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.
⚠️ Keep soil evenly moist during germination. DO NOT LET IT DRY OUT—once seeds begin absorbing water (imbibition), drying can kill the seed embryo, and even brief dryness after sprouting can kill seedlings.
Seed Treatment
Soak seeds in room-temperature water for 6 hours before sowing. Sow immediately after soaking.
When to Sow
Indoors: Start 4–6 weeks (28–42 days) before your last frost date.
Outdoors: Direct sow after all danger of frost has passed and soil temperatures are consistently warm (at least 18°C / 65°F).
Germination Time: up to 21 days
How to Sow Indoors
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Fill trays or small pots with fine, well-draining seed-starting mix.
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Moisten soil evenly before sowing.
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Scatter seeds on the surface and gently press into the soil—do not cover. Seeds require light to germinate.
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Use grow lights to maintain 12–16 hours of light per day.
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Use a heat mat to maintain steady temperatures of 20–25°C (68–77°F)
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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.
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Once seedlings emerge, provide strong light and good airflow.
Transplant outdoors after frost when seedlings are 8–10 cm (3–4 in) tall and hardened off.
Post-Germination & Growing On
Plant type: Annual ornamental (also edible leaves and seeds)
Mature height: 90–150 cm (3–5 ft)
Final spacing: 30–45 cm (12–18 in) apart
Sun: Full sun
Soil: Well-draining, moderately fertile soil
Water: Moderate; drought tolerant once established
Pinch young plants when 20–25 cm (8–10 in) tall to encourage branching and fuller growth. Taller varieties may benefit from staking in windy areas.
Growing Tips
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Thrives in heat and poor soils—avoid over-fertilizing, which can reduce flowering.
• Excellent for dramatic borders, cottage gardens, and cut or dried flower arrangements.
• Self-seeds easily in warm climates.
• Seeds are edible and traditionally used as a grain in parts of South America.
More guides at: bloomoutlet.com/seed-guides