The garden and grounds
Admiral Boscawen and his wife collaborated in the creation of the garden and, in particular, planted what later became known as 'Fanny Boscawen's Walk'. William Sumner commissioned Humphry Repton to propose improvements to the 420-acre park in 1800. Most of the recommendations in Repton's Red Book for Hatchlands were executed. A pleasure ground was laid out around the house with gravel walks leading to certain objects or viewpoints. The 'flower garden in the dell' and Fanny Boscawen's Walk were preserved. Repton also proposed a screen of planting to shield the house from the London to Portsmouth road.

Gertrude Jekyll
In 1900 Gertrude Jekyll submitted designs to Lord Rendel for south and west parterres. In 1914, a year after Lord Rendel's death, she made a design for planting the south parterre as a 'flower garden for June', which was has been restored by the National Trust.