Mulch cultivation has become a common method for growing high-quality Satsuma mandarins in commercial orchards in Japan. Mulch cultivation, by facilitating timer-controlled watering, saves labor. To create technology to automatically determine the amount of watering needed, we developed the Marudori AI smartphone application and the Automatic AI Marudori watering system to support the production of Satsuma mandarins by the use of AI technology. The Marudori AI app uses deep learning to estimate water stress and indicate the need for manual watering. The fully automated Automatic AI Marudori watering system determines the amount of water required through the use of reinforcement learning. It bases its decision on the weather forecast and the water stress estimated by using deep learning from images of mandarins. Use of these methods to grow Satsuma mandarins in 2021 and 2022 produced high-quality mandarins with a sugar content of ≥10% and a citric acid content of ≤1.1%, meeting the criteria for shipment as a regional brand product.