Illuminating device for plant cultivation

An illuminating device for plant cultivation comprising:

• a base;
• at least one light source mounted on the base and emitting light in a direction of a growing plant;
• at least one light converging plate mounted on the base and located in an optical path of the at least one light source, and being configured to converge the light emitted by the at least one light source;
• a position-adjusting device mounted on the base and being connected to the at least one light source or the at least one light converging plate and being configured to change a distance between the at least one light source and the at least one light converging plate;
• the
• position-adjusting device moving the at least one light source or the at least one light converging plate relative to the base and thereby change the distance between the at least one light source and the at least one light converging plate, wherein an illumination field of the illuminating device is altered;
• a distance sensor facing toward the direction in which the light is emitted from the at least one light source, and detecting a distance between a growing plant and the distance sensor;
• the distance sensor being electrically connected to the position-adjusting device, the position-adjusting device changing the distance between the at least one light source and the at least one light converging plate responsive to the detected distance between the growing plant and the distance sensor such that the illumination field of the illuminating device increases in correspondence with the detected distance being reduced as the growing plant grows higher.