Knowledge about the seasonal dynamics of tree growth and its relationship with environmental factors is necessary to eliminate the uncertainty due to ongoing climate change and for more precise growth modelling when re-measurements are done periodically. Despite the increasing number of studies monitoring seasonal wood formation, a considerable part of European forests, including Estonia, lacks such information. In this article, we present a date-dependent model for determining the share of seasonal radial growth for the three most common tree species in the region (Scots pine, Norway spruce and silver birch) for Estonian conditions. Since seasonal tree growth monitoring data were unavailable for Estonia, we used published seasonal radial growth data from Lithuania by