The Penllergaer estate is an important picturesque and romantic river valley landscape of the mid nineteenth century (nprn 232123), created by John Dillwyn Llewelyn (1810-1882). Although there has been much development (Penllergaer House has now gone) the structure of his landscaping survives, and an important feature of this is the walled garden. It is probably contemporary with the house and grounds, dating to the 1830s, and Llewelyn. It was certainly in place by 1840, when it appears on the tithe map. Although now ruinous it seems to have kept its original layout and most of the features shown on the 1876 Ordnance Survey map can be located.

The complex lies on the west side of the valley, to the south of the house site. To its north and east there is a steep drop to the south drive; to the south and west are housing and related developments. There are several components to the gardens, the main one of which is a large, walled, trapezoidal garden, long axis north by south, wider on the south and narrower on the north. It is bounded by high stone walls 3.5m-4m high. It contains the remains of a glasshouse and other buildings. Perimeter and cross path lines can be made out by their edging kerb stones. In the centre is the overgrown stone surround of a former small pool. To the immediate south of the main area were other glasshouses and building ranges, and to the north-west another pool and glasshouse. In all there were up to a dozen hothouses but only fragmentary remains of these, and of other buildings, survive.
Detailed study of the site (GGAT) has identified the smaller walled compartments outside the main garden as a melon ground, heather house, rock garden, pineapple house, and the ruined buildings of gardener’s accommodation.

The most important feature of this area is the orchideous house (19644). Located in the main area, its very overgrown remains lie just to the north-east of the central pool. It was built in two phases. First, an ordinary orchid house was built in the early 1830s (it was referred to in 1835). Then the house was turned into an epiphyte house for non-terrestrial orchids in 1843 by the addition of a hot water fall over rockwork. The house achieved the distinction of being described in the first issue (1846) of the Journal of the Horticultural Society.

Sources:
Cadw. 2013. Register of Parks and Gardens of Special Historic Interest in Wales: (ref: PGW(Gm)54(SWA)).
GGAT: Glamorgan Gwent Archaeological Trust Historic Environment Record.
Ordnance Survey first-edition six-inch map, sheet: XIV (1884). 

RCAHMW, 25 July 2022