Pregny Greenhouses (reserve glasshouses of the Geneva Conservatoire and Botanical Garden)

From 1860 Baroness Julie de Rothschild had several greenhouses built outside the grounds of the Château de Pregny, on the far side of the Route de Pregny. She laid out areas for grapes, peaches and figs, and for ornament, with orchids, tropical plants and palms. The oldest, from the 1860s, takes the form of a long corridor. The complex took shape from the 1880s; according to the architectural survey of the canton of Geneva (2023), its execution can be partly credited to Robert Halliday, an English architect who specialised in greenhouses. Beyond production, the complex was designed as a place for the family and its distinguished guests to stroll. A 2020 leaflet of guided tours, by contrast, mentions the "famous architect Paxton".

The Rothschild family later handed the greenhouses over to the State of Geneva; they now belong to the Republic and Canton of Geneva and are used by the Conservatoire and Botanical Garden (CJB). In the 1960s the demolition of a neighbouring greenhouse, followed thirty years later by a clumsy intervention, hastened the decay of the timber. A painstaking restoration has been under way since 2017: greenhouse 02 has regained its former appearance, greenhouse 08 shows its rafters and the north-east gable has been preserved. According to the municipality, the City of Geneva renovated and rehabilitated the complex. Wikidata lists it in the Swiss inventory of cultural property as an object of regional importance (class B, number 11823).

The greenhouses are built of Canadian pitch pine. Their glass panels are set into a metal or timber structure whose layout varies with the needs of the plants grown. The complex is made up of several numbered units, among them greenhouses 02 and 08, named in the restoration programme. The oldest, from the 1860s, forms a long corridor softened by the arches of its supports; its heated, paved floor is made of openwork cast-iron panels decorated with oriental-style rosettes. The elegant glass buildings can be seen from the roadside on the Route de Pregny.

The architectural survey of the canton puts the complex at 10,523 m². The restoration concerns above all the timber frame, weakened by the demolition of a neighbouring greenhouse in the 1960s and by a later intervention. The 2025 heritage-days tour was led by an architect, an engineer and a scientific officer of the Ville de Genève's architectural heritage conservation unit; no other technical data (dimensions of each house, type of glass) could be found.

Since the Botanical Garden took them over, the Pregny greenhouses have served as a reserve. Le Temps compares them to a museum's storerooms: they hold the rare specimens or those hard to display, chiefly exotic and tropical plants that do not normally grow in Switzerland. Official programmes mention collections of succulents, palms and citrus.

In the Rothschild era the crops included vines, peach trees, fig trees, orchids, tropical plants and palms; the baroness showed her rare plants there, orchids among them. A visit offered by the CJB in December 2020 focused on the scents of flowers and leaves in the "exceptional collection of the Pregny greenhouses".

Unlike the Botanical Garden, which is designed to receive the public, the Pregny greenhouses are not set up for visitors and open only on organised visits. The sources document three: guided visits in the CJB programme in December 2020, three one-hour slots during the European Heritage Days on 14 September 2025, and a free guided tour led by the gardeners on Wednesday 4 November 2026, open from age 10, with online registration (shown as full when consulted).

It is therefore necessary to check with the Botanical Garden before travelling. The greenhouses can also be seen from the outside, from the Route de Pregny, and a visit combines naturally with the nearby Botanical Garden, whose publicly open glasshouses have a separate entry.