Horticultural lighting system comprising a first string (22) of at least one light element (16, 40), a second string (24) of at least one light element (16, 40), both strings being electrically connected in parallel with each other, a power supply unit (12, 50,60,70) providing an AC current/voltage to the parallel circuit of the strings, and means for energizing (26, 42) the first string during a first half period of the AC voltage and the second string during a second half period of the AC voltage, so that each string radiates pulsed light, said first string and said second string being arranged such that different areas (32, 34) are irradiated. The lighting system is also to be used in an environment where living organisms are irradiated with light, or a greenhouse for exposing plants to pulsed light. A corresponding method is also claimed.