Schauhaus of the Grüningen Botanical Garden

The Grüningen Botanical Garden was founded in 1961 as a private garden. The ETH Zürich took over its management in 1976; since 1979 the Zürcher Kantonalbank (ZKB) has owned it and runs it through a foundation bearing the garden's name. In the garden's clearing, two greenhouses served both for raising plants and for display. The bank decided against simply repairing them, judging that unsustainable. The architects proposed separating the uses: a standard foil greenhouse at the back of the garden for propagation and, at the front, the money saved for a more generous show house.

The bank then held a competition with four participants. The young firm idA Buehrer Wuest, founded in 2010 by Stephan Buehrer and Martina Wuest, won the commission, with a budget of 1.5 million Swiss francs that forced repeated redesigns, notably to use economical glass sizes. The architects say they sent out about twenty-five tenders, of which only six came back, no steel-and-glass contractor wanting to take on the risk.

The two old greenhouses were demolished in 2012, the year the new Schauhaus was completed; Dezeen presented it on 3 September 2012. The building is listed among the winners in the public-buildings category of best architects 14, and the foundation's leaflet mentions several architecture awards.

The plan is inspired by cell tissue: the positions of the existing tree trunks and of the four steel "trees" serve as cell nuclei, and the Voronoi rule produces the roof outline. Each pillar combines twelve flat steel lamellas 40 mm thick; at about 5 m they branch into girders of varying inclination. A ring of flat steel joins the rib ends, fixes the polygonal outline and holds the glass walls at the top, which stand on strip foundations. In a recreation zone the maximum height of a single-storey building is 3.5 m; the municipality agreed to 5.5 m.

The glazing is the main difficulty. Baunetzwissen describes safety glass with a toughened outer pane of 15 mm, a laminated inner pane of 2 × 10 mm and a four-layer film in the cavity for UV transmission; Bauwelt speaks of triple glazing 5 cm thick and up to 5 m high, simply butt-jointed and held by U-profiles so that it can follow the movement of the steel. The architects allowed for gusts of 120 km/h. Seven vertical ventilation elements open automatically, triangular sun sails sit above the roof, rainwater runs down through the pillars and a printed plant motif protects birds.

The Schauhaus shows subtropical plants: papaya, banana, begonias, ferns and succulents, according to Baunetzwissen. The foundation's leaflet speaks of a collection of subtropical plants and succulents. Glass screens divide the space into planting areas, according to Dezeen. Plant propagation, formerly done in the old greenhouses, now takes place in the standard greenhouse at the back of the garden.

Around the building spreads a garden of 17,000 m², where sixteen sectors present plants from Switzerland and abroad: medicinal and culinary herbs, roses, ferns and a natural mixed forest. Many large trees give it the character of an arboretum, in which, the foundation says, the Schauhaus, modelled on a group of trees, blends in seamlessly.

The Schauhaus stands in the front part of the garden, among the trees, close to the entrance. It is visited together with the garden, open from April to October, with free admission. A free brochure, "Gartenrundgang", is available at the entrance for walking the sixteen sectors, and free one-hour guided tours take place on the first Sunday of each month at 11 am. Dogs must wait outside; the main paths can be used with a wheelchair.

According to the 2024 leaflet, the garden can be reached by bus (lines 867 from Wetzikon or 845 from Uster, stop Grüningen, Im Haufland, then a fifteen-minute walk). Lützelsee lake, 1.8 km away, and the town of Grüningen, with its castle and Reformed church, suit an extension of the day.