Derreen Garden lies on a promontory in Kilmakilloge Harbour on the Beara Peninsula, in Tuosist parish, near Kenmare in County Kerry (Republic of Ireland). Henry Petty-Fitzmaurice, 4th Marquess of Lansdowne (1816–1866) initiated the planting of the garden in 1863, but it was his son, Henry Charles Keith Petty-FitzMaurice, 5th Marquess of Lansdowne (1845–1927), who from 1870 onwards gave the garden its present shape. Today it covers more than 60 acres and includes nearly 12 km of paths.
The land around Derreen garden was the seat of the Mac Finin Dubh O'Sullivan family, a branch of the O'Sullivan Beare, from around 1320. After the Cromwellian conquest of Ireland (1649–1653) the property was confiscated and was granted in 1657 to Sir William Petty, physician of Oliver Cromwell, as reward for his services. The Mac Finin Dubh O'Sullivans became a large tenant of Petty. The estate came into the ownership of the Fitzmaurice family, when in 1692 Petty's daughter Anne married Thomas Fitzmaurice, 1st Earl of Kerry, whose grandson William Petty, 2nd Earl of Shelburne, became Prime Minister of Great Britain and in 1784 was created Marquess of Lansdowne.
After the last male member of the Mac Finin Dubh O'Sullivans had died in 1809, the tenancy of the estate passed to Peter McSwiney, who was married to a niece of that family. In 1856 McSwiney was evicted from Derreen by William Steuart Trench (1808–1872), the land agent of Henry Petty-Fitzmaurice, 3rd Marquess of Lansdowne (1780–1863), for being some years in arreas of rent. From 1857 onwards the house and its grounds were leased to different gentlemen. The last tenant was James Anthony Froude (1818–1894), an English historian, novelist, biographer, and editor of Fraser's Magazine, who leased Derreen between 1868 and 1871. In 1864, shortly after succeeding his father, Henry Petty-Fitzmaurice, 4th Marquess of Lansdowne (1816–1866) spent some days at Derreen with his wife. Being taken by the beauty of the property, he decided to live there for part of the year. However, this never came to fruition, as in 1866 he suddenly died of a stroke at his London club.