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:
Step 1: Cold stratification - Place seeds in a moist medium (damp paper towel or seed mix) inside a sealed bag. Refrigerate at 1–4 °C (34–39 °F) for 60 days.
Step 2: Soaking (after stratification) - After completing cold stratification, soak seeds in room-temperature water for 24 hours before sowing.
Check regularly: If seedlings sprout in the fridge, remove them gently and plant immediately.
When to Sow
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Indoors: Late winter to early spring after cold stratification.
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Outdoors (natural stratification): Fall sowing. Scatter seeds on prepared soil, lightly cover, and allow winter cold to stratify naturally.
Germination Conditions
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Optimum temperature: Use a heat mat to maintain steady temperatures of 20–25 °C (68–77 °F)
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Germination time: up to 90 days after stratification
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Light for germination: Not required (germinates in darkness)
How to Sow Indoors
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Use a sterile, well-draining seed-starting mix.
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Sow seeds 6–10 mm (¼–⅜ in) deep and gently firm the soil.
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Water thoroughly and keep evenly moist.
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 after emergence: Use grow lights to maintain 12–16 hours of light per day.
Post-Germination Care
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Plant type: Herbaceous perennial
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Mature height: 60–90 cm (24–36 in)
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Final spacing: 30–45 cm (12–18 in)
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Transplant carefully once seedlings have several true leaves. Harden off before moving outdoors.
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Prefers full sun to light shade and well-drained soil.
Growing Tips
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Avoid waterlogged soil—good drainage is essential.
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Flowering typically begins in the second year from seed.
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Seed pods split open in fall, revealing decorative blackberry-like seeds.
More guides at: bloomoutlet.com/seed-guides