Effective management of cropping and horticultural systems depends on effective management of water resources. Water availability and impacts on water quality are increasingly problematic for irrigated arable cropping and outdoor horticulture and require more efficient use of water resources. Growers need to demonstrate efficient and sustainable use of water to remain competitive. Developing innovative site-specific management approaches, such as precision irrigation, that combine knowledge of the whole system—soil, crop and irrigation performance—with spatio-temporal water applications can improve crop water productivity and energy-savings with less impact on the environment, when well designed and well managed. The aim of this chapter is to discuss the latest state-of-the-art technologies that enable precision irrigation management systems, with examples of their use for outdoor horticulture. The chapter includes: