The study investigates the growing processes of Pittosporum Virgatus and Aralia in screen houses. These processes are labor intensive, and the large numbers of workers involved in the various operations cause bottlenecks that affect costs and working efficiency.The objectives of the present study were to improve work methods of green ornamentals farms, to increase productivity and to develop an optimal screen house layout in order to maximize the total revenue. The research was performed during the years 2006-2007 in two modern farms in the central part of Israel. The farms consist of 7 and 11 hectare of Pitosporum and Aralia screen houses. On each farm, work studies and time measurements were performed in the various stages of harvesting. A computer simulation model was developed to find an optimal design of a screen house layout. Simulation results showed that the optimal length of a screen house is 22 m. Furthermore, the optimal width of the screen house was determined as a function of the number of workers and the pace of their performance. In addition, the optimal location of the cart to transfer the crops to the packaging house was determined.