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 (Before Planting)
Step 1: Soak seeds in warm water for 2–4 hours if they are more than one year old.
Step 2: Cold stratify in a moist paper towel or vermiculite inside a sealed bag for 14–21 days in the refrigerator (1–4°C / 34–39°F).
When to Sow Indoors
Start seeds indoors 6–8 weeks (42–56 days) before the last expected frost.
When to Sow Outdoors
For natural stratification, sow seeds outdoors in late fall. Press seeds gently into moist soil and allow winter chill to break dormancy naturally.
Optimum Germination Temperature: 10–15°C (50–59°F)
Germination Time: 14–30 days after stratification
Light Requirements for Germination
Requires light to germinate. Do not cover seeds.
Use grow lights to maintain 12–16 hours of light per day.
How to Sow Indoors
Sow on the surface of moist seed-starting mix in trays or pots. Press gently to ensure contact but do not bury.
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.
Post-Germination Care
Thin or transplant seedlings when they develop their second set of true leaves. Final plant spacing: 20–30 cm (8–12 in).
Type: Hardy annual
Mature height: 60–100 cm (24–40 in)
Prefers full sun and well-drained soil. Avoid disturbing roots when transplanting—use biodegradable pots if starting indoors.
Growing Tips
Water regularly during dry spells but avoid soggy soil. Taller plants may need staking. Deadhead to prolong blooming or allow some flowers to go to seed for self-sowing.