Are Grow Lights UV?

If you've been comparing grow lights online, there's a decent chance you've run into someone claiming they're basically UV lamps in disguise. Or maybe you spotted “UV” somewhere in a spec sheet or a forum thread and started wondering what that actually means for your plants, your pets, or you.

It's a fair question, and a common one. Here's the direct answer, along with the light science behind it.

TL;DR

• Most grow lights, including Soltech's, don't emit any significant amounts UV light.

• Grow lights are built to produce PAR (400 to 700 nanometers), the visible light range plants use for photosynthesis, not UV.

• Plants don't need UV light for basic growth either, so this isn't something to worry about.

• Some commercial and cannabis cultivation setups intentionally add a small amount of UV for specialized purposes. That's a different category of light than what's used to grow houseplants at home.

What Wavelengths Count as UV Light?

Light is a form of energy that travels in waves, and it covers a much wider range than what our eyes can pick up. Scientists organize that full range into what's called the electromagnetic spectrum, which stretches from long, low energy waves like radio waves, all the way to short, high energy waves like gamma rays. Visible light, the rainbow we can actually see, sits right in the middle of that range.

Ultraviolet light sits just past the violet end of what we can see, in the range of roughly 100 to 400 nanometers. It's invisible to us, which is a big part of why it causes so much confusion. You can't look at a light fixture and tell whether UV is part of what it's putting out.

UV breaks down into three bands based on wavelength:

• UVA: 315 to 400 nanometers
• UVB: 280 to 315 nanometers
• UVC: 100 to 280 nanometers

According to the U.S. Environmental Protection Agency, UVA and UVB are the two types that reach the earth's surface from the sun, and they're the ones associated with things like sunburn and skin aging over time with enough exposure. UVC is mostly filtered out by the atmosphere and shows up almost entirely through artificial sources.

That covers what UV actually is. Now let's look at where grow lights land in this range.

What Wavelengths Do Grow Lights Actually Produce?

Grow lights aren't designed around the full spectrum of sunlight. They're designed around one specific slice of it, the wavelengths plants actually use to photosynthesize.

That slice is called PAR, short for photosynthetically active radiation, and it spans roughly 400 to 700 nanometers, the same range we see as visible light, moving from blue through green, yellow, and red. According to the Iowa State University Extension, this range drives a plant's food production, along with things like leaf color, stem length, and flowering.

UV Light is approximately 100-400 nanometers. Photosynthetically Active Radiation (PAR) is about 400 to 700 nanometers.

Look back at where PAR sits relative to UV. It's right next to it on the spectrum, but it's a separate range entirely. A grow light engineered to deliver PAR is engineered to stay in that 400 to 700 nanometer window, not to reach down into UV territory.

If you want a closer look at how this compares with real sunlight, we broke it down in Grow Lights vs. Natural Sunlight: Do Plants Actually Know the Difference.

Do Grow Lights Emit UV Light?

Here's the direct answer: no, not typically, and not with Soltech grow lights specifically.

Home grow lights, including the Soltech grow lights, are built to concentrate their output in that visible PAR range. UV isn't part of the design, because it isn't part of what a houseplant needs in order to photosynthesize.

UV does show up in a different category of lighting. Certain commercial and cannabis cultivation setups intentionally add a small amount of UV-A to their light recipe, aiming for specific effects like pigment development or resin production in particular crops. That's a deliberate engineering choice made for a specialized use case, not something you'll find in a light built for a fiddle leaf fig in the corner of your living room.

If you're curious about the safety of Soltech lights for people and pets, we cover that in Are Soltech Grow Lights Safe for Humans and Pets?.

Do Plants Need UV Light to Grow?

No, not for the basics. Photosynthesis runs on that 400 to 700 nanometer PAR range. A plant growing under a quality grow light indoors has everything it needs to convert light into energy, with no UV involved.

UV's role in nature is smaller and more specific than people often assume. In a collection of studies published in Frontiers in Plant Science, researchers find that UV light mostly acts as an environmental signal that triggers plants to adapt to stressors, prompting plants to build up their own "sunscreen" and protective antioxidants. In the case of indoor farming, growers can also strategically use targeted UV exposure to boost crop growth and nutritional value. Neither of these cases are important when we're talking about keeping your houseplants healthy and thriving indoors.

In other words, your pothos isn't missing out on anything by growing under a UV free light. The visible spectrum is doing all the actual work.

Is UV Something to Worry About With Grow Lights?

Since this question comes up a lot, it's worth answering directly: no, not with the kind of grow light you'd use for houseplants at home.

The EPA notes that UV exposure at high, sustained levels is associated with effects on skin and eyes over time. That's true of extended sun exposure, and it's true of products built specifically to emit a lot of UV, like tanning beds or the UV-B lamps used in reptile terrariums.

A standard home grow light isn't in that category. Since it isn't emitting meaningful UV to begin with, there isn't a comparable exposure to think about. It's simply a different kind of product, built to do a different job.

If you want the specific rundown on this exact question, we have a whole post on it: Can You Tan Under Soltech Grow Lights?.

How Do Grow Lights Compare to Sunlight and UV Lamps?

Here's a simple way to see how different light sources stack up when it comes to UV. These are general categories rather than specific product measurements, since UV output varies by design and manufacturer.