When growing plants indoors, it is important that you find something that will serve as a substitute of the sun. That said, what’s really important is that your plants get enough light, whether it’s natural or artificial. However, do you really know how does the color of light affect plant growth?
There could be multiple answers to this question, but one of the most common answer you’ll hear would have something to do with photosynthesis.
You need to know that plants are named as autotrophs, and so this means that they can create their own food and energy. That’s what photosynthesis is all about.
Photosynthesis is the process that plants go through in order to produce their own energy or food.
This is probably something that you’ve already heard about back in school but never really bothered to care about so let me help refresh your memory to understand the effect of red, blue and white light on plant growth.
Adequate Lighting and Plant Growth
As mentioned, photosynthesis is the main reason why plants need light. For photosynthesis to take place, the plants will need carbon dioxide, water, and light. This also happens because the chlorophyll found on the leaves of the plants.
Chlorophyll is what help the plants absorb the energy from the light. The energy that the leaves get from the lights is what helps turn carbon dioxide and water into glucose, which then becomes the plants’ food and energy.
Focusing on the effect of light during photosynthesis, another thing that matters is the light intensity. You need to make sure that your plants are getting just the right intensity of light as it will determine the efficiency of the photosynthesis that takes place.
If your plants do not get the right intensity of light, they will only produce little amount of food and energy. This will significantly affect the growth of your plants.
Light is in fact so necessary that plants actually grow towards it. These plants are called phototropic. There are also the heliotropic plants, like the sunflower that turn its blossom towards the sun. Either way, these plants just show how they actually live for light.
Sunlight Vs. Artificial Light in Plant Growth
Obviously, there is quite a difference when it comes to using natural or artificial lights when it comes to growing plants. This is even a debate that could go on for ages, but the bottom line is that you can grow plants with both artificial and natural light.
Actually, when you’re growing plants indoors, there shouldn’t really be a debate when it comes to using artificial or natural lights.
Most indoor growers would easily resort to artificial lighting as it could be challenging to rely on the sun only.
The sun is something we can’t control, and the downside of this is that we can’t always expect the sun to be there when your plants need it.
The debate will then come to what kind of artificial light they should be using as there are quite a few choices that they can decide on.
What you should know is that when it comes to light, the spectrum is what’s important to ensure that your plants will actually grow.
Which color of the light spectrum are most important for plant growth?
Plants grow, that is a given. Have you ever thought about the light that makes the plant grow? The light spectrum that those plants use is completely different than what you think.
You think of the sun as yellow, it is much more than that. How do we know this?
A rainbow forms when sunlight enters droplets of water. When done at a specific angle the droplet separates the light into many different colors, and you see the entire visible light spectrum. Those visible colors being red, orange, yellow, green, blue, indigo, and violet.
Another good example is how when you try to reflect light with the use of a prism, like a diamond. You also get to see the different colors that light has.
What does this have to do with plants? LOTS!
With that established, sunlight provides a spectrum to help your plant grow. When it comes to using artificial lighting, what’s right is that you can control the spectrum that you give your plants during its growing process.
There are different colors that your plants can benefit from so we will talk about how each spectrum or color affects the growth of your plants.
how does yellow light affect plant growth?
According to NASA researchers, this spectrum doesn’t really have much effect on the growth of your plants. A lot actually debate on this, but some researchers actually found that plants exhibit less growth if they are only exposed to this color without the blue and red spectrums.
Each one of these colors has a different effect on plants.
- Violet – You want lots of this color if you are growing edible plants. Violet gives you better color, taste, and makes them smell better
- Blue – You will want to use more blue spectrum light if you want your plants to grow faster.
- Green – Plants use more of this color to create chlorophyll. That is the food they produce to survive.
- Yellow – This color is useful, but not as much as blue and red light
- Red – Use this color, depending on what you are growing, to create more leaves. Combined with blue, it will produce larger crops.
full spectrum white led grow light
You may think that this alone is crucial because you see sunlight as mainly white and a bit yellow, but the thing is that you see full spectrum white led grow light because of the combination of colors that light has. Specifically, you see the white color because of the spectrums red, blue, and green.
However, since this color has a red and blue spectrum, it’s safe to say that the color white plays an important role when It comes to your plant’s growth.
What Effect Does Green Light have on Plants?
The color of your plants is mainly because of chlorophyll, and this is why it also has something to do with this spectrum.
The green spectrum enhances the chlorophyll production of your plants. Experts use this as the pigment for proper plant viewing.
Plants actually still use green light for photosynthesis, but they absorb this spectrum less. That’s why our plants are colored green.
It’s also safe to say that without the green spectrum, there could be an adverse effect on your plant’s growth.
how does purple light affect plant growth?
This color is as effective as the blue light when it comes to helping your plants grow. It is said to enhance the color, taste, and smell of your plants.
With this said, the violet or purple light alone is not really ideal to use on its own as this is more of an enhancer. This color is excellent to use during the vegetative process.
Why Do Plants Grow Better in Blue Light?
The blue spectrum is widely used when growing plants indoors, just as the red spectrum. This is known to help speed up the growth of your plants and is also crucial when it comes to ensuring your plants’ growth.
In fact, this is necessary during the early cycle of your plants, as it helps with seeding and leaf growth.
