Blue light remains ideal for promoting vegetative, or leaf, growth. Reddish light when combined with blue light works well to promote flowering. Ideal blue light occurs at wavelengths between 400 and 480 nanometers, where one nanometer is equal to one-billionth of a meter. Ideal red light occurs at wavelengths between 610 and 690 nanometers. Fluorescent bulbs produce light from all colors in the visible light spectrum, including the ideal colors for promoting plant growth.
Quality of light alone is not the determining factor in successfully promoting plant growth. A light source needs to put out at least moderate levels of light intensity to encourage plant growth. Lumens measure light intensity. Fluorescent bulbs of all types generally offer a light output of around 39 lumens per watt of power utilized from a power source.
Constantly replacing light bulbs can be a costly venture. Luckily, fluorescent bulbs are some of the longest-lasting light bulbs on the market. Circular and CFL bulbs can last for up to 10,000 before they begin showing signs of deterioration. Fluorescent bulbs do not emit much heat, which means that consumers can situate these bulbs relatively close to a plant without scorching it.