This dataset contains observations of leaf phenology of two forest tree species, European beech (Fagus sylvatica L.) and silver fir (Abies alba Mill.). This dataset is highly relevant : observations were carried out over 14 consecutive years, from 2006 to 2019 on 772 trees distributed in plots along two altitudinal gradients located on Mount Ventoux, France. One transect is located in the communal and state forests of Beaumont du Ventoux on the north side of the mountain (from 968 m to 1522 m) and includes both species. The second transect is located in the communal forest of Bedoin on the south side of the mountain (from 875 m to 1537 m) and includes only beech. All plots concerned are managed by the French Forest Service (Office National des Forêts, ONF). The originality of these observations stems from the fact that Mont Ventoux is located at the southern margin of the distribution areas of both beech and silver fir in Eurasia, and at the crossroads of two major biogeographical climate zones, Mediterranean and Alpine. Budburst, leafing and leaf senescence were observed. Between 2006 and 2019, 18475 individual bud development states (+2234 of leafing) and 10224 leaf senescence states were observed. A total of 7258 observations were made on 169 Abies alba trees and 23675 observations on 603 Fagus sylvatica trees. The protocol used is based on the BBCH standard published by Meier (1997). It is described in the file named «Description_BBCH_stages.pdf». The description of the variables presented can be found in the files named "ANFS-D-23-00044-metadata.tab".