A plant air purifier and associated method for purifying air, comprising: at least one grow container； a filter bed comprising a surface which is horizontal within 20 degrees of a horizontal plane； at least one plant which grows within the filter bed； a reservoir for containing water for watering the at least one plant； a mechanical watering device which waters the filter bed from the top down； a pump for pumping water from the reservoir to and through the mechanical watering device； and an air propulsion mechanism for propelling air through the filter bed.
