All plants need sunlight to survive and grow. Sunlight it is one of the ingredients for the plant photosynthesis, the process by which plants make food. However, that is not the only reason why plants need sunlight. In fact, light is the key component that allows plants to detect and respond to their environment. The natural sunlight is composed of several bands of colors that have different wavelengths and frequencies. However plants don’t absorb all the colors of the light.
Plants have different requirements of wavelengths for different stages of growth. Generally plants absorb light of wavelengths between 400-700 nm. This means that they essentially require red and blue light as the primary colors needed, along with lower amounts of secondary colors such as orange, violet, ultraviolet and deep red. The required spectrum of light by plants is referred to as photosynthetically active radiation. Plants have receptors for both red and blue light and require them at different frequencies depending on the current stage of growth. However, both the lights work hand in hand for the growth of the plant. Red light, that has a wavelength of 620-670 nm matches the absorption peak of chlorophylls and is responsible for providing energy to carry out photosynthesis. However, red light alone is not enough and in several cases it might cause unnecessary plant elongation leading to an unbalanced growth. Blue light has a wavelength 440-480 nm and also boosts the energy but balances out the negative effect of red light hence providing a more balanced growth.
Since the blue light keeps the growth balanced, it allows for proper vegetative growth. Therefore, during the vegetative growth, the blue light receptors of the plants are more active than the red light ones. On the other hand, during the flowering stage, the red light receptors become more reactive. The red and blue photoreceptors also control the internal circadian clock of the plants, which detects the length of the day, seasonal change and allows a smooth transition from vegetative to flowering stage.
While growing plants in an indoor environment, providing the correct light conditions for the plants proves to be one of the biggest challenges for indoor gardeners. HID bulbs such as metal halide lamps are full spectrum lights that mimic sunlight and do prove to be efficient in meeting the photosynthetic needs of the plants. However, since it’s an unnatural environment, sometimes plants fail to grow, probably because their circadian rhythm doesn’t set off. Also, plants are not dependent on light for photosynthesis only; hence other wavelengths are also required. These lights provide the light sufficient for photosynthesis but not for many other biochemical pathways. Research has shown that adjustment in light wavelengths can increase metabolism and helps in production of certain biochemicals that improve the quality of the plant.
LED Grow lights are a recent introduction to the world of indoor gardening. These lights are everything that MH and HPS lights are not: they are cost efficient, produce little heat, have a very long lifespan and run on very low energy. On top of that, they are powerful enough to grow all kinds of plants and give a great yield. One of the most distinguishing features of LED Grow lights is the ability to manipulate light wavelengths. Unlike other full spectrum lights, you can adjust the ratios of different light wavelengths to ensure proper growth.
Many indoor plant growers struggle with the transition from vegetative to flowering stage and because the correct requirement of the plants is not being met. This transition becomes comparatively easier with LED lights as the correct ratio of red and blue lights can be adjusted. Edible plants grown under LED lights can be more flavorful and rich. Also, the light spectrum manipulation leads to improved plant metabolism. Due to all these benefits, LED lights are more and more becoming the preferred technology for indoor growing.