Intraspecific trait variation is a key variable in evolutionary biology as it contains information on past adaptational processes as well as future evolutionary potential of species. Recently, intraspecific trait variation has become an important data source for various research disciplines such as species distribution modelling, eco-evolutionary research, gene-environment associations, tree breeding and many more. Yet, systematic and range wide data for long-living organisms such as trees are rare. This is partly because only a few long-term experiments on intraspecific trait variation still exist in Europe. What is more, their data are often stored in non-digital format and are thereforehard to find, access, interpret and use. Here we present a provenance trial database aiming to fill this gap by compiling information on intraspecific trait variation for ten European tree species together with necessary metadata on trial sites and provenance origin. In total, measurements from more than 1,900 provenances growing in 75 trial sites across Europe provide nearly 1 million observations on growth, phenology, survival, competition, fructification, resilience, and other important life history traits. This  provenance trial database was prepared as part of the European HORIZON OptFORESTS project. It represents one of the largest databases on phenotypic variation in trees that has been published to date in terms of number of species and provenances tested and is the first initiative aiming at compiling such data across European countries with open access.