The ongoing climate change causes unprecedented challenges for agriculture. The modern farmer requires advanced knowledge about plant stress physiology to avoid losses in crop production and quality. But exactly how much water does a plant need to grow satisfactorily? Our laboratory investigates the physiological mechanisms and biophysical principles that govern plant-water relations and hydration status. We are using traditional and cutting-edge techniques to monitor plant-water relations in laboratory and field conditions. Our data provide the foundation for developing precision irrigation practices that promote water savings and sustainable agriculture.