Green wavelengths (500-600nm) are highly beneficial as a supplement to red (600-700nm) and blue (400-500nm) light within the Photosynthetically Active Radiation (PAR) spectrum. Unlike red and blue light, green photons penetrate deeper into the canopy, stimulating photosynthesis in lower leaf layers, which is especially advantageous for cultivating dense plants such as cannabis.
Charlie Benson, Co-Founder and CTO of Bloem
Typically, plant leaves appear green because they reflect 5-10% of green light, while the rest is absorbed. Chlorophyll absorbs mainly blue and red light, while carotenoids absorb primarily blue and green light. Plants also utilise various combinations of chlorophyllides, carotenoids, and phycobiliproteins to capture light from wavelengths that chlorophyll alone doesn’t absorb.
Green wavelengths have been shown to increase the net photosynthetic rate, leading to greater biomass accumulation. Including green wavelengths in supplemental or sole-source light recipes can boost both fresh weight and dry matter content. When combined with blue light, green wavelengths can increase total sugar concentration, acidity, and water-use efficiency, enhancing fruit quality attributes like texture, taste, and aroma.
In some plant species, green light acts as a shade signal that can promotes lateral root formation. As a partial substitute for red and blue light, green wavelengths also encourage graft union formation and support root regeneration in grafted seedlings. Supplemental green irradiation has been shown to increase seedling survival rates by enhancing antioxidant enzyme activity and stimulating photosynthesis.
Research indicates that green wavelengths can increase the leaf area index, resulting in broader, longer leaves with wider spaces between leaflets. Green wavelengths have been found to influence flowering in both short-day and long-day ornamental plants, though their effects vary across species and cultivars.
Importantly, green wavelengths enhance human visual quality, creating a healthier work environment and making it easier to detect pests, pathogens, and nutrient deficiencies. Green light can also mimic moonlight, allowing some wavelengths to be used without disrupting plant photoperiod-sensitive responses. This characteristic provides additional flexibility in controlled environment agriculture.
