Palmenhaus (Palm House), Mainau Island

The story of Mainau's glasshouses begins with Grand Duke Frederick I of Baden, who bought the island in 1853 as his summer residence. From 1856 his head gardener Ludwig Eberling built up collections of Mediterranean and exotic plants, an arboretum and an Italian rose garden. To overwinter palms and citrus, the court set up the first winter shelters, including a demountable heated orangery in 1867. The Canary date palm that now dominates the palm house was planted in 1888.

The island passed to the Swedish royal family in 1928. In 1932 Prince Wilhelm of Sweden handed its management to his 23-year-old son Lennart Bernadotte, who took over a park overgrown with vegetation and gradually turned it into a flower island. In 1968 a large palm house replaced the old winter shelters; thirty years later, in 1998, the building was completely renewed.

Mainau GmbH, the company that runs the island, is 99 per cent owned by the Lennart Bernadotte Foundation, set up in 1974. In 2003 the palace core and a quarter of the island were declared a cultural monument of special importance by the regional administration in Freiburg.

The present palm house, the result of the complete renewal of 1998, covers 1,270 m² and rises to 17.40 m. Its envelope is made of highly transparent acrylic sheets six millimetres thick, and its wave-shaped roof gives it a silhouette recognisable from afar, far removed from the iron-and-glass houses of the nineteenth century. The sources consulted name neither the architect of the 1968 building nor that of 1998.

The island has a second large glasshouse, the butterfly house, opened at the beginning of 2000. Covering about 1,000 m², it is described as the second largest of its kind in Germany. It is kept at 25 to 30 °C with 80 to 90 per cent humidity, the conditions needed by the tropical butterflies that fly freely among its plants.

The palm house holds more than twenty palm species as well as orange trees. Its centrepiece is a Canary date palm (Phoenix canariensis) planted in 1888, now more than 15 m tall and thus a survivor from the grand-ducal era of the collections.

The building is also the setting for the island's major flower shows. From mid-March to early May the orchid show presents more than 3,000 plants, continuing an orchid display that Mainau already offered in 1955; in September and October an autumn exhibition takes over, devoted in 2026 to exotic fruits. In the butterfly house, 700 to 1,000 butterflies of up to 80 species are on the wing at any time; about 400 pupae are delivered each week from Costa Rica, England and the Netherlands.

The palm house stands at the heart of the island, a few dozen metres from the baroque church and palace built in 1739-1746 for the Teutonic Order. It opens every day, and a visit fits naturally into a circuit of the island, between the arboretum, the Italian rose garden and the butterfly house.

Spring, with the orchid show and the flowering of the park, and early autumn, with the seasonal exhibition set up beneath the palms, are the times when the building is at its liveliest. A full day allows the island to be explored without hurry.