An illuminance of 6400–8600 lx (600–800 fc) proved to be optimal when plants were grown under sunlight, high pressure sodium, and metal halide lamps. However, specimens placed under an even combination of Gro-Lux and cool white fluorescent lamps at 5400–7500 lx (500–700 fc) exhibited the most vibrant colours (although growth rates remained the same). Plants moved from the former to the latter light set up showed a significant change in pigmentation; green leaf blades turned bronzy and speckles on the pitchers darkened markedly.