LED Grow Light Wattage

We see wattage in grow light labels, but what is it really? In this guide, we'll explain everything about grow light wattage and the accurate way to use it.

There’s no doubt that the wattage of an LED grow light says a lot about its performance.

That said, watt is a measurement that is misused by indoor gardeners and LED grow light manufacturers. The reason behind that is the lack of information.

Below you’ll find all the information you need to know about LED grow light wattage.

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What Is The Wattage Of A Grow Light?

LED lamp for artificial lighting of indoor plants in short daylight conditions lies on pots with capsicum seedlings

Simply put, the wattage of a grow light is how many watts it consumes.

Watt measures electric power or energy. So, we can also describe wattage as the quantity of energy that a device consumes.

All LED grow light manufacturers provide the wattages of their devices.

But here’s a problem: they might also use this measurement to mislead you.

Before we discuss that, let’s talk about the correct usage of wattage when it comes to the assessment of LED grow lights.

LED Grow Light Wattage

Unlike fluorescent or HID lamps, different LED lamps might have the same wattage but emit different amounts of light.

All 1000-watt HID lamps have almost the same light intensity. 1000-watt LED lamps, on the other hand, have different light intensities.

There are several reasons behind that inconsistency.

First, different types of diodes are used to make LED lights, and some are more efficient than others.

LED Light Diodes

Second, some LED grow lights use cooling fans, and that can also contribute to the power consumption of those devices.

Finally, the way each LED light is designed can also affect its efficiency.

The above factors generally don’t affect other types of grow lights, and for this reason, they have more consistent measurements.

Since LED lights vary from each other, studying their wattages is very important.

The Accurate Usage Of Wattage

Rule number one is to avoid using wattage only to measure how powerful a grow light is.

Wattage is a measurement of electric power and not of light intensity.

You can use wattage to learn about the power consumption of a grow light. Accordingly, you can know the energy cost of the device.

For instance, if you’re running a 200-watt grow light for 14 hours each day, it will cost you around $120 per year in energy consumption (in the US).

That said, you can’t know how powerful a grow light is just by looking at its wattage.

Take a look at the following two grow lights, which one do they think has a higher light intensity?

LED Grow Lights Wattage Specs

The second grow light has a higher wattage than the first, so you may think it’s more intense.

But, in reality, the first one emits more light, even though it has a lower wattage.

That brings me to the next point I want to discuss: the efficiency of a grow light.

The efficiency of a lamp is the amount of light it emits for every watt of power it consumes. Some LEDs are more efficient than others, so you can’t assess the intensity of a grow light just by checking its wattage.

The most common efficiency measurement for grow lights is PPF efficacy.

PPF is the quantity of useful (photosynthetically active) light that a lamp emits per second (You measure PPF using a light meter). So PPF efficacy rate is the quantity of useful light that a lamp emits for every watt it consumes.

Grow lights with PPF efficacy rates above 1 μmol/J are efficient.

However, most LED grow lights nowadays have PPF efficacy rates above 2 μmol/J.

HLG Quantum Boards, for example, have a very high PPF efficacy of 2.5 μmol/J.

 HLG 100 V2 Quantum Board

To save money on your energy bill and to grow plants sustainably, you need to choose grow lights with high PPF efficacy.

Wattage As A Misleading Label

Unfortunately, there’s a trend among LED grow light manufacturers to use misleading watt measurements for advertisement purposes.

If you go on Amazon, you’ll see many grow lights labeled as 600W, 1000W, 2000W, etc.

Amazon Grow Light Labels

Most often, those labels don’t represent the actual wattage of the device. So, what do they stand for?

Well, they represent the wattage of the HID lamp that emits the same light intensity as the LED light.

Yes, I know, it’s very confusing. But why do LED grow light manufacturers use those labels?

HID lamps are very popular among indoor gardeners. You can sell an LED grow light faster if you can show that it’s way more efficient than HID lamps.

Those labels are there for that purpose, but they can mislead some growers.

The lesson here is that you should always check the actual wattage of a grow light on its description page.

Here’s an example:

Amazon Grow Light Wattage Example

As you can see, that light is labeled 2000W, but its actual wattage is around 390W.

Enjoy growing your plants indoors under lights and don’t forget to share your thoughts below!

Also, don’t hesitate to contact us if you have any additional questions.

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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.