Greenhouse flower gardens are highly vulnerable to internal and external climate factors like sunlight, temperature, humidity, and carbon dioxide. An appropriate control mechanism for the greenhouse flower garden environment is required to maximize the growth and quality of the flowers. In this thesis, the nonlinear coupled multiple-input multiple-output dynamic model of greenhouse flower garden climate is obtained and transformed to its equivalent linear and decoupled model using feedback feedforward linearization and decoupling technique. Then, a fuzzy sliding mode controller is designed based on the linearized and decoupled model to obtain a fast response with less overshoot and compared the results with SMC and PID controllers. The reference tracking and disturbance rejection performance tests are performed by considering different reference and disturbance values for the daytime summer season operations. The performance of these controllers is evaluated using performance measures such as overshoot, settling time, and rise time. In the tracking test, the system response of indoor temperature at a reference value of temperature 27°C and humidity 22g/m 3 for the FSMC gave rise time, settling time, and overshoot of 5.7837min, 10.3013min, and zero (0), respectively. And also, the FSMC humidity response gave a zero overshoot with a settling time of 5.2201min. The result showed that FSMC provided a fast response in both temperature and humidity responses. In the disturbance rejection test, the external disturbances such as intercepted solar radiant energy, outside temperature, and outside humidity were variable step type changes and time varying while the humidity and temperature set points were step type changes. These external disturbances are also rejected by FSMC for both humidity and temperature responses. In general, the performance measures of the proposed controller for both performance tests informed that the FSMC indoor temperature and humidity response is better than those of the SMC and PID controllers for the designed system. Keywords: Climate control, Flower Garden, Fuzzy-Slide Mode Controller.