Gardenias: How to Grow Fragrant, Flowering Gardenias in Australian Gardens & Pots

Gardenias (Gardenia jasminoides) are iconic evergreen shrubs known for their lush, glossy leaves and beautifully fragrant white blooms. Native to tropical and subtropical Asia, they thrive in Australia’s temperate to warm climates with the right care. This guide covers how to grow gardenias successfully in the ground or pots, how to prune and maintain them, and which CompleteGrow fertilisers produce the best flowering results.

Gardenia Growth Habits & Care Requirements

Gardenias can be grown as standalone shrubs, hedges, or container plants. They’re prized for their intense fragrance, especially in the evening, and flower prolifically through late spring to early summer.

Height & Spread: Most varieties grow 1–2 m tall with a rounded habit
Light: Full sun to part shade (morning sun preferred; protect from harsh afternoon rays)
Soil: Slightly acidic (pH 5.0–6.5), free-draining and nutrient-rich
Water: Regular moisture — gardenias dislike drying out but hate waterlogging
Climate: Best suited to warm temperate, subtropical and tropical regions

Common Gardenia Problems:

Yellowing leaves (chlorosis) from poor drainage or iron/magnesium deficiency
No flowering due to excess nitrogen or poor pruning
Buds dropping before blooming due to temperature swings or moisture stress

Gardenias in Pots: Container Growing & Soil Setup

Growing gardenias in pots is ideal for controlling soil pH and drainage — and it lets you move plants to sunnier or more sheltered spots throughout the year.

Potting Guidelines:

Use a wide, deep pot (35+ cm) with drainage holes
Fill with acidic potting mix or a blend of premium potting mix with added perlite
Top-dress with bark or coconut fibre to retain moisture and suppress weeds
Keep pot raised to ensure proper air flow and drainage beneath

Gardenias in pots dry out faster than those in garden beds — water as soon as the top 2–3 cm of soil feels dry, especially during flower-bud development.

Soil Fertilisation Tip:

To prepare the soil before planting or repotting, water in with a half-strength mix of our all-purpose balanced fertiliser:

CompleteGrow NPK 20-20-20 Liquid Fertiliser – Ensures initial nutrient availability and root stimulation for transplant success

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Best Fertiliser for Gardenias: Flowering, Leaf Health & Soil Nutrition

Gardenias require consistent feeding with a formula rich in magnesium, iron, and potassium to promote flowering and prevent common issues like yellowing leaves (chlorosis). Balanced nutrition supports bud development and deep green foliage, while excess nitrogen can delay or reduce blooming. Fertilisers for gardenias should focus on:

Low to moderate nitrogen: Prevents excessive foliage at the expense of flowers
High potassium: Encourages strong blooming and flower longevity
Calcium and magnesium: Essential for healthy foliage and chlorophyll production

Apply liquid fertiliser every 2–4 weeks during the active growing season (spring through early summer), and reduce feeding in autumn as the plant prepares for dormancy. Always water well after fertilising, and avoid fertilising during extreme heat or when the soil is dry. For gardenias grown in pots, flush the soil with clean water every 6–8 weeks to avoid fertiliser salt build-up. Monitor for signs of overfeeding (burnt leaf tips, rapid weak growth) and adjust frequency accordingly.

Fertilising Schedule for Gardenias:

Early Spring: Use a balanced fertiliser to stimulate new growth and bud formation
Mid-Spring to Summer: Switch to a flowering blend with higher potassium and micronutrients
Late Summer: Apply a final light feeding to strengthen plant structure before autumn

Pruning and Maintenance Tips:

Lightly prune after flowering to shape the shrub and encourage branching
Remove yellow or dead leaves regularly to keep air flowing and reduce fungal issues
Avoid hard pruning into old wood—gardenias may not regrow well from bare stems

Consistent watering, correct pH (5.0–6.5), partial sunlight, and regular feeding are the key to lush, fragrant gardenias that flower year after year.