Light Meter For Plants

If you're confused about which light meter is best for your plants, let us help. We picked here the best light meters for plants and explain how to use them.

Purchasing a light meter for plants can be game-changing.

If you plan to grow indoor plants using grow light, owning a light meter will help you a lot. You can also use light meters to measure the amount of light your outdoor plants receive from the sun.

A light meter can provide you with a lot of valuable information. It will help you increase the growth and yield of your indoor plants.

Light meters vary in type depending on what aspect of light they can measure.

The most common light meters used in gardening measure lux (or lumens). The other type of light meter measures PPFD.

The most relevant light measurements for plants are PPF and PPFD (Photosynthetic Photon Flux Density). They can assess the intensity of Photosynthetically Active Radiation (PAR), the range of light plants use.

On the other hand, lumens, lux, and foot candles can give us information about the overall intensity of light but not the quality.

A PAR meter, also known as quantum flux or PPFD meter, usually costs much more than a lux meter. But it provides more specific data about light.

It is important to note that you might not always need a PAR meter; a lux meter can sometimes be enough.

If you haven’t yet owned a light meter and are planning to buy one, then you are in luck.

We will be discussing in detail all about light meters in this article. We will also highlight the best light meter perfect for your indoor plants.

Let’s get started!

Table of ContentsShow

A Lux Meter Can Measure Overall Light Intensity

The source of all direct sunlight is one—the sun. So, the quality of sunlight is nearly always the same.

That means you don’t need to measure the PAR output of natural light. Instead, it would be best to focus on finding the intensity of sunlight your plants receive.

We can learn that by measuring lux or lumens instead of PPF or PPFD, a lux meter can get the job done in this case.

Without a doubt, the best lux meter to use for plants is Dr.meter 1330B.

If you have lux light concerns, consult your Dr.meter 1330B. Unlike many other lux meters, Dr.meter 1330B has an amazing design that makes it very flexible.

The light sensor connects to Dr.meter via an elastic coiled cable. You can stretch that cable to reach different spots around your plant.

Laboratories and photography studios use the lux meter as much as growing setups.

Dr.meter 1330B is very sensitive to bright light and can also measure intense lux (up to 200,000).

The device is a best seller on Amazon in the category of light meters and has many positive reviews.

Dr.Meter 1330B is very affordable. So, if you believe you need a lux light meter and want something affordable, the Dr.meter 1330B is your best choice.

How To Use A Lux Meter With Your Plants?

Using Light Meter For Plants

Using a light sensor is easy. In the case of Dr.meter 1330B, all you have to do is place the light sensor near or at the same level as the plant’s leaves.

Make sure the sensor is facing the light source. The light meter will then measure the lighting levels and obtain valuable readings.

Remember to measure light at different hours of the day. Also, measure in various locations around the house or the growing area.

How To Understand Lux Readings?

To use your measurements, you should first learn about your plant’s light requirements in terms of lux.

Keep in mind that direct sunlight measures about 110,000 lux on a sunny day outdoors. It only measures about 1100 lux on a cloudy day.

Considering that information, plants have different light requirements. It all depends on the climate in their original habitat.

To make it easier for you, gardeners have classified plants according to their light needs: low light or partial shade plants, medium light or partial sun plants, and high light or full sun plants.

Very low-light plants can thrive on about 1000 lux, while medium-light plants need about 35,000 lux.

High-light plants need at least 50,000-60,000 lux to thrive. Some full-sun plants need much more than that.

Roses are high-light plants

You can check any gardening encyclopedia to learn about the light needs of a plant. You can learn more about lux requirements for plants here!

Refer to the above information. Your lux readings allow you to decide where to locate your plants around the house. It will also help determine if your outdoor and indoor plants get the sunlight they need.

You may find that the light intensity around your house is not enough for your plants. In that case, you should invest in supplemental LED grow lights.

A PPFD Meter Can Measure The Intensity of Useful Light (PAR)

Using a light meter for plants growing under lights is a different story. And to be honest, it’s a bit more complicated too.

