Woody ornamental plants are considered the key for well- designed landscapes; Callistemon citrinus is one of those plants. In arid and semiarid areas, Callistemon has been used in gardens and landscapes for its unique characteristics. This study was conducted to evaluate the performance of Callistemon in landscapes under different environmental stress conditions including water, and heat. Further, the potential of using 3D software SketchUp in landscape design was also investigated. Callistemon plants were grown under 100, 50 or 30% of field capacity with or without shredded hardwood mulch. When field capacity decreased, root: shoot ratio and water use efficiency were improved, but canopy temperature increased. The decreased water caused decreases in leaf greenness, chlorophyll a, shoot volume, root volume, leaf water potential, and transpiration rate. Mulch increased root volume and leaf water potential. Callistemon growth under shade structure angle and orientation was examined. Shade structures were installed at 90° and 70° to the ground and three orientations, south, east, and west. Transpiration rate was reduced under the shade. The plant’s response to heat was also examined. Plant were exposed to 45/35, 35/25, or 25/15 °C, d/n. The plant’s physiological response was tested after two weeks. Highest temperatures decreased Chl b content and SOD activity compared to control. In contrast, carotenoid content and H2O2 level increased under the highest temperature treatment. Catalase activity was increased at moderate but decreased under the highest temperatures. Designing a 3D model using SketchUp software was examined. The program function was evaluated, and the designed experiment was tested. Planning a site with shadows predicted was achieved. The work was done with greater precision and less effort. The program was effective in reducing time and cost. SketchUp can be successfully used in landscape work.