This light spectrum also helps with the production of chlorophyll, which also makes it essential during photosynthesis.
This ensures the strength of your plants’ roots, stems, and leaves. Without this spectrum, your seeds won’t even raise from the ground, and your plants will become weak and yellow in color.
What Effect Does Red Light have on Plants?
This spectrum is best used during the flowering stage of your plants as this have a longer wavelength than the blue light.
This spectrum is indeed important to your plant’s growth but using only this light won’t really lead you somewhere good when it comes to growing plants.
The red light always has to be partnered with the blue spectrum to ensure that your crops will be healthier.
While you can already use this spectrum during the early stage of your plants’ growth, you’ll mainly see its efficacy during the latter part of the cycle, when your plants are on its flowering stage.
No matter what plant you are growing indoors, the most crucial colors needed are red and blue. Some sources say to have 10% blue and 90% red. Other say a 30% blue and 70% red is best. It will depend on what you want your plants to do. It will also depend on what plants they are. You can add other colors from the spectrum, using the information above, to add other growth characteristics.
Why is PAR Rating a Big Deal for Indoor Grow Light Systems?
The "PAR" or Photosynthetically Active Radiation is useful when it comes to knowing the amount of light that is available during photosynthesis.
Since we’ve already established that the different light spectrum or colors affect your plant’s growth, knowing PAR will help you determine the necessary wavelengths your plant needs to grow healthy.
What you must know is that when there’s no light, it means that the PAR is at zero. For growers, the measure of Par ranges from 400 to 700 nanometers, which also covers the different light spectrum we just mentioned.
During the vegetative stage, your PAR should be at 400-490 nanometers. You can get a PAR meter to quickly know the wavelengths that your grow lights have.
It will help you understand what spectrum you’re missing on or will need to ensure your plant’s growth.
How does light exposure affect plant growth?
When plants do not get exposed to light, photosynthesis won’t take place, and that only means that the plants won’t produce enough food and energy for them to be healthy or grow at all.
The needs of your plants when it comes to light varies, so make sure you check if your plants are considered to be in the low-light, medium-light, or high-light category.
For low-light plants, they only need at least 4 hours of exposure to light. Medium-light plants need at least 8 hours, and high-light plants need about 12 to 16 hours of light exposure.
It’s also crucial that you establish a routine when it comes to light exposure so that your plants won’t have a hard time adapting to photosynthesis and the opposite of it, which is respiration.
What Happens If Your Plants Do Not Receive Enough Light?
When plants do not get enough light, multiple things could happen and trust us, there’s nothing positive that could happen! Here are a few signs that could help you determine if your plants are not getting enough light:
- Yellow Spots – this is due to lack of chlorophyll since the plant is not getting enough light to produce more of this.
- Plant’s Growth – You’ll notice that your plants aren’t getting tall when it should be.
- Extended Internodes – This is the spacing between the leaves. If your plants do not get enough light, the spaces between the leaves of your plants will be bigger.
- Small Leaf size – Since the leaves are not producing energy and food, it won’t grow as it should.
- Leaning – Since your plants are struggling to get enough light, the tendency is it will look for what it needs, so you’ll notice that the plant itself will extend and lean towards the light. However, it will not seem like it’s growing healthily as it will look like it’s having a hard time leaning towards the light.
How does light intensity affect Plant growth?
This is an important aspect when it comes to using grow lights. You don’t want to fry your plants up during the time it is exposed to lights. The light intensity can be manipulated through distancing the light from your plants.
The distance of your grow lights will really depend on the type of grow lights you will use. Some growers go for metal hides, and HPS (High-Pressure Sodium) grow lights, while some use fluorescent or LED grow lights.
Metal Hides and HPS grow lights can create an intense heat during the time it is on, while LED grow lights doesn’t really produce much heat.
Generally, you can do the hand test to know if the heat that your grow lights are producing is becoming somewhat harmful than helpful.
The hand test is done by simply placing your hand under your grow lights, just above your plants, for about thirty seconds.
If you find the heat too much to bear with that duration, then it means that you should be putting more distance between your grow lights and your plants.
Always remember to have this checked to avoid mishaps. Your plants could wilt, dry up, weaken, or worse, die if you leave them exposed to the high heat produced by your grow lights.
does the color of light affect plant growth? conclusion
Now that you understand how does different color light effect affects the growth of your plants, it will be easier for you to have this considered as a crucial part of your setup.
The bottom line here is that lack of light can’t really make you a successful indoor grower, but what you need to know is that overexposure to light can also happen so make sure that you have your setup well-composed.
While there are different types of grow lights that you can use when setting up an indoor garden, always take note of the plants that you are trying to grow and their specific needs.
It’s also good to keep the growth stage or cycle in mind just so you can adjust the spectrum of your lighting to accommodate your plants’ needs.
Lindsey Hyland grew up in Arizona where she attended University of Arizona’s Controlled Environment Agriculture. She has supplemented her formal education by working on various organic farms, including spending a semester abroad in India.
Growing and/or raising just about anything gets her excited. She is especially passionate about environmental justice and low-tech, sustainable ways to better run small-scale farms and homesteads. Lindsey started Urban Organic Yield to discuss gardening tips and tactics.