Compact fluorescent bulbs are very efficient and effective light sources for encouraging plant growth especially because they offer the wavelengths (color) of light most readily absorbed by plants. According to Planet Natural, plants mostly utilize certain wavelengths, or colors, of light in the visible light spectrum. Specifically, red and blue light are the most beneficial colors of light for plant growth. Plants appear green simply because they reflect green light from the visible light spectrum.
This type of light bulb is not as efficient as high intensity discharge (HID) light bulbs, but they produce a wider color rendering than HID bulbs, according to ACF Greenhouses. Plants utilize more of the light produced by fluorescents than the light produced by HIDs. However, the intensity, light output and penetrating power of HIDs remain unmatched by any other type of light bulb technology, including compact fluorescents.
According to ACF Greenhouses, compact fluorescent bulbs emit much less heat than other types of grow lights like HIDs. Less heat production means that compact fluorescent bulbs can be placed relatively close to a growing plant without overheating the plant.
For optimal growth, plants need the right amount of light intensity on a daily basis. According to Natural Plants, mature plants that are leafy will do well under a compact fluorescent light that offers 15 to 20 watts per square foot of light intensity. Seedlings grow optimally under the same intensity, while seeds that are germinating do well with between 10 and 15 watts per square foot of light intensity.
Compact fluorescent light bulbs employ ballasts to govern power flow into the light bulb. They also provide a voltage to start the bulb when it is turned on. One of the benefits of compact fluorescent technology is that the ballast is constructed into the bulb itself, unlike HID systems in which the ballast remains independent of the bulb.
According to Home Harvest Garden Supply, the compact fluorescent light bulb was invented around 1980 as a more efficient alternative light source to traditional incandescent light bulbs. Compact fluorescent grow bulbs are typically rated to last for around 10,000 hours of regular use, according to ACF Greenhouses. They are relatively inexpensive, available at many stores, small in size and are designed to fit into traditional incandescent light bulb sockets. Compact fluorescent bulbs emit light in every direction, and adding a reflector gives the consumer control to direct the light to plants.