Does Green Light Affect Cannabis

The answer is “Yes”. Green light affects the growth and development of cannabis. It is well known that blue light is beneficial for vegetative and red light is useful for flowering. But effects of green light on cannabis are often overlooked. Plants appear green as they absorb red light and blue light more efficiently and reflect green light. Meanwhile, human vision is more sensitive to green light than other visible lights. That is why green light is seen as negligible wavelengths for cannabis. In fact, only less than 10% of the green light is reflected. The rest of green light is still absorbed or penetrated by the leaves of plants. Thus, green light affects cannabis growth and it is important and useful for cannabis.

What is green light

As known, plants sense light and respond the light with photosynthesis. Light spectrum related with plant growth is divided into UV light (100 - 400 nm), blue light (400 - 500 nm), green light (500 - 600 nm), red light (600 - 700 nm), and far-red light (700 - 850 nm). This range of wavelength sensed by plants is not all perceivable by human eyes. Wavelength ranges from 400 nm to 700 nm is defined as Photosynthetically Active Radiation (PAR). photosynthesis is most effective within the PAR. Green light ranges from 500 to 600 nm and at the middle of red light and blue light in PAR range. Sunlight emits the nearly same quality of red, blue, and green light. It seems that green light has less impacts on plant growth as the lower absorption by chlorophyll. Although green light is less absorbed, it transmits deeper into to the canopy. Thus, it is indispensable for cannabis growth.

Effects of green light on cannabis

Green light is contained in natural lights. Researches shown that green light was beneficial for cannabis growth. Though a small amount of green light is reflected, the rest of green light penetrate deeper to plant’s tissues, reaching greater effects to cannabis. Effects of green light on cannabis include influencing photosynthesis, morphology, and flowering.

• Photosynthesis

Unlike red light and blue light, not only chlorophyll a and chlorophyll b but also other photoreceptors utilize green light for photosynthesis. There are just a little chlorophyll during seedlings stage of cannabis. Green light allows cannabis to photosynthesize more actively by themselves. When cannabis are shined by green light, upper leaves of cannabis reflect about 5 to 10 percent green light and they also absorb certain amount of green light. The rest of green light filter through the lower leaves. Green light that transmits to the lower leaves slower the leave senescence, keeping health of the leaves for better photosynthesis. Green light also influence photosynthesis directly. Researches shown that green lights is more efficient to photosynthesis than red and blue light. Green light can improve photosynthesis and help cannabis plants grow more substantially.

• Morphology

Green light is able to affect the morphology of cannabis plants through influencing the growth of leaves and stems. Smaller leaves and shorter stems are formed in lower level of green light condition. In contrast, higher green light proportion promotes the growth of seedlings, enlarging leaves and elongating the stems. As shown as researches, green light and far-red light can trigger the shade avoidance syndrome symptoms. Green light is easier to penetrate the leaves than others. When plants sense the green light (the green light should reach certain intensity), they realize that they are in shade. To gain more light and energy, plants will extend their stem and enlarge their leaves, growing taller length and larger leaves. In sum, green light has effects on morphology on cannabis plants, but the specific effects are related to the intensity of green light.

• Flowering

Flowering is generally regulated by phytochrome and cryptochrome. Phytochrome is more sensitive to red light while cryptochrome is more sensitive to blue light. Both of them absorb green light as well, but in a significant lower efficiency. Research shown that the same intensity green light, and red and far red light had equal performance. Since the low phytochrome and cryptochrome sensitivity to green light, green light is expected to regulating flowering in indoor cannabis growing to reach a long day photoperiod without disturbing night cycle. Another reason for the regulation of green light on flowering is the improvement of photosynthesis. Green light penetrates deeper through the leaves and drives the photosynthesis better. Therefore, green light can promote flowering of cannabis plants.

Green light function

Since green light is less absorbed by plants, it has slight impact on night cycle photoperiod of cannabis. In addition, growers may not spot the true color and the early stage of the cannabis in time. Other issues like nutrient insufficiency, pest and disease also may not be perceived clearly. Supplying green light at night is ideal to work to cannabis without destroying the night cycle photoperiod.

However, green LED grow lights are uncommon on the market. Green LEDs are impractical for commercial cultivation because of the less electrical and photosynthetic photon efficiency. LED grow lights only with a combination of red and blue light appear totally ‘purple’ and there is a risk of eye strain for growers. White LEDs, component of full spectrum LED grow lights, are the better choice for improving cannabis growth. Full spectrum LED grow lights not only supplement green light but also deliver red and blue light, offering comprehensive lighting for cannabis growth. Therefore, full spectrum LED grow lights have more natural appearance and higher efficiency.