Tropical Montane Orchidetum (Cool House)

The Tropical Montane Orchidetum is the newest extension of the National Orchid Garden, the orchid showcase of the Singapore Botanic Gardens, which opened in October 1995 on the highest hill in the Gardens. Orchids have long been bound up with the institution's history: under director Eric Holttum (1925-1949) the Gardens pioneered the orchid hybridisation programme that made its name, and the hybrid Vanda Miss Joaquim became Singapore's national flower in 1981.

The Orchidetum was part of a wider expansion of this part of the Gardens that opened in stages from 2019, beginning with the Mingxin Foundation Rambler's Ridge and the OCBC Arboretum. Prime Minister Lee Hsien Loong officially opened it on 3 April 2021. Its centrepiece, the Sembcorp Cool House, is an enlarged and upgraded successor to the Gardens' original Cool House, made possible by sponsorship from Sembcorp Industries. The work also brought a refurbished Tan Hoon Siang Mist House. According to the Gardens' magazine Gardenwise, the project added about 5,000 m² of display space and more than doubled the orchid collection on show. The Singapore Botanic Gardens have been a UNESCO World Heritage Site since 2015.

The Orchidetum is laid out as a climb through the vegetation belts of tropical mountains. The route begins outdoors on the Lowland Habitat Trail, devoted to lowland forest, then drops into the Secret Ravine, a meandering path modelled on deep mountain valleys. Two display houses stand for the middle elevations, the Yuen-Peng McNeice Bromeliad Collection and the Tan Hoon Siang Mist House, before the Sembcorp Cool House represents the high montane zone.

The Cool House covers about 1,100 m². To keep the energy demand of a chilled glasshouse at the equator in check, it combines spectrally selective glazing that cuts heat gain, a high-efficiency cooling system and solar panels that offset part of its consumption. Inside, the planting is arranged into five biogeographical regions: Malesia, continental Southeast Asia and South Asia, Australasia, the Afrotropics and the Neotropics.

The Sembcorp Cool House displays more than 1,000 species and hybrids of cool-growing orchids, accompanied by around a hundred species of herbaceous plants. Montane orchids on show include slipper orchids (Paphiopedilum), Dendrobium, Phalaenopsis and Angraecum, set among rhododendrons. The house also holds a Wollemi pine (Wollemia nobilis), a gift from Australia in 2015; the species was known only from fossils until its discovery in 1994.

Further down the route, the Tan Hoon Siang Mist House pairs award-winning orchids with begonias and aroids, while the bromeliad collection ranges from pineapples to Neoregelia and Guzmania. The Lowland Habitat Trail highlights epiphytic lowland orchids, including Vanda Miss Joaquim and its parent species, as well as Renanthera hybrids.

The Orchidetum lies within the National Orchid Garden, a ticketed section in the central part of the Singapore Botanic Gardens. The route is best followed in order of altitude, from the lowland trails up to the Cool House, whose chill contrasts sharply with the tropical air outside. It combines naturally with the rest of the orchid garden, including the Orchidarium, and with the collections and rainforest of the Botanic Gardens, itself a World Heritage Site.