Richardson Glasshouse and Temperate House, Johnstown Castle walled garden

The walled garden at Johnstown Castle was laid out between 1844 and 1851, according to the Irish Heritage Trust and Teagasc; the National Inventory of Architectural Heritage (NIAH) dates its walls to 1844 and notes that the garden already existed by 1852. The Trust credits the layout to the landscape designer Daniel Robertson, who is also linked to the gardens at Powerscourt and Wells House, and states that the walls are now the only original feature.

The glasshouse is later than the garden. The NIAH record, based on a survey of July 2009, dates the 33-bay lean-to to between 1865 and 1903 and records it as standing in 1903; it quotes an 1852 description of a grand circular conservatory flanked by long graperies, which the present glasshouse is said to succeed. The estate now gives its glasshouses the label 'Richardson'.

In 2009 the glasshouse was disused and its interior in ruins. The Irish Heritage Trust, appointed by Teagasc to run the estate, which opened to the public in 2019, began a three-year renewal of the walled garden and glasshouses in 2020. In March 2023 the walled garden was still closed for the last stage of the glasshouse works; in June 2023 the press announced the opening of the central Temperate House, with the rest to follow in phases once the flagstone floor was finished, and a smaller glasshouse in the yard was to be conserved next. In October 2024 the head gardener gave a talk on the history of the glasshouse and its restoration, and a photograph of August 2026 shows the long glazed range, painted white.

The main glasshouse is a lean-to: a long glazed range built against a wall of the walled garden. The Irish Heritage Trust gives its length as 50 metres; in its description of 2009, before the works, the NIAH counts 33 bays arranged symmetrically around a single-bay, gabled, glazed porch. The glazed lean-to roof is centred on the glazed gabled roof of the porch; the walls are rendered and lined, the timber-mullioned windows hold fixed panes with vertical glazing bars, and the central glazed door, with sidelights, is approached by two granite steps. The Trust speaks of a Temperate House at the centre and of a 'unique vent' conserved with it.

The floor is flagged, and its restoration formed part of the works. A second, smaller glasshouse stands in the yard, which the estate also calls a Richardson glasshouse. The 4-acre walled garden around them is enclosed by coursed rubble walls with rounded coping; on the courtyard faces, red brick is laid in English garden wall bond, according to the NIAH.

The smaller glasshouse in the yard is meant for propagating plants raised from seed in the large one, and for gardening demonstrations and events. The head gardener states that everything grown on the estate is propagated on site, from seed or cuttings.

In the walled garden the team has replanted a herbaceous border of 3,000 plants raised in peat-free compost, which flowered as a new display for the first time in 2023, together with prairie-style planting and meadow areas. Elsewhere on the estate an edible woodland holds 85 heritage apple trees and cobnut trees, and the blueberry bushes are said to be the oldest in Ireland.

The glasshouse stands in the walled garden, which the estate describes as wheelchair accessible. General admission covers the gardens and the Irish Agricultural Museum, and the estate is open throughout the year apart from a few days around Christmas.

The walled garden combines easily with the rest of the 120-acre estate: the sunken garden, lakeside walks (22 acres of water), a 15-acre arboretum, and the guided tour of the neo-Gothic castle, for which pre-booking is recommended. According to the Irish Heritage Trust, the estate is ten minutes from Wexford town.