The Dderw is located a short distance to the north-west of Rhayader. It is a nineteenth-century house on a more ancient site (nprn 81174). It is surrounded by well-preserved wooded grounds and garden (86214), with associated parkland (700150). The former kitchen garden lies to the north-east of the house, conjoining the east wall of the pleasure garden area. 

The garden is a lozenge-shaped area, long axis north-east by south-west, about 1 acre (0.4 ha), and slopes to the south. Its date is uncertain. It is now mostly enclosed by fencing with only the north wall upstanding. It is partly occupied by a tree plantation, partly used for cultivating vegetables and some soft fruit, but traces of its historic use are still visible: a filled-in pool at centre; mature apple trees in the south-west corner, and nearby an abandoned summer house; to the rear of the garden are smashed Victorian lantern cloches; the brick footings of a lost glasshouse or bothy; abandoned brick cold frames; and a small lean-to glasshouse carrying the maker's mark of 'Walker's patent'.

The 1888 Ordnance Survey map portrays the garden with perimeter and cross paths with a pool at centre, and a small building on the outside north-west long wall. No glasshouses are shown. The garden went into decline afte the First World War.

Sources:
Cadw 1999: Register of Parks and Gardens of Special Historic Interest in Wales, Powys, 52-5 (ref: PGW (Po)2(POW)).
Ordnance Survey first-edition 25-inch map, sheet: Radnorshire XV.9 (1888).

RCAHMW, 11 May 2022