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Do you know which species or cultivar of Gardenia you are growing? Nevertheless the culture for most will be similar: full to part sun, regular water, well-draining, acidic soil, fertilize occasionally with an acidic fertilizer.
Gardenia is large genus of evergreen shrubs and small trees in the Madder Family (Rubiaceae). The genus is native to tropical Africa, Madagascar, tropical Asia, Sri Lanka, Japan, Hainan, Taiwan, Japan, Philippines, Indonesia, New Guinea, Australia, Vanuatu, Solomon Islands, Fiji, New Caledonia, and Hawaii. A number of species are cultivated in warm temperate and tropical regions for their white to yellow, fragrant blossoms. Popular species include Hawaiian Gardenia (G. brighamii), Common Gardenia (G. jasminoides), and African Gardenia (G. thunbergia).