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Does the color of light affect plant growth? The answer is YES

If you want to know about the influence that visible range light has through its different wavelengths (colors of light) on your crop, it is because you have surely wondered ¿does  the color of light affect plant growth? And the answer is yes.  But how?  

Light is made up of a set of electromagnetic radiations that allow the propagation of energy with different wavelengths. Every crop needs light (natural or artificial) to thrive, and that's when the waves provided by the visible light spectrum intervene.

This element (light) and its waves are essential for plants to synthesize nutrients from the soil and thus produce the necessary organic matter that, in union with other elements, allow their optimal growth and development.

If you grow plants indoors you must guarantee the conditions that favor the optimal development of your plants, as if they were in a natural environment.  Therefore, controlling the lighting of your crop will be paramount. If you fail to meet the lighting needs of your plants, your cannabis crop will never reach the desired yield.

But don't worry, the good news is that indoor LED grow lights can also provide your plants with enough energy to carry out their processes, with ideal power and intensity, which can even be controlled by yourself. Of course, first you must know very well the type of plant you are growing and what are the particular needs they present.

In the following lines, you will find specific information related to the effect of light colors on the growth of Cannabis plants, in addition, you will know the importance of good lighting during each of the growth stages of your crop, and how you could stimulate their growth with the help of certain colors of light.

Does the color of light affect plant growth?  Specifically about Cannabis

After reading this we assure you that you will take much more seriously the color and intensity of the light you are administering to your crop. Now let's answer: Does the color of light affect plant growth?

In terms of crop lighting, there are three important aspects: quantity, quality and duration. In the following lines we will emphasize the second of them "quality", which is related to the color (wavelength) that the plant will receive.

When it comes to the Cannabis plant, it is important to possess sufficient theoretical and practical knowledge about the conditions in which plants should remain inside indoor or artificial crops, as they are quite delicate in terms of their growth. In addition, if it is not taken care of in the proper way, even if the plant grows, its flowering can be affected. This could generate unwanted effects when used for consumption, especially with respect to its potency and taste.


Through various studies, it has been shown that the most important colors of lights for cannabis crops are red light, for growth and blue during flowering. To a lesser extent the rest of the colors that make up the visible light spectrum, such as yellow, orange or violet, which intervenes in the smell and taste.

How do colors affect Cannabis?

Like any other living being, plants are also able to perceive colors, the difference is that plants do it through pigments, which are the molecules responsible for transforming the energy from light into another type of energy: chemical energy, which is what allows the plant to live.

Although it may seem incredible, these pigments are the ones that absorb light, for this reason they are also called photosynthetic or vegetable pigments.

It is precisely the colors of these pigments that allow your cannabis plants to absorb the wavelengths of the light source. Among the most common pigments of Cannabis, we can find chlorophyll, carotenoids, flavonoids and anthocyanins.

Now, let's dig a little deeper into the colors of light that have the greatest impact on cannabis cultivation:

  • Red light

Cannabis has a photoreceptor that reaches its maximum absorption in the red light spectrum. Thanks to this pigment, the plants manage to reach a large size, and in summer times (which is when there is more red light) it activates a hormone that is responsible for keeping the plant green thanks to the fact that it prevents the decomposition of chlorophyll.

On the other hand, red light also intervenes in the process of flowering and seed production and to a lesser extent, in the flavor, increasing the "terpenes" (which are responsible for providing flavor to Cannabis).

It is important to note that an excess of red light could also unwantedly increase the proportion of male seeds.


  • Blue light

The photoreceptor involved for this color is called "cryptochrome", which, among other things, inhibits the intervention of the phytohormone called auxin, which prevents the stretching of the stem disproportionately.

Blue light also contributes to increased lateral shoot formation, wider bud growth, and branching, bringing a stronger, more compact look to your plants.

Additionally, it intervenes in the opening of the stomata, which leads to an increase in the metabolic speed of your Cannabis plants, generating growth and development in less time.

This color also participates in the orientation of the leaves and apexes towards the light and inhibits the excessive formation of leaves in the bud. Contrary to red light, an excess of blue light increases the proportion of female seeds.

  • Green light

According to contemporary studies, plants do not have specific receptors for this type of color, therefore, the effect of this color on the Cannabis plant has proven to be quite insignificant.

Whereas, in the case of the rest of the colors of the visible spectrum, such as yellow or orange, its effect is similar to that produced by red light, and the effect of indigo and violet colors is similar to blue.

As an interesting fact, plants are also able to perceive ultraviolet light, which causes plants to increase the pigment "anthocyanin" to protect themselves from it, an effect that could generate a bluish-red color in their leaves.

So far, as you may have noticed, the colors that your cannabis crop will need the most are blue (during growth) and red (during flowering).

Now that you know, if your plants are about to bloom, then the red spectrum will be the most suitable as it simulates the spectrum of autumn outer space (which is the time where cannabis blooms when it is in natural environments).

Green light, on the other hand, could be useful when the lights are off, as this would not cause any unwanted or stressful effects during the flowering of your crop.

LED lights have managed to optimally meet each of these lighting needs that we have mentioned, and in some cases, they have even surpassed many of the lighting systems traditionally used in cannabis cultivation, such as HPS lamps, since LEDs produce less heat and have greater energy efficiency.

Important care within a Cannabis crop

The energy provided by light gives the Cannabis plant signals about the beginning and end of each of its cycles. Therefore, when you have an indoor crop this should also be recreated by the growth lights. The choice of lighting system for growing Cannabis will depend on the variety you are growing, its characteristics and the growth phase in which it is located.

As already indicated, the most suitable light spectrum for the growth and flowering phases of cannabis are blue and red light, respectively. In addition, another factor that is accompanied by lighting is temperature, so that heat will also be a variable that you must pay attention to in your crop.  In that case, LED lamps are ideal due to their low heat emission, although you may need to increase the temperature in your grow room in cold weather.

The cultivation of Cannabis indoors has become popular since the climatic conditions in many regions, especially in those of the north, where the lighting and the atmospheric weather can be very changeable, the variations in the sun, rain and humidity, can cause many inconveniences for your cultivation and the appearance of diseases. All these variables can be controlled more efficiently, through indoor cultivation.

The best option for Cannabis crops are led Grow Lights

The growing popularity that LED grow lights for indoor crops have had in recent years is due to all the advantages it has compared to other types of bulbs, such as HPS.

Among the main advantages of using an LED lamp is the low proportion of electrical energy consumption, because they are energy efficient. In addition, its life span is longer.


Secondly, their heat emission is quite low, which has made it possible for plants to receive all the benefits they require from lighting without suffering the harmful consequences of excess heat in a grow room, which can be expressed through stains and burns.

The light spectrum is also an advantage very pursued by growers, since LED grow lights have the ability to provide the full spectrum of visible light that your Cannabis crop requires, without you having to buy different lamps or bulbs.

Relevant aspects about lighting in plant growth

In general, the color of the lights used for the lighting of your cannabis crop will completely determine the success or failure of your harvest. Since the growth of the stem and leaves will depend on it, as well as the flowering of your Cannabis plants. As you may have noticed, returning to the question asked at the beginning, does the color of light affect plant growth? the answer is totally yes.

A good quality of lighting with the right colors will bring countless benefits to your Cannabis crop, improving growth, coloration, flavor and aroma, whether for personal consumption or for sale, using the right lighting will guarantee you a quality product.

Also, you should remember that lighting is closely related to the characteristics of your crop, the environmental conditions and the stage of growth in which they are. Therefore, LED lights represent the best option so that you can cover the lighting needs of your crop, covering the spectra required in each of the phases.

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