Castell Malgwyn (nprn 21729) and its grounds are located in parkland (700183) on the south bank of the river Teifi, just south of the village of Llechryd. 

The grounds represent the survival, almost in their entirety, of intricate and highly picturesque landscaping created by Sir Benjamin Hammet in the period 1791–1811. Some work was carried out on the grounds by one of the few Welsh professional landscapers of the period, Charles Price of Llechryd. The setting is one of extreme beauty and picturesqueness, with the contrasting valleys of the Teifi & Morgenau (between which the house lies) incorporated in the scheme. The picturesque walks laid out in the valleys are a rare survival and can be compared with Piercefield (Monmouthshire) & Hafod (Ceredigion).

The garden and pleasure grounds associated with the house divide into distinct areas. First, there is the main garden next to the house. Secondly there are the woodland pleasure grounds further away, of a different character (700185). Then there are garden areas on the far side of the park close to the model farm (265250; 700186).
The main garden lies to the east and south of the house. To the east the ground falls towards the Morgenau valley; to the south it rises gently towards a plateau between the two valleys. On the east, there is a large croquet lawn cut into the slope with a small wooden pavilion at its south end. At the north end is the drive and a bank of mixed trees and shrubs, dominated by mature beech underplanted with ornamental shrubs. From the forecourt a section of drive curves around the south end of the croquet lawn, backed by a low drystone wall. The southern boundary of the lawn to the south, and of the lawn south of the house, is planted with a belt of mixed ornamental trees and shrubs, including conifers.

On the south side of the house there is a large lawn bounded by trees and shrubs, the lower part levelled and originally a tennis lawn. Above this the ground slopes up to the belt of trees, fringed with rhododendrons, azaleas and a large, multi-stemmed cypress. A modern swimming pool (1969/70) lies close to the house on the north-west. Just south of the pool a path leads south-westwards across the lawn, through the shrubs and into the woodland area flanking the Teifi.

Sources:
Cadw 2002: Register of Parks and Gardens of Special Historic Interest in Wales, Carmarthenshire, Ceredigion and Pembrokeshire, 172-8 (ref: PGW(Dy)32(PEM)).
Ordnance Survey second-edition six-inch map, sheet Cardiganshire XXXVIII.SW (1904).
Additional notes: D.K.Leighton.