Dyffryn (also known as Duffryn)

There was a courtyard garden to the west of the house in Moorish design. This no longer survives. The walled kitchen gardens, which probably originated in the 16th or 17th centuries were further west and south of the house. To the south of the kitchen garden Mawson laid out his series of intimate enclosures. These are arranged with paths, walls, compartments and clipped yew hedges. Each compartment has its own character both of design and planting, a result of Mawson's professional skills and Reginald Cory's profound knowledge of plants.

The south-west facing terrace has a herbaceous border running along its full length. Beyond the border are the garden rooms. These include the Lavender Walk, Paved Court, Bathing Pool Garden, Rose Garden (also called the Round Garden or Topiary Garden), Theatre Garden (also known as the Japanese Garden) and the Pompeiian Garden. Other features include an arboretum containing many notable trees, and an informal area of lawns and woodland clearings known as the West Garden.

An enclosed garden was set in the south-west corner of the grounds. This was used by Reginald Cory for his large-scale dahlia trials, which improved the popularity of the dahlia plant. This garden area is no longer extant. A lake was planned at the south of the west garden, but the project was abandoned when filling the lake caused flooding of the house's cellars. There are two further garden areas close to the site of the lake. These are the Pool Garden and the Heart Garden. These may have been the last areas with which Mawson was involved, and work ceased with the outbreak of World War 1.

Reginald Cory resumed work on the site after the war, but since World War 2 financial constraints have had an impact on the planting and maintenance of the site. Recent funding from the Heritage Lottery has enabled the restoration of the site to its Edwardian grandeur.