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 warm water for 12–24 hours before sowing.
When to Sow
Indoors: Start seeds 4–6 weeks (28–42 days) before your last expected frost date.
Germination Conditions
Optimum temperature: Use a heat mat to maintain steady temperatures of 70–85°F (21–29°C)
Germination time: 7 to 21 days
Light requirements: Seeds need light to germinate. Surface sow.
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 seed trays or shallow pots with a fine, well-draining seed-starting mix.
Gently press soaked seeds onto the surface—do not cover with soil. Mist lightly to keep surface moist.
Place under grow lights in a warm area.
Post-Germination Care
Once seedlings develop true leaves, transplant to individual pots or directly into the garden after hardening off.
Final spacing: 10–18 inches (25–45 cm) apart.
Plant type: Annual ornamental (also edible—young leaves are nutritious).
Mature height: 2–4 feet (60–120 cm), depending on variety.
Prefers full sun and fertile, well-drained soil. Water moderately.
Remove spent flower heads to encourage continued growth and color.