What Color Light is Best for Plant Growth

Blue is the best color for growing a plant. But it’s more complicated than that. Sunlight is best for plants’ growth, but it’s yellow.

Now, here is the deal.

Sunlight contains all the colors, and so when sunlight lands on a plant, it absorbs the color it needs and reflects the other color.

In other words, plants do best under the blue color when combined with red. In Fact, the color red should be more than the blue color. The color red on its own is not useful.

In this article, you will learn all you need to know about colors and plant growth, An example of how and in what ratio do the plants need red and blue. Apart from that, you will learn the function of other colors in plant growth.

What Happens to Plants When You Plant Them Under Different Color Light?

As seen above, the red color doesn’t work on its own, but blue on the other side works on its own. How much light you use on the plants depends on what plant and at what stage is the plant.

Red and blue should be combined in the ratio of 5:1 to get the best results. Below are colors of the visible color spectrum and what effect they have on the plants.

Spectrum Visible Light


When violet reflects on the plant, it has little effect on the plant. On the other side, when combined with red and blue, it brings about the best results. When violet is added to red and blue and reflected on the plant, it enhances the plant’s color, taste, and smell.


UV light is as harmful to plants as it is to humans. But it also has some advantages in some plants. For example, when UV light reflects on a cannabis plant, the plant creates a resin that protects the plant from harmful rays. Due to this, the buds of the plant become more potent.


The chlorophyll absorbs the plant’s blue color, which helps convert into energy in the photosynthesis process. This makes it an essential color in plant growth. When it works on its own, it is not as effective as it works together with red.


Plants are green in color because chlorophyll doesn’t absorb green light like it absorbs blue and red. Instead, it reflects the color, and that’s why plants are green. It’s easy to assume that plants don’t need and use the color green on photosynthesis activities from this concept.

Thus, plants seem to be green as the chlorophyll in the plant absorbs the red and blue color and reflects the green making the plant look green.

Green is not useless in the plant growth process. Apart from chlorophyll, other photoreceptors help in the photosynthesis process and absorb the green color. If your plant doesn’t get any green color, it will not get to its full potential.

The green color penetrates more than the other colors deeper in the plant to reach the photoreceptors. This is proof the green color is as important as other colors as it can be seen in the action spectrum showing the photosynthesis process.


Yellow is among the most visible spectrums in the sunlight. When it lands on the plant, it is the least useful color on the plants, but some of it is still used. When the light is pure yellow, it is of no help to the plant. Ensure the light you provide to your plants has less yellow as the plant needs little of it.

If the plant is getting light from sunlight, there is no effect as the light is free. But if you are creating light for your plant, there is no point in getting much yellow as only a small amount will be used in the process.


The orange color works the same as the red. In the absence of red, orange will take its place but will not be as effective as darker red. So if you provide the light for your plant, go for the darker version of red because it works better.


As seen above, red is among the most used colors in the growth process. But when red is used alone, it is useless. You need to combine it with the blue color and use the right ratio.

In Fact, during the flowering process, the red color is needed more in the red-blue combination. The red light helps make leaves stronger in the vegging process and the fruiting stage and comes up with the best bloom production in the flowering stage. Red light helps in a healthy plant and leads to higher quality and quantity in the yields.

Far Red

The far-red light is not absorbed much by the plants, but it has a vital role in the whole plant growth process. A ratio of red and deep red helps signify the plant to start the germination process, and apart from that, it helps regulate the flowering period of a plant.

What Effect Does The Red And Blue Light Have on a Plant’s Growth Process?

Sunlight is seen to be white, but it contains all the colors in the rainbow. Sunlight has three primary colors; red, blue, and green. As seen above, the green color is reflected by the plants on people’s eyes, which makes plants seem green.

The blue and the red color, on the other hand, are absorbed to help in the process. A bit of the green color is also absorbed and helps in the photosynthesis process.

The blue color is used in the chlorophyll process, which helps produce the energy used in plant growth. Plants that get enough blue color have strong and healthy stems and leaves.

Red, on the other side, is responsible for the flower-making process and production of fruits. It also helps in the early germination process by developing roots and the development of the bulb.

The Red Light or The Blue Light?

When the plant receives light from direct sunlight, it gets all the color it needs from the sunlight. But when the plant is indoors, it’s your role to provide the right light to help in the process.

When the plants are indoors, even those next to the window don’t get enough color spectrum. When you notice your plant getting leggy and losing the green color, it is a sign it is not getting enough of the blue color light.

When the plant is not flowering or blooming on time, it is a sign the plant is not getting enough of the red color light.

To get a blue light supplement, use the fluorescent lamp to provide the blue light to the plant. On the other hand, the incandescent bulb is perfect for the red color, but the bulb produces too much heat to affect the plant. So, in this case, a broad spectrum fluorescent lamp will supplement the red light.

Pollution could be the other reason your plant isn’t getting enough light as it is blocking the needed light. If you notice the unhealthy plant is next to a dirty window, the solution could be as simple as cleaning the window to let all the light in.

Best Types of Bulbs For Plant Growth and Development

T5 and T8 led bulbs are the most common grow bulbs. The bulbs have around 6500 kelvin, which is the color and temperature of sunlight, making them perfect for plant growth.

Most people opt for the blue bulb to provide the plants with the blue color, which helps in the energy production process that helps in strengthening the stem and the leaves.

But a 6500-kelvin bulb will provide the blue color, which helps in the vegetation process. Bulbs with 2700 kelvin help in the flowering and fruiting stage of the plant. This is because bulbs with 2700 kelvin contain a warm color that is produced during sunrise hours. This color is orange and red.

Instead of buying a blue and red bulb, get a fixture with a four bulb holder and alternate the 2700 kelvin and the 6500 kelvin to get the best results.

Conclusion on Which light helps plants grow faster?

A plant needs all the colors in the spectrum to get the best results. But there are those colors that are more important than the others. In this case, the red and the blue color and especially when both are combined.

When the plants are outdoors no need to worry as the sunlight will provide all the needed color, but for an indoor plant, you need to ensure you provide the light to ensure your plant remains strong and healthy.