength for increased growth and wavelength.

LED Grow Lights

Although most LEDs will give you all the light wavelength your plants require for optimal growth, some LEDs are built with unique UV diodes that generate UV-B wavelengths. Advanced spectrum LED Grow Lights, for instance, provide these types of diodes, and they can give your plants an energy boost by turning on your grow light. An added advantage is that with these lights, the UV cost is not added into the light price; hence there is no extra cost outside the entire cost.

HPS and HID Grow Lights

The light emitted when HPS or HID lamps turn on naturally has ultraviolet light. However, if you want to supplement UV-B lamps or UV T5, you can use fluorescent lights to offer your plant an extra flavor boost. For instance, a Power VEG T5 54W Fluorescent Bulb can give your plants a suitable UV light dose. When using T5s in your indoor garden, hang them at the same height as your HID bulbs.

T5 Grow Lights

T5 grow lights depend on a chemical reaction activated by an electrical current. The reaction emits a lot of UV light, though most of it is blocked by the bulb’s phosphor. However, these lights can still produce an ultraviolet wavelength.


Natural sunlight is not truly an option for indoor gardens. That is why artificial lights are key for gardeners trying to grow their plants indoors. While most indoor grow light types produce little to no UV light, many horticultural grow bulbs are built with a unique light spectrum to give your plants the UV wavelength they need for optimal growth.

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