Over the last 30 years, high-pressure sodium lamps (HPS) have brought proven benefits to horticulture. The colour spectrum is rich in red and far-red light, which stimulates elongation growth and optimises fructification. Therefore, it is best suited to increase yield. Further, the heat emission of the lamps supports assimilation by slightly increasing the leaf temperature. This is especially an advantage during the colder months when low temperatures normally reduce plant growth.
In other words: HPS light helps to shorten the harvest cycle.