How to Use a Light Meter for Houseplants

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Today, I’m going to talk to you about how and why to use a light meter. Lighting is the key to healthy houseplants. Without sufficient lighting or the right lighting, houseplants won’t thrive. If you’ve seen my videos on lighting and other videos, you’ve probably heard me say that many times. If you want to make sure that your houseplants have enough light, the best way to do that is with a plant light meter.

A light meter, and here’s one right here, enables you to accurately measure the quantity of light in each room and around your plants. You may think that your eyes are pretty good at determining the amount of light in your home, but once you try a light meter, you’re probably going to be very surprised. You may find that your estimations are pretty far off, which can explain why you have ailing plants that aren’t doing so well because they’re lacking light or getting too much light.

I have videos on what it looks like when plants get too much light and what it looks like when plants don’t get enough light. I will link those videos below, as well as any other videos I mention in this video.

As mentioned, the right light is so critical, and these handy gadgets help you determine the kind of lighting you have in your home. Knowing the exact amount of light a room receives helps you make the right decisions in plant placement. While you could use a photographer’s light meter, they aren’t designed to be sensitive to the same light wavelengths as the human eye, which is not what plants see and absorb. So, it’s a good idea to use a plant intensity light meter like this one.

These gadgets measure the wavelengths used for photosynthesis and chlorophyll production, which is what your plants need to stay healthy. Light meters usually show foot candles, though they can also show lumens. I’ll talk about foot candles today because it’s a simple way to measure light. A foot candle is the amount of light a candle gives off in all directions one foot from the flame. The light intensity of a sunny summer day is approximately 10,000 foot candles.

Some meters show low, medium, or high light levels, while others show actual foot candle measurements like this one does. I’ll turn it on now to give you an idea. The top number shows temperature, and the bottom number shows foot candles. You can see that it’s going between 49 to 56 foot candles from the light around me. I prefer a meter that shows actual foot candle numbers rather than vague low, medium, or high levels.

This meter also has a button to change to lux, but I have it set to foot candles (FC). Below, I have lists of many houseplants and the foot candles they require, broken down into low light plants (50 to 100 foot candles), medium light plants (100 to 300 foot candles), and high light plants (300+ foot candles).

For tips on using a light meter, you’ll want to measure the light intensity at the leaf level. Right now, it’s showing about 30 foot candles, which is pretty low because my windows are closed and I have lighting for filming. It’s important to remember that lighting for plants is different from lighting for videos. As you get closer to a light source, the reading will go up, so placement is key.

If you’re using full-spectrum lighting, get the reading right at the top of the plant. I also have a video on plant placement under full-spectrum lighting, which I will link below. Make sure to check various times of day—morning, afternoon, and midday—for accurate readings. If you’re thinking about moving a plant, you can check the light levels in its new spot before moving it to ensure it’s suitable.

For example, this beautiful Coleus is a medium light plant that requires 100 to 300 foot candles. If I wanted to move it to my living room, I’d use the meter to make sure it gets the right light level. For low light plants, like this Peperomia, you need to be careful not to give them too much light, as they can easily burn. High light plants, like this Hoya, require 300+ foot candles to thrive. If you’re having trouble getting a plant to flower, like a Hoya, it might not be getting enough light. This is where a light meter becomes very useful for figuring out the issue.

I’ll link below to good light meters and plant care videos to help you find the perfect spot in your home for your plants. As mentioned, I also have lists of low, medium, and high light plants. Some low light plants include Arrowhead Vine, Cast Iron Plant, Chinese Evergreen, Dracaena, Peace Lily, and Pothos. Medium light plants include Coleus, African Violet, Croton, Goldfish Plant, and Grape Ivy. High light plants include Hoya, Zebra Plant, Citrus, and many fruiting plants like tomatoes.

Remember, the key to growing healthy plants indoors is using the right tools like a plant light meter. Make sure it’s for plants, not photography, and it will help you grow a lush, thriving indoor garden.

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<h3>Frequently Asked Questions about Using a Plant Light Meter</h3>

<h4>What is a plant light meter and why is it important?</h4>
<p>A plant light meter measures the quantity of light in your home and around your plants. It helps ensure that your houseplants receive the right amount of light to thrive.</p>

<h4>Can I use a photographer’s light meter for plants?</h4>
<p>No, a photographer’s light meter is not designed to measure the same light wavelengths that plants use for photosynthesis. It’s better to use a plant light meter designed specifically for this purpose.</p>

<h4>How do I measure light intensity for my houseplants?</h4>
<p>To measure light intensity, use the light meter at the leaf level of your plant. Check various times of the day to get accurate readings of how much light your plant is receiving.</p>

<h4>What are foot candles, and why are they used to measure light for plants?</h4>
<p>A foot candle is the amount of light a candle gives off in all directions one foot away. Light meters often use foot candles because they provide an accurate measure of the intensity of light needed for plants to thrive.</p>

<h4>What are the light requirements for different types of plants?</h4>
<p>Low light plants require 50-100 foot candles, medium light plants need 100-300 foot candles, and high light plants require 300+ foot candles. You can check your plant’s requirements using a light meter.</p>

<h4>How can I tell if my plant is getting too much or too little light?</h4>
<p>If a plant is not thriving, using a light meter will help you assess whether it’s getting too much or too little light. You can adjust the plant’s placement based on the light meter readings to meet its light requirements.</p>

<h4>Can I use a light meter with full-spectrum lighting?</h4>
<p>Yes, you can use a light meter with full-spectrum lighting by placing the meter at the top of your plant. Measure the intensity at different times of the day to ensure the plant is getting the proper light.</p>

<h4>What are some common low, medium, and high light houseplants?</h4>
<p>Low light plants include Arrowhead Vine, Cast Iron Plant, and Peace Lily. Medium light plants include Coleus, African Violet, and Goldfish Plant. High light plants include Hoya, Zebra Plant, and Citrus.</p>

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