These data comprise 12 different measurements, including single traits (e.g. needle length) as well as repeated, yearly phenology measurements over time (autumn 2022 to summer 2025) from a common garden trial of juniper trees planted in Cardrona, the Scottish Borders. Seeds from 16 natural juniper populations were germinated, and seedlings were raised in a glasshouse at the UKCEH, Edinburgh, then planted in the field in August 2022. The field site is a seminatural research site owned by Forestry and Land Scotland and managed by Forest Research. It occupies a hillside at approximately 350 metres of elevation and with a west-southwest aspect, and grazing is controlled by deer fences and culls. This deposit also includes R scripts that can be used for transformations and analyses of the data, including univariate and multivariate analyses of quantitative data and correlating these measurements with climate variables (downloaded for each source population location from the CHELSA database). These plants were part of a PhD project conducted to evaluate the standing genetic diversity and adaptive capability of natural populations. Full details about this dataset can be found at https://doi.org/10.5285/6952cab2-35be-494f-9253-5873e7fa7f74