The Wahiawa Botanical Garden, 27 acres (11 ha) is a botanical garden on a high plateau in central Oʻahu, Hawaiʻi, United States, located between the Wai'anae and Ko'olau mountain ranges. It is one of the Honolulu Botanical Gardens, and home to a collection of tropical flora requiring a relatively cool environment, with emphasis on native Hawaiian plants. It is nicknamed the "tropical jewel" of the Botanical Gardens. The Garden's site began in the 1920s, when the Hawaiian Sugar Planters' Association leased land from the State of Hawaiʻi for experimental tree planting. Most of the Garden's large trees date from that era. The property was transferred to Honolulu in 1950, and opened as a botanical garden in 1957. It is open seven days a week, from 9am to 4 pm.