Today's form of the Hertener lock park goes back to the Duesseldorf Hofgärtner Maximilian Friedrich Weyhe. He redesigned the former French garden between 1814 and 1817 into an English landscaped garden, preserving formative elements of the symmetrical Baroque garden, such as some avenues and the Orangerie building. The former maze is no longer preserved, but the natural theater is - restored in a simplified form - now used again for plays.
Between the middle of the 19th century and the First World War, the owners of the castle in the southern part of the garden had two fish ponds and a 200-hectare mixed forest - now called Castle Forest - create. Also from this time come two Kavaliershäuser at the entrance to the northern edge of the castle grounds.
After 50 years of neglect in the aftermath of the First World War, the park was completely overgrown. Their restoration was carried out at the same time as the restoration of the castle buildings from 1974 and lasted until 1982. Subsequently, the park was opened to the public. Of its 30 hectares, 14.5 hectares are wooded and five hectares are lawns. Another three hectares are occupied by water surfaces, while roads make up another two hectares. [4] Among the 3067 [4] trees are rare shrubs such as a 125-year-old handkerchief tree, originally from the Chinese highlands, a large-leaved magnolia and lily-of-the-valley native to North America. The exotic plants were brought to Herten by the diplomatically active castle owners from distant lands. In total there are over 200 different tree species in the park. Because of its cultural and historical significance, the Hertener Schlosspark was listed as a historical monument in 1988.