Penrhyn Castle, an early nineteenth-century neo-Norman castle (nprn 16687), is located on the Menai Strait, to the north of Llandegai. It lies centrally within a roughly circular landscape park (700208) and is surrounded by well-preserved gardens laid out during the nineteenth century by the Pennant family (86440).
The walled flower garden lies about 230m to the west of the house on a fairly steep, south-west-facing slope surrounded by woodland. It was laid out in the second half of the nineteenth century and replaced, on a favoured site, a smaller kitchen garden of the eighteenth century, relocated elsewhere (700209).

The plan is rectangular, long axis north-west by south-east, the south-west long side bowed out slightly. The enclosing brick walls probably belong to its early nineteenth-century predecessor. The north and east corners are rounded. The formal, ornamental, layout is terraced on three levels, the terraces retained by stone walls. The bog garden, below the lower terrace, is a later enlargement, and possibly explains the removal of south-west boundary wall. There were also some twentieth-century alterations.

The narrow topmost level is formal with three pools, regular beds and a central loggia which replaced a conservatory. There are several entrances, the main one via an iron gate near the east corner. The middle terrace is a wide, sloping lawn planted with trees and shrubs and with gravel paths dividing it into quadrants. There are borders down each side and under the retaining wall of the top terrace. Of a range of potting sheds built against the outside north-west wall, only the footings remain. There are steps from the upper to the lower terrace at either end and in the centre, with paths leading straight downwards from each flight. Steps to the bog garden lead down through the centre of the lower retaining wall. An iron pergola, clothed in Fuchsia, runs over the walk along the top of the lower retaining wall but was originally set over the central path. The lowest garden level is the bog garden, a damp level area, marshy at the north-west end. Planting is informal, with trees and damp-loving species set in roughly-mown grass, though it was once more densely planted.

Sources:
Cadw 1998: Register of Parks and Gardens of Special Historic Interest in Wales: Conwy, Gwynedd & the Isle of Anglesey, 250-7 (ref: PGW(Gd)40(GWY)).
Ordnance Survey Second Edition 25-inch map, sheet: Caernarvonshire VII.9 (1900).

RCAHMW, 26 May 2022