Plas Dinam, a late nineteenth-century house dating from about 1873 (nprn 29811) on the north side of Llandinam village, is set on a rise in the Severn Valley, looking south towards Llanidloes. It is noted for the arboricultural interest of its garden which, together with the house, occupy a fine valley setting.
The gardens and grounds cover about five acres and lie mainly to the north and south of the house on ground which rises up to the east. An additional area of approximately 10 acres (2ha) lies beyond this, two pasture paddocks extending to the upper lane to the north, and south to the village.

The only obvious example of ornamental planting is in the south of the north paddock where a small circular stand of acers is surrounded by iron fencing. Formal gardens were made and tree planting was carried out around the house as soon as it was built. The form of the garden area is much as it was in 1884 when the Ordnance Survey map shows walled terraces to the north-west, south-west and south of the house. Changes have occurred since then, with the grounds once having had a more ‘park-like’ and wooded chraracter, but it declined and became simplified with reductions in the number of garden staff.

The grounds are approached by a long drive, which runs up from an entrance and lodge off the east side of the A470 road, onto a wide rectangular gravelled forecourt running the length of the north front of the house, the ground rising to the south towards the house. To the north of the house the garden takes the form of a tree planted lawn, sweeping down to the drive, and beyond for about 4m, to the garden boundary. On the lawn mature plantings include cedar, cypress and chestnut. To the east the garden terrace along the Ty'n-y-maen lane is bounded by trees, laurel and rhododendron, and a small vegetable garden has been created at it south end.
To the west of the house is a partly-walled rectangular formal garden, and on the south a large, partly-walled lawn. To the west of the latter is a hard tennis court which lies at the edge of a narrow strip of woodland of native and exotic trees flanking the south paddock and extending north to the drive entrance and south to the village. A yard to the north of the tennis court contains two free-standing single-aisled greenhouses and at least two sets of cold frames, mostly derelict.

At some point after 1900 the north garden boundary was extended to incorporate the drive and the area east of it which was planted up as a Japanese Wood. Since 1903 the woodland along the south path has also gradually extended to run the entire length. Between about 1940-1956 the gardens were affected through the change of use of the site. Part of the Japanese Wood was cleared and a level terrace created for a school and Land Army buildings and trees were removed from the south garden creating an open view to the south. Further declines occurred in the post-War period.

Sources:
Cadw 1999: Register of Parks and Gardens of Special Historic Interest in Wales, Powys, 202-5 (ref: PGW (Po)25(POW)).
Ordnance Survey first-edition 25-inch map, sheet: Montgomery XLII.7 (1886).
RCAHMW air photos: 94-CS 0514; 945070/50.

RCAHMW, 29 June 2022