Updated: Dec 30, 2021
The Gardenia is native to the Far East from India through to Japan. Its creamy white double flowers are fragrant and mat textured. In India and other Eastern Asian countries, Gardenia necklaces are offered to local divinities and tied to maidens hair. Gardenia jasminoides is a small shrub with greyish bark and dark green shiny leaves.
Gardenia Bonsai create a dense medium to large bonsai in almost all styles, but they are most popular as informal upright and broom styles. In these styles, the crown is allowed to volumise, allowing the dazzling white flowers to show off.
Position: They are best grown indoors in a warm conservatory or heated greenhouse in temperate zones. They need a lot of light and humidity, so situate in a bright spot but avoid exposure to direct midday sunlight if possible. If required, provide additional artificial lighting during long winter nights. Use a humidity tray to provide the high levels of humidity it needs, and ensure temperatures are above well 15°C every day. Ensure there are not-too-much temperature fluctuations.
Watering: Gardenia Bonsai like moist, but not waterlogged soil. Water early in the morning to ensure the bonsai has enough when it needs it during the day and can use it up before nightfall. Overwatering and waterlogging can lead to chlorosis, turning leaves yellow and falling off.
Feeding: Fertilise every two weeks during the growing season and six weeks during dormant periods. Use a balanced organic fertiliser throughout the year and use an additional dose or two of high nitrogen fertiliser in spring to help flush new growth. They love acidic soil so use an organic soil acidifier or teaspoon of vinegar to help keep the pH low and prevent chlorosis.
Repotting: Repot every two years in late spring when the warmer weather is well settled. Use a rich, well-draining soil of peat or loam, grit or sharp sand, leaf mould or bark in equal parts by volume. Conversely, you can use a mixture of Akadama, Pumice and well-mulched bark in equal parts.
Pruning: Gardenia set their buds late summer in July for the next season; it is best to prune after flowering. Cut back fully extended shoots to leave three active leaf nodes. Structural pruning is best carried out at this time, as this will effectively eradicate most or all the flowering buds.
Wiring: Gardenia is best styled with the clip and grow method. It is best wired in autumn when the bonsai is dormant if wiring is required.
Propagation: The easiest way to propagate Gardenia is with Softwood cuttings, in late spring to autumn to mid-summer. Semi-hardwood cuttings have a lesser success rate. In addition, gardenias cutting need bottom heat above 18°C, and for better results, use a rooting hormone.