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.
Circa 1665, Peter Joseph's ancestor Augustin Le Neu had settled in Poppelsdorf near Bonn as court gardener of Archbishop-Elector Maximilian Henry of Bavaria.
Extensions to the city's fortifications gave him an opportunity to propose a plan for its beautification by the addition of gardens; however, this was not carried out because of lack of funds.
In 1816, he returned to Potsdam at the suggestion of Prussian forestry official Georg Ludwig Hartig and General Graf von Hacke.
[1] While still working as an assistant gardener, in spring 1816 Lenné received a commission from the Prussian chief minister Karl August von Hardenberg to renovate the grounds around his country house at Klein-Glienicke.
This work on Glienicke Palace, which would later become Prince Carl of Prussia's residence, laid the groundwork for Lenné's designs for the surrounding area of Potsdam, which he wanted to turn into a Gesamtkunstwerk.
[2] Despite centering his life around Potsdam and Berlin, Lenné remained attached to his Rhenish homeland and contributed to the further beautification of Koblenz, particularly in the Rheinanlagen, which was under his management until 1861.
His love of his work on the Rhine and Mosel made him decide to build the residence named for him, the Lenné-Haus, in which he wished to spend the evening of his life; however, the manner of his death did not allow this.