Calibrachoa, often called "million bells," is a popular flowering plant known for its vibrant, trumpet-shaped blooms. While it is commonly propagated through cuttings, growing Calibrachoa from seeds is possible but comes with challenges. From a botanical perspective, Calibrachoa seeds are tiny and require specific conditions to germinate successfully. Unlike hybrid varieties, which may not produce true-to-type seeds, open-pollinated or heirloom Calibrachoa varieties are more likely to yield viable seeds.
To grow Calibrachoa from seeds, start by collecting seeds from mature, dried seed pods. The seeds are minuscule, so handle them carefully. Clean the seeds by removing any chaff or debris to prevent fungal issues. Some growers recommend soaking the seeds in lukewarm water for 24 hours to soften the seed coat, though this step is optional. Proper storage in a cool, dry place is essential to maintain seed viability until planting.
Calibrachoa seeds require consistent warmth (70–75°F or 21–24°C) and light to germinate. Use a sterile, well-draining seed-starting mix and lightly press the seeds onto the surface without covering them, as they need light to sprout. Maintain high humidity by covering the tray with a plastic dome or plastic wrap. A grow light or bright, indirect sunlight is crucial for successful germination, which typically takes 10–14 days.
Once seedlings emerge, remove the cover to improve air circulation and prevent damping-off disease. Keep the soil moist but not waterlogged. When seedlings develop 2–3 true leaves, transplant them into individual pots. Use a nutrient-rich, well-draining potting mix and provide bright, indirect light. Gradually acclimate the seedlings to outdoor conditions if planting them in gardens or containers.
Growing Calibrachoa from seeds can be tricky due to low germination rates and slow initial growth. To improve success, use fresh seeds and maintain optimal temperature and light conditions. Fungal infections are common, so ensure proper airflow and avoid overwatering. If seeds fail, consider purchasing high-quality seeds from reputable suppliers or propagating through cuttings for more reliable results.
Calibrachoa thrives in full sun to partial shade and prefers slightly acidic, well-draining soil. Regular watering and balanced fertilization every 2–3 weeks support healthy growth and prolific blooming. Pinch back young plants to encourage bushiness. In colder climates, Calibrachoa is often grown as an annual, but it can be overwintered indoors in pots.
