This study presents the first detailed dendrochronological research of old trees in Olexandria park, a historical landscape garden established by the Branicki family in the late 18th century in Ukraine. By analyzing tree-ring data from the oldest trees in the park, we aimed to refine our understanding of its developmental stages and verify long-held historical narratives. Our results reveal that native species, Quercus robur and Pinus sylvestris, are the oldest tree specimens in the park, with the piths dating back to the late 18th century respectively. This suggests that the initial stage (1787–1791) of park development may have begun earlier than previously thought or that existing old-growth forest trees were integrated into the park's design. Additionally, the age of the oldest non-native species indicates they were planted during the third stage of development (1815–1865), with further plantings occurring during the fourth stage (1865–1918). Our study supports the idea that this historical park has been continuously modified and developed throughout its history from the late 18th to early 20th century. Contrary to some long-held narratives, most of the studied trees are not gifts from Catherine II or Grigory Potemkin, nor were they planted by the Romanov family; rather, some are older than previously expected.Read less <