Accurate irrigation is one of the most important elements in successful orchard farming. Too much water can suffocate roots and lead to diseases; too little will stress the trees, threatening growth and production. Growers can use a variety of tools to measure soil moisture and calculate tree water use, but wouldn’t it be simpler if you could just ask the tree if it is thirsty? We’ve had a device that can do this for quite awhile—a plant pressure chamber measures a tree’s water potential, something like the way we measure our own blood pressure. But the pressure chamber was seen as a tool for research, not a management tool for growers, and no one had developed the baseline data needed to make the tool practical for use in the field. Recognizing the potential for benefit to growers, UCCE farm advisors Rich Buchner and Allan Fulton put together a team of UCCE advisors, specialists, and campus-based faculty to assemble the baseline data for prunes, almonds, and walnuts. With help and training from UCCE, more and more growers are beginning to feel comfortable using pressure chambers for real-world water monitoring, and in this way they are gaining a better understanding of how much water their trees need.