Pflanzenhaus (Cactus House) of the Villengärten

The story of the Pflanzenhaus begins in Überlingen's Stadtgarten, a public garden laid out from 1875 on former vineyards and market gardens west of the old town, for spa and bathing guests. Hermann Hoch (1866-1955), the first town gardener, in post from 1894 to 1931 according to the tourist office, laid the foundations of the cactus collection: German Wikipedia dates his first cactus bed to 1897, whereas the caption of a photograph uploaded to the LandApp BW app speaks of a collection founded in 1905. The collection stayed in the Stadtgarten for more than 125 years, according to the tourist office. The plants were taken outdoors there in spring, after the Ice Saints, and brought back in before the first frosts, a move known as "Kakteenwandern" and repeated twice a year until 2021. According to the builder of the glasshouse, the operation cost 45,000 euros a year, the plants spent about seven months in a greenhouse closed to the public and transport damaged them.

The Baden-Württemberg Landesgartenschau, planned for 23 April to 18 October 2020, was put back a year because of the pandemic and ran from 30 April to 17 October 2021. The Pflanzenhaus was built for it by EdenParks and Smiemans Projecten (completed 2021-2022 according to the builder), in the Villengärten area close to the shore. During the show the state used it for its "Treffpunkt Baden-Württemberg". The house was then meant to shelter the municipal collection for good: the plants moved in in early summer 2022, according to the tourist office, and the glasshouse has been open all year since.

The tourist office describes the building as a large glass structure; German Wikipedia gives it a height of almost ten metres and a footprint of 600 m², of which about 250 m² are planted beds, the latter figure also being the town's. The builder classes it among its arched "HighLight" greenhouses, delivered turnkey: EdenParks, part of Smiemans Projecten, produced the design and Smiemans Projecten carried out the construction.

The brief explains the plan. The building was conceived for two successive uses: a meeting place and pavilion during the Landesgartenschau, then a permanent home for plants that cannot withstand frost and no longer go outdoors in summer. The beds group the plants by geographic origin. Above the technical and service rooms the builder created a visitor area that gives a good view of the collection.

The town reports about 1,000 cacti and succulents on show, some of them more than 100 years old. The largest specimens reach seven metres in height according to the town's page and the tourist office's; the weights quoted vary, from 250 kg for plants over six metres tall (Stadtgarten page) to about 300 kg (Kakteenhaus page). The plants are grouped by geographic origin across some 250 m² of beds. The town calls them "exotic".

The caption of a photograph uploaded to the LandApp BW app mentions about 5,000 cacti for the whole Überlingen collection, a figure the town's own pages do not repeat. Only the hardy specimens stay outdoors, in the cactus bed of the Stadtgarten, which can be seen all year. Guided tours offered every week with local guides explain which plant families occupy which beds.

The Pflanzenhaus stands at the entrance to the Villengärten, on the Bahnhofstraße side, west of the old town. This lakeside park, listed as accessible to wheelchair users, hosted thirteen show gardens, floating gardens and an open-air library in 2021; it also has a Kneipp basin, a listed bathing pavilion (Badehäuschen) from before 1900 and a shoreline path leading to the Bodensee-Therme. The Stadtgarten of 1875, with its bed of hardy cacti, is close by, as are the Badgarten and the Rosengarten, and these gardens appear on the town's Gartenkulturpfad. As the plants no longer go outdoors in summer, the collection can be seen in every season.