Tropical Greenhouse of the Bourgailh Ecosite

The Bourgailh site, on the western side of Pessac, took in a shared municipal landfill from 1981 to 1991. The buried waste formed an artificial hill, rising to almost 70 metres above sea level, inside a 110-hectare forest that has since been turned into a place for recreation, environmental education and botanical discovery.

The greenhouse exists thanks to a gift. Jean-Pierre Pelegry, a horticulturist by training, had spent more than forty years building up a private collection, begun with begonias and passion flowers and long kept in his own greenhouse at Cadaujac. In 2000 the town of Pessac took the collection in and installed it on the Bourgailh site.

The place also serves as a showcase for the reuse of the former tip. Substantial installations were built on the hill to capture the biogas released by the decomposing waste, and for five years they heated the greenhouse on an experimental basis. As the gas flow became too weak and too irregular, heating was handed over to a wood-fired boiler. Activities are run by the Écosite du Bourgailh association, whose programmes focus on the environment and sustainable development; in 2017 an exhibition on carnivorous plants was staged there in a new display.

The sources consulted say little about the building itself, and its designer is not recorded. The greenhouse covers about 1,300 m², a footprint borne out by the land-registry outline reproduced in OpenStreetMap. It forms a single undivided volume in which plants with very different needs grow side by side, from rainforest species to plants of arid habitats.

Its main technical interest lies in its heating. For five years it was warmed by biogas captured on the neighbouring hill and produced by the decomposition of waste buried in the former landfill. Falling and fluctuating gas output led to its replacement by a wood-fired boiler burning pellets from the forests of Nouvelle-Aquitaine.

The greenhouse is surrounded by teaching gardens, among them a demonstration vegetable plot cultivated from April to October. The wider site is also marked by three timber viewing towers: the tallest, at the main entrance, is 18 metres high and the two others 12 metres.

The collection numbers about 3,500 plants belonging to more than 1,000 species, which according to the town makes it the largest collection of tropical and subtropical plants in Nouvelle-Aquitaine. It bears its donor's stamp: begonias and passion flowers, with which it all started, along with orchids, bromeliads, carnivorous plants and Mexican cacti.

Succulents and agaves grow alongside baobabs, frangipanis and tillandsias, epiphytes native to the Americas. The specimens come notably from Africa, the Canary Islands, Central America and Australia. Themed exhibitions highlight plants adapted to extreme environments, and a "Who am I?" game invites visitors to explore the relationships between plants and animals.

The greenhouse stands in the Bourgailh forest, on the avenue de Beutre on the western side of Pessac, and a stop on the TBM bus network is named after the forest. It opens seasonally, from mid-April to mid-October, and then closes so that the collections can be maintained. Guided tours give visitors the chance to smell and touch some of the plants. The forest walks, free and open all year, can be extended by climbing the viewing towers or by following a 1.3-kilometre interpretation trail that links the forest with the neighbouring zoo.