Why do regular light bulbs have different effects on plants than fluorescent lights?
Regular (incandescent) light bulbs create light with a hot filament. This light is relatively reddish and contains very little blue, violet, or ultraviolet light. Since it comes from a hot, thermal source, this light covers all the wavelengths from infrared to the green and blue range of the spectrum continuously and smoothly, although its intensity peaks in the red and orange range of the spectrum. Fluorescent lights, on the other hand, create light through the fluorescence of atoms, molecules, and solids. The light is not created by hot materials so it contains certain regions of the spectrum, often including blue and violet light. Depending on the exact make-up of the fluorescent lamp, this light may include wavelengths that are particularly important to a plant’s metabolic processes.