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Gardenia thunbergia /θʌnˈbɜːrdʒiə/

Common name: White gardenia · Forest gardenia · Wild gardenia

Gardenia thunbergia is an evergreen shrub or small tree in the coffee family Rubiaceae, native to southern and eastern Africa, including South Africa. It typically reaches 2–5 m in height, with glossy dark green leaves clustered at the branch tips and large, fragrant white flowers that open mainly at night. It is widely cultivated in warm climates as an ornamental, valued for its elegant blooms, glossy foliage, and decorative woody seed capsules.

Care summary

Sun Full sun to partial shade
Water Regular water; moderately drought tolerant once established
Soil Slightly acidic, fertile, well-drained
Hardiness Zones 9–11
Mature height About 200–500 cm (6.5–16 ft)
Pet safe No — gardenias are mildly toxic to cats and dogs
Difficulty Moderate
Propagation Propagate by semi-hardwood cuttings or from seed. Take 10-15 cm cuttings, remove the lower leaves, treat with rooting hormone, and root in a warm, humid, well-drained medium. Fresh seed can also be sown in spring, though seedlings are slow to flower.

Fun facts

  • Its night-scented white flowers are adapted for pollination by moths.
  • The hard, woody seed capsules can persist on the plant for years and are used in floral arrangements.
  • The species honors Swedish botanist Carl Peter Thunberg, who collected plants in South Africa in the 18th century.
  • It is the parent species from which many horticultural gardenia stock plants are grafted, as its roots resist nematodes.

Common problems

    • Feed with an acid-loving plant fertilizer
    • Apply chelated iron to the soil
    • Water with rainwater, not hard tap
    • Keep night temperatures cool and steady
    • Avoid moving budded plants around
    • Keep soil evenly moist, never dry
    • Treat the underlying pest infestation first
    • Wipe mold off leaves gently
    • Spray pests with horticultural oil
    • Give bright light with gentle morning sun
    • Feed with high-potash fertilizer in summer