How to grow calibrachoa
Overview
Calibrachoa is a herbaceous perennial grown for its abundant, petunia-like flowers and trailing habit. It thrives in full sun and requires consistent moisture and regular feeding to sustain heavy blooming through warm months.
Varieties
- Calibrachoa 'Million Bells' — Trailing series with small, bell-shaped flowers in pink, purple, yellow, and white; very popular in Australian hanging baskets.
- Calibrachoa 'Superbells' — Larger-flowered series with improved heat tolerance; ideal for subtropical and tropical gardens.
- Calibrachoa 'Cabaret' — Compact, mounding habit with bicolour blooms; suits ground cover and mixed containers in temperate zones.
Soil Preparation
Prefers slightly acidic soil (pH 5.5–6.5) with excellent drainage. Amend heavy clay with coarse sand or perlite; use a soilless mix for baskets. Add compost for organic matter but avoid water-retaining gels that cause sogginess.
Growing Guide
Plant in full sun with well-drained soil or premium potting mix. Space 20–30 cm apart for ground cover or 3–5 per 30 cm basket. Use slow-release fertiliser at planting and liquid feed fortnightly. Pinch tips at 10 cm to encourage branching; avoid overwatering to prevent root rot.
Sowing
Sow seeds on surface, barely cover, and keep at 20–25°C; germination takes 10–14 days. Transplant when 4 true leaves appear. Direct sowing is unreliable—use punnets or plugs for best results.
Care
Feed every 2 weeks with a balanced liquid fertiliser (e.g., 10-10-10) during active growth. Deadhead spent flowers to maintain vigour; cut back by one-third in late summer to rejuvenate. Avoid overhead watering to reduce disease risk.
Companion Planting
Pair with petunias, lobelia, and verbena for colour contrast. Avoid planting near heavy feeders like tomatoes that may compete for nutrients; also keep away from invasive groundcovers that could smother calibrachoa.
Common Pests & Risks
Aphids and spider mites are common, especially in dry weather. Control with neem oil or insecticidal soap; encourage beneficial insects like ladybirds. Whitefly may also appear—use yellow sticky traps and avoid over-fertilising.
Troubleshooting
Yellow leaves: overwatering or nitrogen deficiency—let soil dry and feed with balanced fertiliser. Brown leaf edges: salt burn from over-fertilising—leach soil with water. Leggy growth: insufficient light—move to full sun or pinch back. Few flowers: low phosphorus or heat stress—use a bloom booster and provide afternoon shade in extreme heat. Root rot: poor drainage—repot in fresh mix with perlite.