How Do Different Colors of Light Affect Plant Growth?


The basic requirements for growing plants may seem fairly straightforward. To cultivate them, you will need soil, water, light, oxygen, the right temperature, and the mineral nutrients they need to grow. But the tricky part would be dealing with the details which are far from simple that what many people might imagine, especially concerning light.

A lot of plants require large amounts of sunlight to grow. Cannabis is no exception. It needs light to facilitate the growth process. And the required amount of light varies throughout the different stages of its growth. For this reason, growers must pay extra attention to how much light the plants are receiving from planting until harvest time. But that is just one of the factors to consider when it comes to lighting. Growers also have to consider the different colors of light and how they affect plant growth. So what are these different colors and how are they important in the cultivation of cannabis?

The Multiple Colors of Light

While visible light is often perceived as white, natural light consists of multiple colors. It is only through refraction of light that the many wavelengths of light are reflected to show different colors. Imagine light passing through a glass prism and creating a rainbow of colors. And each color may play a unique role in the growth process of plants. Here is a look at some of the color spectrum of light, their wavelength range in nanometers (nm), and how each can be beneficial in the various stages of cultivating cannabis. More importantly, they can be helpful in determining which type of grow lights to choose to cultivate cannabis indoors.

Wavelength range: 10-400 nm
Effect on plants: Studies have shown that prolonged exposures to ultraviolet (UV) rays from sunlight can do a lot of harm to humans. And the same applies to plants. Minimizing exposure to UV light protects plants from the unhealthy and potentially damaging effects of excessive amounts of UV light.

Wavelength range: 380-450 nm
Effect on plants: Violet light sits in the middle of blue and ultraviolet. Exposure to just the right amount of violet light could help improve a plant’s taste and color among others.

Wavelength range: 450-495 nm
Effect on plants: Blue light is one of the most important in the spectrum of color when it comes to plant growth and development. If you are trying to grown cannabis indoors, you will need blue light during the vegetative stage to enhance the plants’ growth. You might also want to pay attention to any leaf discoloration or when the plants appear to be growing tall and weak as this may be a sign that they need blue light to support their growth.

Wavelength range: 495–570 nm
Effect on plants: Green light may not play a huge role in photosynthesis compared with blue and red, but it can still have a positive effect on plants. A study shows that a 50-50 combination of green and red tend to grow taller than those cultivated in at least a quarter of blue light.

cannabisWavelength range: 570–590 nm
Effect on plants: Yellow light does not have much effect on photosynthesis. Plants do not absorb it and exposure to it as opposed other more beneficial colors can prevent or slow down the growth of plants.

Wavelength range: 620–750 nm
Effect on plants: While red light, on its own, may have limited ability to promote plant growth, it can have beneficial effects when combined with blue light in certain stages of growth. In growing cannabis, red lights work best during the flowering stage as it can enhance yield results.

Knowing the individual characteristics and varied benefits of each color spectrum of light can be quite useful in growing cannabis indoors. It not only helps you pick the right type of grow lights that best fits your requirements and needs. It can also prove handy in ensuring the health, quality, and good yield of your plants.