Best Fertiliser for Crossandra Plant: How to Grow, Feed & Care for Firecracker Flowers in Australia

Crossandra infundibuliformis—commonly known as Firecracker Flower—is a tropical evergreen that’s celebrated for its vivid orange, salmon, and coral blooms. This low-maintenance plant is perfect for warm Australian climates, thriving in courtyards, pots, and tropical-style garden beds. To get the most out of its long flowering season, proper fertilisation is essential. This guide covers everything you need to grow vibrant, blooming Crossandra plants from soil prep to fertiliser timing.

Crossandra Plant Basics – Structure, Flowering & Landscape Use

Crossandra is a flowering tropical subshrub native to southern India and Sri Lanka, adapted to warm, humid conditions. With its lush green foliage and eye-catching funnel-shaped flowers, it’s a standout choice for borders, patio pots, or mixed tropical plantings. It performs well in the subtropical and tropical regions of Queensland, Northern NSW, and WA, and can be grown as a summer annual or overwintered in frost-free zones. Key characteristics:

Botanical name: Crossandra infundibuliformis
Common names: Firecracker Flower, Orange Marmalade Plant, Crossandra
Height & spread: Grows 30–90 cm tall; forms compact mounds
Foliage: Glossy, dark green leaves with a soft texture; evergreen in warm zones
Flowers: Clusters of tubular orange, pink, or coral flowers appearing spring through autumn

Crossandra is a popular choice for:

Mass planting in tropical or subtropical gardens
Container gardening on balconies or patios
Understory plantings in light shade

The plant is known for flowering continuously in warm weather and can bloom for many months if properly cared for. Its tolerance for humidity and part shade makes it a favourite in eastern coastal areas of Australia. While Crossandra is relatively pest-resistant, it thrives best when consistently watered, protected from frost, and fed with a nutrient-rich fertiliser.

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How to Grow & Care for Crossandra Plants in Australia

To achieve lush foliage and prolific flowering, Crossandra requires warmth, filtered light, and moisture-retentive but free-draining soil. Although it’s often treated as an annual in cooler climates, it can thrive for years in warmer areas if given adequate protection from wind and cold. Essential growing conditions:

Light: Crossandra prefers bright, indirect light or part sun. Too much shade reduces blooms, while full, direct sun in summer may scorch leaves.
Soil: Needs well-draining soil rich in organic matter. A loamy or sandy mix with some moisture retention is ideal. Avoid clay or waterlogged beds.
Temperature: Performs best in 20–30°C; avoid exposure below 10°C. In colder climates, overwinter indoors or under cover.
Watering: Water regularly, keeping the soil evenly moist but not soggy. Allow the top layer to slightly dry between waterings. Never let Crossandra completely dry out.
Humidity: Prefers moderate to high humidity. Mist occasionally or group with other plants to raise ambient moisture in dry conditions.

Care & maintenance tips:

Deadheading: Regularly remove spent flowers to encourage more blooms and a tidy shape.
Pruning: Lightly trim back stems after flowering flushes to promote bushy regrowth.
Repotting: For potted plants, refresh the soil and upgrade containers every 12–18 months.
Pests: Generally pest-free but occasionally affected by aphids, spider mites, or mealybugs in dry indoor air.

Crossandra’s adaptability makes it ideal for beginner gardeners. It can be grown as a companion plant with impatiens, coleus, or begonias in mixed tropical arrangements. However, its flowering power is directly tied to nutrient availability, making regular feeding a must for dense growth and colour vibrancy.

Understanding Crossandra Fertiliser Needs – What, When & How to Feed

Crossandra is a moderate-to-heavy feeder, particularly during its flowering cycles in spring through early autumn. It requires a fertiliser strategy that supports both foliage health and bloom production, especially in containers where nutrients deplete quickly. Key nutrient needs:

Nitrogen (N): Promotes healthy leaf and stem development during the early season
Phosphorus (P): Supports strong root formation and sustained flowering
Potassium (K): Enhances flower size, colour intensity, and plant resilience

Recommended fertilising schedule:

Spring (start of active growth): Begin with a balanced fertiliser like NPK 20-20-20 to support robust foliage and new growth. Apply every 2 weeks.
Early Summer to Autumn: Shift to a bloom-boosting fertiliser high in potassium, such as NPK 4-18-38, to fuel extended flowering. Apply fortnightly.
Winter (dormant or low growth period): Reduce or stop fertilising entirely to allow the plant to rest. Resume in early spring.

Application tips:

Use liquid fertiliser diluted according to instructions for even nutrient distribution.
Feed after watering to avoid root burn.
Flush pots occasionally with water to prevent salt build-up, especially when feeding frequently.

Avoid common mistakes like overfeeding, which may cause leggy growth and reduced flowering. Pale or yellowing leaves often indicate nitrogen or iron deficiency, which can be corrected with a complete micronutrient-enriched feed. For gardeners seeking vibrant, repeat-flowering Crossandra, we recommend starting the season with CompleteGrow’s All Purpose Liquid NPK 20-20-20 during active leafy growth, followed by CompleteGrow’s NPK 4-18-38 + CaMg formula once flowering begins. These professional-grade formulations provide balanced macro and micronutrients to support lush foliage, flower density, and long-term plant health.