Grow lights are electric lights which mimic the wavelength of light that plants need to grow so that plants can grow without the need for sunlight. Plants primarily require blue and red light between the 400-500 and 600-700nm wavelengths. Other portions of the light spectra are not always utilised by the plants! Which is why if you got a regular light globe used in your kitchen, it COULD grow a plant, but most likely wouldn't, as most of the light spectrum emitted is wasted by emitting light at the wrong wavelength. Keep in mind that every plant has a slightly different requirement for light intensity, light spectrum, and the amount of exposure required.