Light energy, provided by Sun, is essential in the photosyntesis process, without which life on Earth could not exist. Unfortunately, having even a little control over the Sun will always remain a dream of growers because the star in the centre of our galaxy produces and supplies energy only on its own terms, regardless of our needs. It was clear that the needs of today’s world will require independent sources of the artifical light. Since the invention of the first light bulb, the scientists made a great effort to provide us with product which could replace the Sun in the photosyntesis process. The first invented traditional lamps were able to fulfill the growers needs only partially and even though their effinency was questionable, this outdated technology still has its true believers. In the beginning, the invention of the LED technology (Light Emitting Diode) did not bring any revolution – the technology was expensive, poorly developed and available only to a handful of people. After over 60 years of research, experiments and lowering the prices, the LED Grow Lights market has changed itself forever. Thanks to outstanding performance and energy efficiency, products based on the LED technology became an unquestionable market leader. It became obvious that quality of the lamp is not determined by number of lumens but by more complicated factors like PAR, PPF, PPFD and DLI, which are described below.