What is the Ideal light spectrum for plant growth?
Ideally plants will grow in the range of 400-700nm. This covers a range of the visible light spectrum from blue to red. There are different types of artificial lighting on the market these range from fluorescent to HID lighting and each has their merits. Typically HID lighting is used more widely than fluorescent lighting, particularly if the growing area is large. Plants do not see light the same way we do. Plant available light is commonly referred to as PAR Watts. PAR stands for Photo synthetically Active Radiation. As the name suggests this corresponds to light that most encourages Photosynthesis. Maximum photosynthesis occurs at two peak wavelengths, 435nm (blue) and 675nm (red). As human beings, we judge light by its brightness, or lumen intensity but the brightest lamp is not necessarily the best for plant growth. The lumen output does, however, provide a guide as to the effectiveness of the lamp.
