Abstract Dawn leaf water potential (dawnΨ), leaf water potential (leafΨ) and stem water potential (stemΨ) were measured on mature leaves to determine non-irrigated vine water status in vineyards during the growing season. StemΨ was the most discriminating indicator for both moderate and severe water deficits. The difference between stemΨ and leafΨ (ΔΨ) provided an indirect measurement of mean leaf transpiration which varied with soil moisture conditions and vapour pressure deficit in the atmosphere. The use of stemΨ as an indicator for grapevine management in both non-irrigated and irrigated vineyards is discussed.