Green Light for Plants: Why Is It Important?

Red and blue light are important for your plants, but other light frequencies can also have a great impact on growth.

Green light, for example, plays a significant role in plant development, but many growers overlook its importance.

green light for plants

In this article, we’ll discuss why you shouldn’t overlook the importance of green light for plants.

The Importance of Green Light for Plants

Study after study showed that green light is necessary for plant growth. Here are the main reasons why:

1. It Has a Positive Effect on Photosynthesis

Photosynthesis is driven by photosynthetically active radiation (PAR). On the spectrum, PAR ranges from 400 to 700 nm.

Green light is included in the PAR range, so it can drive photosynthesis, but not nearly as good as red or blue light.

However, today, we know that green light can somehow make photosynthesis in plants more productive.

A study done on lettuce found that plants grown under red, blue and green light had higher photosynthetic rates than ones grown under red and blue light only.

lettuce under light

The study also showed that green light increases the expression of genes involved in photosynthesis and reduces the negative effects of continuous and prolonged light exposure.

Plants growing indoors receive longer hours of light than those growing outdoors. Prolonged exposure of light can harm the productivity of your plants.

Since green light can decrease the harmful effects of light stress on photosynthesis, it’s very useful for indoor plants.

Several other studies, including a study done on sunflower leaves, showed that green light plays a key role in enhancing photosynthesis.

2. It Increases Plant Mass and Height

Increased photosynthetic activity leads to an increase plant in mass and height. And separate studies show that green light increases plant growth.

A study done on flowering plants showed that exposure to green light can increase the growth rate of seedlings and make them taller. More importantly, it found that green light can increase the yield of plants.

Another study done on tomato plants revealed that adding green light to the spectrum can increase the yield of tomatoes, their stem length, their leaf area, and their mass.

Those studies, although not conclusive, prove that green light has a significant impact on the yield.

tomatoes under light

3. It Has Great Leaf Penetration Ability

The ability of light to penetrate the top leaves and reach the lower leaves depends on its quality.

Indoor growers pay a lot of attention to light penetration because it can increase the yield of their plants.

If light cannot reach the lower leaves of your plants, photosynthesis will decrease.

Over the years, grow light manufacturers tried to come up with solutions to increase the penetration of artificial light. Some of these solutions involved changing the designs of grow lights.

But manufacturers discovered an easier way to increase light penetration by adjusting the spectrum.

Many studies show that green light can penetrate the leaves far better than red or blue light. This feature makes green light valuable for indoor growers.

Adding green light to the spectrum of grow lamps will increase the photosynthesis in the lower leaves and improve yield.

green light leaves

4. It Enhances Visibility

Every professional grower knows that it’s crucial to monitor your plants during their growth.

By checking up on your plants regularly, you can spot and solve serious problems before they affect the growth.

Many LEDs found on the market today emit a dazzling light that makes it harder for the grower to see their indoor plants clearly. Those lamps mostly emit red and blue light, producing a final purple color that reduces visibility.

Although it might sound like a minor problem, it’s actually very serious. Most indoor gardeners avoid buying those “blurple” lights for that reason.

Modern LEDs have resolved that problem by adding good quantities of green light to the spectrums of their lamps.

Green light can improve visibility, making it much easier for the grower to observe their plants.

So, above its ability to improve growth and penetration, green light can help the grower view things better.

visibility of plants under green light

How Much of Green Light Do Your Plants Need?

Green light is useful for plants, but in what quantities?

Plants need most of their light as red and blue, so they need green light in lower amounts.

In fact, science tells us that too much green light can have negative effects on plant growth.

The Negative Effects of Too Much Green Light on Plants

Green light can counter the effect of blue light on plants.

Many important processes in plants are triggered by blue light, and studies show that green light can inhibit them.

So, in large quantities, green light can decrease photosynthesis and reduce the yield of plants.

Green light might have a negative effect on THC levels in cannabis unless it’s combined with good quantities of blue and red light.

Green light can also trigger the symptoms of shade avoidance syndrome (SAS). SAS is associated with decreased yield in plants.

As an indoor gardener, what can you do to benefit from green light but avoid its negative effects?

The Play-it-Safe Approach: Use Green Light Moderately

Many grow lamps today incorporate green light into their spectrum, but in very moderate amounts.

Here’s the spectrum of one famous series of grow lights manufactured by Black Dog:

black dog led spectrum rich in green light

It has a moderate quantity of green light compared to that of red and blue. This spectrum is highly optimized for plants, especially cannabis.

Always choose a grow light that emits enough quantities of red and blue light to curb the negative effects of green light.

But never choose a grow light that doesn’t emit green light.

Conclusion: Green Light is important for Plants but in Moderate Quantities

Green light can improve the rate of photosynthesis, increase plant mass and height, and enhance visibility. It also has a great leaf penetration ability.

But too much of green light can have a negative effect on your plants.

So, to play it safe, choose grow lamps that put out moderate amounts of green light and significant quantities of red and blue light.

Enjoy growing your plants and don’t forget to share your thoughts in the comments below!

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I'm Jad, a biologist, blogger, and experienced indoor gardener. I am knowledgeable in plant biology, particularly in plant cultivation and propagation. I founded HerbsWithin.com in 2019 to share my knowledge in indoor gardening with passionate home growers.

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