Compare the features yourself to pick the right light for your grow operation.
Engineering and Design
Fluorescent lamps work by passing electricity through a gas-filled tube that contains mercury. When the mercury atoms are excited by electrical current, they give off ultraviolet light, which is invisible to the human eye. The UV light reacts with phosphors coating the inside of the tube, causing them to give off light in the visible spectrum.
The type of phosphors in the coating determine the colors of light given off, although somewhat imprecisely. The mercury and other compounds in fluorescent lamps are toxic and need to be handled with care against exposure and add toxic waste to the environment.
LEDs (light-emitting diodes) produce light by running electricity through a very small, solid semiconductor that glows in a very specific wavelength. Full-spectrum LED grow lights use an array of diodes to shine light of different wavelengths in a specific combination to produce the colors desired for optimum plant growth and yield.
The color of light is critical to plant growth. While plants have evolved to thrive in sunlight, they use light of different wavelengths (colors) for different purposes. Fluorescent lights attempt to replicate that light with different phosphors, while LEDs can be designed to give off light in very precise wavelengths. Much of the light produced by fluorescent tubes is yellow and green, which makes the light appear white to humans, but is not readily used by plants.
Fluorescent tubes are large and made of thin glass, making them fragile and bulky. LEDs are small, solid, and much less susceptible to damage from rough handling. LEDs also last much longer than fluorescents, as much as 6-20 times longer.
Heat Output and Noise
While they generate less waste heat than many other lamps, fluorescent lights still generate much more heat than LEDs. The energy used to create that heat is wasted in terms of plant growth and visible light, and must often be ventilated and closely monitored for both plant health and the danger of burning leaves. As fluorescent lamps age, they rapidly lose light intensity and can have an annoying buzz and flicker, whereas LEDs are totally silent and don't lose intensity as quickly.
There's no question that grow light fluorescent lighting setups cost less initially than LEDs, but that's not the whole story, especially if you're in business. Because LEDs use a lot less electricity and generate less heat, their operating cost is much lower than fluorescents. Add in the savings on maintenance plus healthier plants and higher yields, and LED grow lights are significantly less expensive in the long run.
LED grow lights outperform fluorescents in operating costs, maintenance, and most importantly, plant health and yield. While fluorescent setups may cost less initially, there's no doubt that LED grow lights are the best choice for serious growers and indoor gardeners.