Few plants earn their spot the way a gardenia does. The foliage is deep green and glossy twelve months of the year, and from spring through autumn the shrub covers itself in creamy white blooms with a perfume strong enough to drift through open windows. In warm parts of Australia, from Sydney and Perth up through Brisbane and the tropics, gardenias have been a front path and courtyard staple for generations.
They also carry a reputation for being fussy, which is only half deserved. A gardenia with acidic soil, morning sun and a regular feed is a remarkably easy shrub. A gardenia in alkaline soil next to a concrete slab is a slow-motion sulk. Get the fundamentals right at planting time and most of the classic gardenia complaints, yellow leaves included, simply never turn up.
Quick facts
| Botanical name | Gardenia augusta (syn. Gardenia jasminoides) |
| Type | Evergreen flowering shrub |
| Height | 30cm to 2m depending on variety |
| Position | Morning sun or full sun with afternoon protection in hot districts |
| Soil | Rich, acidic and free draining, pH 5 to 6.5 |
| Flowers | White, heavily perfumed, spring to autumn |
| Climate | Warm temperate, subtropical and tropical; frost tender |
Choosing the right gardenia
For hedges and mass planting
The workhorse of Australian gardens is Florida Gardenia, a neat 1m x 1m shrub that flowers for months and clips into a beautiful low, perfumed hedge, available from $10.95. Where you want more height, Magnifica Gardenia reaches 1.5m to 2m with larger, fuller blooms and makes a generous informal screen or backdrop shrub.
For pots, borders and small spaces
Radicans Gardenia is the groundcover of the family, staying around 30cm tall while spreading to a metre, which makes it ideal for spilling over retaining walls, edging paths or filling pots. If flower size is the goal, Aimee Yoshiba Fragrant Gardenia carries the largest blooms of any variety we sell, big ivory flowers that open flat like saucers, also from $10.95.
For trickier climates and native gardens
Star Gardenia bears single, star-shaped flowers and is noticeably tougher than the augusta types, handling cooler nights and less pampered soil. For native gardens, Native Gardenia (Randia fitzalanii) is a glossy rainforest tree to around 5m with sweetly scented white flowers followed by yellow fruit, a lovely small shade tree for frost free areas.
Planting
Plant in spring or autumn in a spot with morning sun and shelter from scorching afternoon summer sun; in mild coastal areas full sun is fine. Soil is where gardenias are won or lost. They need acidic conditions, so dig through compost and a camellia and azalea planting mix, and avoid planting hard against new concrete paths or rendered walls, which leach lime and push the pH up. Space Florida at 50cm to 75cm for a hedge, Magnifica at around 1m, and Radicans at 60cm for groundcover. Water in thoroughly with a seaweed solution and mulch 5cm deep, keeping mulch clear of the stem. In pots, choose a container at least 40cm wide with a premium azalea and camellia mix, and lift it on pot feet so the drainage holes stay clear.
Ongoing care
Watering: Deep soak once or twice a week through the warm months rather than a daily sprinkle. Gardenias resent drying out while in bud, and pots may need watering every second day in summer.
Feeding: Feed in early spring and again in late summer with a camellia and azalea fertiliser. A teaspoon of Epsom salts dissolved in a watering can every couple of months keeps magnesium up and foliage deep green. Liquid feed potted gardenias monthly through the growing season, since nutrients leach faster from containers.
Pruning: Trim lightly after the main flush of flowers to keep plants dense. Avoid hard pruning in autumn, since you will be cutting off the wood that carries next season's buds.
Common problems
Yellow leaves in winter: The most Googled gardenia problem in Australia, and usually the least serious. Cold soil stops magnesium uptake, older leaves yellow and drop, and the plant greens up again in spring. Epsom salts and patience fix it.
Yellow leaves with green veins in summer: That pattern is iron deficiency caused by alkaline soil. Apply iron chelates and acidify with a camellia and azalea fertiliser.
Bud drop: Buds forming then falling before opening comes down to irregular watering or sudden temperature swings. Mulch well and keep moisture consistent.
Aphids, scale and sooty mould: Black film on leaves means sap suckers are working above. Treat the insects with horticultural oil and the sooty mould washes away on its own.
Frequently asked questions
How fast do gardenias grow?
Gardenias are moderate growers. Expect a Florida gardenia to reach its full 1m in around three to four years, faster in warm climates with regular feeding.
Do gardenias grow well in pots?
Very well, and pots are the best option in cool climates or on alkaline soils. Use a premium azalea and camellia potting mix, a pot at least 40cm wide, and feed a little more often than you would in the ground.
Are gardenias frost tolerant?
Not really. Light frost will burn foliage and buds. In frost prone areas grow Star Gardenia, which is the toughest of the group, or keep plants in pots that can shift under cover in winter.
Why is my gardenia not flowering?
Usually too much shade or a nitrogen heavy lawn fertiliser drifting into the bed, which grows leaves at the expense of buds. Give it at least four hours of sun and switch to a camellia and azalea food.
Ready to plant?
Browse our full range of flowering plants and shrubs to pair gardenias with their favourite companions, or check our pot and bag size guide to see exactly what arrives at your door. Every order is covered by our 30 day satisfaction guarantee.
