The Schlossgarten Oldenburg ("castle garden") is a 16-hectare public park in the city of Oldenburg, Lower Saxony, northern Germany, located between the Eversten district and the city centre to the north. At the northwest end is a lake and Elisabeth-Anna-Palais (built 1894–1896) and close to the northwest end is the Schloss Oldenburg.
The garden is a historic park in the style of an English landscape garden. It was created on behalf of the Duke Peter Friedrich Ludwig of Oldenburg by the former court gardener Friedrich Wilhelm Julius Bosse.
In 1803 and 1805, the Duke acquired meadowland near the Schloss Oldenburg to create a garden and began work on this in 1809 with detailed plans. The Duke himself worked on design drawings. The first gardens were largely destroyed during the Napoleonic occupation. In 1814, Duke Julius Friedrich Wilhelm commissioned reconstruction and the further investment to establish the garden. The Duke worked on the garden for 42 years and the appearance that has changed little to the present day.
Duke Peter Friedrich Ludwig combined his personal use of the garden with an effort to allow his subjects enjoyment of the garden too. From the beginning, large parts of the gardens were open to the public. The only condition for admission were appropriate clothing and civilized behaviour. This lasted until the 1950s when it was still the custom to enter the gardens in Sunday clothes. In the same decade, the former garden director, Max Heber, considered the needs of the general population of Oldenburg. Thus the garden became more available for general use. The garden suffered little war damage and was used as a kitchen garden for fruit and vegetables for a period. Some of the trees were felled due to fuel shortages.
From 1920, the garden became public property and was until 1946 owned by the Free State of Oldenburg. SInce then it became the property of the State of Lower Saxony. In 1952, a society was founded with the aim of preserving the garden. Since 1978, it has had official protected status. After an agreement in 2007, the Germany state contributes two thirds of the costs and the city of Oldenburg a third.