Lamp (1) for growing plants in a greenhouse, said lamp having an elongated shape with a longitudinal axis (20), comprising at least one LED (8) and at least one connector (5, 18), preferably two connectors, for connecting in series two adjacent lamps (1, 1'); wherein the axis (19) of the connector (5, 18) allowing to connect two adjacent lamps is oriented orthogonally with respect to the longitudinal axis (20) of the lamp itself.