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 (Before Planting)
Step 1: Soak seeds in warm water for 2–4 hours before sowing.
When to Sow Outdoors
Direct sow outdoors in early spring while nights are still cold, or in late fall for natural stratification. Scatter seeds on the soil surface and press in lightly — do not cover. Cold outdoor temperatures naturally break dormancy.
How to Sow Indoors
Sow in seed trays filled with moist, well-draining seed-starting mix. Gently press seeds onto the surface — do not cover, as they need light to germinate.
Use biodegradable pots or soil blocks to avoid disturbing roots during transplanting.
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.
Light Requirements for Germination
Requires light to germinate. Use grow lights to maintain 12–16 hours of light per day.
Optimum Germination Temperature: 15–18°C (59–65°F)
Germination Time: 10–28 days
Post Germination Care
Once seedlings develop their first true leaves, thin or transplant to final spacing.
Final Spacing: 20–30 cm (8–12 in) apart
Type: Hardy annual
Mature Height: 60–120 cm (2–4 ft)
Growing Tips:
- Prefers full sun and well-draining soil.
- Avoid disturbing roots when transplanting — use biodegradable pots if starting indoors.
- Water moderately; overwatering can cause damping off.
- Deadhead to extend blooming or allow seed heads to dry for reseeding.