The world is undergoing global warming, marked by increasing temperatures and atmospheric drying, driven by rising vapor pressure deficit (VPD). This exposes plants to heat- and drought stress and threatens natural ecosystems and agricultural productivity. To alleviate lethal thermal damage, plants transpire through open stomata. Yet, to limit the water deficit, plants conserve water by closing stomata, creating a trade-off between canopy cooling and water saving. In our project Plants under stress: decoding mechanisms of plant water use in response to drought and heat across scales (PWU-DAH), we leverage a multidisciplinary approach, combining plant ecophysiological, hydraulics, and soil physics perspectives to understand how plants navigate this trade-off under varying environmental conditions. Key questions driving this project include: (1) How do high VPD and heat interact to affect stomatal behavior? (2) How do soil moisture status and soil physical properties modulate these stress responses? (3) How can we accurately model and predict plant drought and heat responses across different agro-ecosystems? We will conduct controlled experiments with crops and trees in different soil textures, where temperature and VPD will drive plant stress to varying degrees. This will be followed by manipulative field studies in an agricultural field vs. a natural forest. We will integrate the empirical data into a soil-plant hydraulic model. Finally, this will be upscaled to ecosystem and crop models in collaboration with international experts, aiming to improve predictions of plant responses to climate stressors. The knowledge gained will be vital for assessing forests’ climate mitigation potential and addressing food security.