Testing artificial light is usually done to assess light intensity, quality, or both.

The quality of light varies significantly from one grow light to another. Some grow lights produce more PAR or different light frequencies than others.

So, even if a lamp emits 20,000 lux, that doesn’t mean you can grow plants under it.

You should know the amount of PAR a lamp puts out before attempting to grow any plant under it.

If you can get your grow light’s PPF or PPFD measurements from a credible source, you won’t need to measure them again. Therefore, you can only use a lux meter to measure the light intensity at the level of the leaves.

This measurement will help you decide whether to raise or lower the fixture. But, this approach isn’t the best.

If you want to pull the highest yield from your plants, you will benefit from having a PPFD meter.

The best PPFD meter on the market is Apogee MQ-500 PAR Meter. It is the most commonly used PAR meter by professional indoor gardeners.

Apogee manufactures several PPFD meters, but the MQ-500 works for all light sources, including LEDs.

The company advertises MQ-500 and other PPFD meters to scientists—so you can expect their devices to be highly accurate.

Apogee MQ-500 is very sensitive and responsive. You will be able to see the PPFD measurements in real-time as you move the meter around the growing area.

You can use the instrument in different growing environments. It is sturdy and waterproof.

Although the technology behind the device is advanced, Apogee MQ-500 is very easy to use.

One slight downside—the price. Apogee MQ-500 PAR Meter is high-priced. So, at first, you may hesitate to buy it.

But, this device will allow you to take indoor growing to the next level and maximize your yield. Getting the Apogee MQ-500 PAR meter is worth the investment if you really want your indoor plants to thrive.

Many indoor growers who use this device will tell you that having a PPFD meter is priceless. This is because it will give you more control over your plants’ growth in time.

How To Use A PPFD Meter With Your Plants?

Using a PPFD meter, you can take several PPFD measurements around the plant canopy.

You should cover all the growing areas with the PPFD meter. Then jot down the measurements in a chart, like the one shown below.


How To Understand PAR Readings?

The PPFD measurements will allow you to choose the plants you can grow under a light fixture.

If you turn on your grow light for 14 hours daily, the most light-demanding plants will need no more than 700 μmol/m²/s to flourish. Medium-light plants will thrive on 300 μmol/m²/s.

Constantly measure your PPFD values at different distances between the plants and the grow light. That way, you can decide when to raise your fixture as your plants grow taller.

The PPFD values also show the discrepancy in PAR between the center and the sides of the coverage area. These values will allow you to assess the uniformity of a grow light.

If the light is uniform and intense, you can grow a combination of full sun plants all over the growing area.

But PPFD values of your light level may vary significantly around its coverage area. You might have reduced yield in the plants growing at the sides.


Whether you are growing potted plants indoors or outdoors, all plants need light. And it doesn’t matter if it comes from the sun or indoors via grow lights.

Light measurement for plants is a brilliant way to optimize indoor growing. It can ensure your plants are getting the amount of light they need.

There are two ways to measure light: You can measure the intensity of light in terms of lux or its intensity and quality in terms of PPF and PPFD. So, to measure light, you need a lux or PPFD light meter.

Lux meters will measure the intensity of light in terms of lux. You can use them to take sunlight readings or when you want to estimate the light intensity of a grow lamp.

If you have lux light problems, count on Dr.meter for help. Dr.meter 1330B is currently the best lux meter on the market.

To check the quality of light, though, you must use a PPFD meter. And for that, the best PPFD meter is Apogee MQ-500 PAR Meter.

Apogee MQ-500 PAR Meter is a bit expensive. But it is beneficial for professional indoor gardeners.

It allows them to fully assess the artificial light quality and intensity. And if you want your indoor plants to thrive, investing in a PPFD light meter will be worth it.

Do you have a light meter as one of your tools for indoor gardening? What light meter do you use?

Share your thoughts and comments in the comments below!

Illustration Credits:
Gardening Vectors by Vecteezy
Light Meter Vectors by Vecteezy

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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.