For optimal germination rates, initiate seed propagation indoors under controlled conditions—unless the species exhibits a high sensitivity to root disturbance. This approach allows precise regulation of temperature, humidity, and light, improving germination consistency and seedling viability. Do not skip any recommended seed treatments, as they are essential for uniform and successful germination.
Seed Treatment
Soak seeds in lukewarm water for 12–24 hours before sowing.
When to Sow
Indoors: Start seeds 4–6 weeks (28–42 days) before the last expected frost.
Outdoors: Direct sowing is possible after the last frost, but indoor sowing is recommended for best results.
Germination Conditions
Temperature: 65–70°F (18–21°C)
Germination Time: 7–21 days
Light: Seeds require light to germinate. Use grow lights to maintain 12–16 hours of light per day.
Humidity: Use a humidity dome or clear cover to maintain consistent moisture during germination. Open the dome BRIEFLY once per day to allow fresh air in and reduce mold risk. Remove the dome entirely once seedlings emerge.
How to Sow Indoors
- Use a sterile, well-draining seed-starting mix.
- Surface sow the seeds—do not cover with soil. Press lightly onto the surface to ensure good contact.
- Keep the surface evenly moist using a spray bottle or fine mist.
Post-Germination Care & Growing Tips
- Remove humidity dome once seedlings emerge.
- Provide bright light (sunny windowsill or grow light) to prevent legginess.
- Harden off seedlings before transplanting outdoors.
- Final spacing: 10–12 inches (25–30 cm) apart.
- Mature height: 18–24 inches (45–60 cm).
- Plant type: Fast-growing annual.
- Prefers full sun and well-drained soil.
- Deadhead spent blooms to prolong flowering.