Abstract: A light transmissive thin flexible covering for a greenhouse having two outside sheets. The two outside sheets have sandwiched there between an array of chambers which connect and hold the sheets together, the chambers are sealed and generally contain air and thus provide an insulating space. The cover can be placed or rolled over the framework of a greenhouse to provide an enclosed thermally insulated space. The structure of a greenhouse generally comprises an array of sequentially arched support rods or pipes. The support rods or pipes at either end have a base plate to which they attach. The ends of the structure are sealed to provide a completely enclosed interior space to protect plants during cold weather. The cover has ultraviolet reflective qualities which prevent the penetration of ultraviolet light into the interior or the degradation of the cover due to ultraviolet light.