Peter Joseph Lenné (the Younger) (29 September 1789 – 23 January 1866) was a Prussian gardener and landscape architect. As director general of the Royal Prussian palaces and parks in Potsdam and Berlin, his work shaped the development of 19th century German garden design in the Neoclassical style. Laid-out according to the principles of the English landscape garden, his parks are today part of the UNESCO World Heritage.
Lenné was born in Bonn, then part of the Electorate of Cologne, the son of the court and university gardener Peter Joseph Lenné the Elder (1756–1821), and his wife, Anna Catharina Potgieter (also Potgeter), daughter of the mayor of Rheinberg. The Lenné family descended from the Prince-Bishopric of Liège, Peter Joseph's ancestor Augustin Le Neu had settled in Poppelsdorf near Bonn as court gardener of Archbishop-Elector Maximilian Henry of Bavaria about 1665.
Having obtained his Abitur degree, Peter Joseph Lenné decided to adopt the family tradition. He began his apprenticeship as a gardener in 1808 with his uncle, Josef Clemens Weyhe, court gardener at the electoral Augustusburg and Falkenlust Palaces, Brühl. At the instigation of his father, he also took university courses in botany.
From 1809 to 1812, Lenné took many study trips, paid for by his father, which took him to Southern Germany, to France, and to Switzerland. In 1811, he completed a long internship in Paris with Gabriel Thouin, who was then one of the most famous garden architects in Europe. This made him a master landscaper. On another of these trips, Lenné made the acquaintance of the creator of the English Garden in Munich, the landscape gardener Friedrich Ludwig von Sckell, who would have a lasting influence on Lenné's work.