An example adaptive Photosynthetically Active Radiation (PAR) sensor and controller system includes a hemispherical incident, translucent light housing that accepts light from above or from the sides in an artificial grow environment. A linear light sensor is positioned to receive light for the artificial grow environment, and an identical light sensor that is isolated from all light for the artificial grow environment. The identical light sensor functions as a temperature compensation device for the active photosensitive cell, A circuit supplies 0 to 10 VDC to a dimming input of a constant current LED driver to linearly dim an LED light according to at least measured intensity of light, from full-on to full-off as a direct inverse of the amount of sunlight received by linear light sensor, so that more sunlight causes more dimming of the LED light until at a predetermined threshold, the LED light is shut completely off.
