Best UV Grow Lights

If you're not sure which UV grow light is best for your plants, let us help. We did our research and rounded up the best UV grow lights for you.

This point may seem illogical to some growers. Harmful radiation, such as UV light, can positively affect your plants.

But nature works in weird ways.

UV light can help you increase your growth’s yield and quality. So, adding a UV lamp to your lighting system can be extremely useful.

This guide will show you the best three UV grow lights for indoor plants.

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Plants And UV light

Before we show you our list of the best UV grow lights, there are a few things you should know about UV light and plants.

Feel free to skip this section and scroll down to view our UV grow lights recommendations.

Why Is UV Light Useful For Your Plants?

Growing seedlings under special artificial LED lamps with a spectrum favorable for plants without sunlight

UV light is very energetic, so it can cause damage to living tissues.

Around 3% of sunlight is UV light. So, most plants are exposed to UV radiation in their natural habitats.

Plants have a natural mechanism to shield themselves from the harmful effects of UV lights.

They will activate specific processes, producing certain molecules. These molecules have protective functions, such as repairing damage or absorbing UV light.

The molecules are beneficial. They improve the quality and yield of the plants for indoor plant growers.

UV light is a range of wavelengths stretching between 100 to 400 nm. This range divides into smaller wavelength ranges (UVA, UVB, and UVC). UVA (315-400 nm) and UVB (280-315 nm) are mainly used in indoor gardening.

There’s a lot of debate about whether UVA or UVB is better for plants.


Growing seedlings indoors under a full spectrum led growing ligh

With a shorter wavelength, UVB light holds more energy than UVA light. Because of that, some growers believe it’s more beneficial. 

The effect of UVB light on plants has been well demonstrated in studies.

One study done on cannabis showed interesting results. Treating the plant with UVB light resulted in around 30% increase in THC content.

Another study revealed that UVB could make plants more resistant to pests and diseases.

In some species (in small quantities), UVB light can boost photosynthetic activity.

Other studies show that UVA light has similar effects on plants.

For example, UVA light can boost the levels of nutrients and volatiles in different plant species.

The famous grow light brand, Black Dog, did some experiments. They showed that UVA light can also increase THC in plants.

Like UVB light, UVA light can also boost photosynthesis and increase yield.

Plants under LED light Image

So, since UVA and UVB have similar benefits, why choose one instead of the other?

It’s true that UVB light can be slightly more beneficial. But it can also have detrimental effects on plants and people.

That’s why today, many UV-emitting grow lights put out UVA light instead of UVB light.

Mistakes made while using UVA light can be less dangerous than ones done using UVB. So, growers, especially beginners, can handle UVA light better than UVB light.

It’s up to you to decide whether you want to use UVA or UVB light for your plants. In all cases, you should know how to use the light correctly.

Important Guidelines To Follow When Using UV Grow Lights

  1. UV light is harmful to humans—it can cause skin damage and cancers. You should use UV lights in an enclosed growing space. And be sure to wear protective material while working around or under them.
  2. Exposing your plants to UV light for extended periods can harm them. For this reason, you must keep it on for only a few hours a day. Stick to the manufacturer’s recommendations to know how long you should keep the light on each day.
  3. Keep enough distance between your plants and the light to avoid damaging them.
  4. Don’t use just any UV light for your plants. Some UV lights can be very intense and destroy your growth.

Best UV Grow Lights For Plants 

Here are three superior UV grow lights that will improve your growth:

HLG is a famous brand of grow lights that manufactures first-class products.

Their HLG 30 UVA supplement is one of the best UV grow lights on the market.

The light is a 24-inch-long LED bar containing 365nm and 385nm diodes (in the range of UVA light). HLG 30 UVA supplement can cover a 4’ x 4’ (1.2m x 1.2m) to 5’ x 5’ (1.5m x 1.5m) area.

The device only draws around 30 watts of power, so it won’t cost you a lot of energy.

It’s also waterproof, so it’s great for humid growing environments.

The grow light is very affordable, considering UV lights are usually expensive.

Remember, this is UVA light. You still must take the necessary precautions. Follow the manufacturer’s guidelines while using HLG 30 UVA supplement.

California Lightworks is the only manufacturer with integrated UVB light in its full-spectrum grow lights.

And the brand’s SolarSystem UVB is undoubtedly the best UVB light on the market.

California Lightworks SolarSystem UVB is a T5 fluorescent lamp, not an LED grow light.

The light draws around 24 watts and has a power output of about 320 μW/cm² at 24 inches. For reference, UVB light measures around 200 to 280 μW/cm² on a sunny day.

California Lightworks SolarSystem UVB can cover a 4’ x 4’ (1.2m x 1.2m) growing area.

The light has a unique design allowing you to control up to ten units using a single switch or timer.

The recommended distance between the plants and this light is 24 to 36 inches.

This light is also pretty affordable.

Caution: Don’t work around this light without wearing protective equipment. Do not look directly into the light.

TotalGrow UVA bar is another excellent UVA light for plants.

The UVA grow light is monochromatic with a spectrum of 385 nm (high UVA).

TotalGrow UVA bar has a UVA output of around 40 µmol/s, and it can cover a 2’ x 4’ (0.6m x 1.2m) growing space. It draws around 30 watts, so it has an efficiency rate of about 1.3 μmol/J.

The minimum recommended hanging height for this light is 24 inches.

TotalGrow UVA is waterproof and has a daisy chain feature. It allows you to connect up to 24 to 48 units (depending on the voltage).

The light has a 30,000 lifespan and comes with a three-year warranty.

The price of this light is comparable to that of one HLG 30 UVA Supplement.

Final Words

UV lights can help you improve your growth and yield. But you need to know how to use them properly, or you could damage your plants.

Always follow the recommendations of the manufacturer. Most importantly, do your own research before using UV grow lights.

You can also test your UV lights with different plants before using them with your main crop.

And finally, we cannot overemphasize the importance of taking the necessary precautions while working around these lights. Happy growing!

Please share your thoughts in the comments below, and don’t hesitate to contact us if you need more help!

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Jad Daou

Jad has always been passionate about growing plants. When he finished high school, he majored in biology, which makes him very knowledgeable about agriculture.