With fairly fast establishment rate, it can form a full cover in one growing season and has been adopted for roof greening in tropical areas(Chen, 2013; Dvorak and Volder, 2013).Sedum species assumes the Crassulace an acid metabolism (CAM) photo synthetic mode by closing their stomata in daytime under water deficit condition (Sayed,2001). At night time, stomata open to absorb carbon dioxide which is stored in leaf tissues for use in daytime photosynthesis when stomata are closed. Thus the transpiration rate of Sedum could be suppressed on hot days with dry substrate.