water-storing drainage layer: It is desirable to store water in green roofs to help plants survive through periods of dry weather. However, the dry-climate plants that thrive on green roofs will not survive unless excess water is rapidly drained from the plant root zone. The optimal combination of water storage and rapid drainage can be provided by several water-storing drainage products including well-graded granular inorganic media, dimpled plastic sheets, and ribbed fabric laminates.