Oenothera speciosa (Showy Evening Primrose)

Seed Treatment (Pre-Sowing)

  • COLD STRATIFICATION:

    1. Place seeds in a damp paper towel or mix with moist vermiculite.
    2. Seal in a plastic bag and refrigerate for 2–4 weeks at 40°F (4°C). 
    3. Check regularly: If seedlings sprout in the fridge, remove them gently and plant immediately.
    4. After stratification, sow as normal.
  • Optional soaking: For faster germination, soak seeds in warm water for 12–24 hours before sowing.

Sowing Instructions

  • When to sow outdoors:
     Late fall (for natural stratification) or early spring.
  • When to sow indoors:
     6–8 weeks before last expected frost date.
  • Seed depth:
     Do not cover deeply. Sow on the surface or lightly press into soil — seeds need light to germinate.
  • Spacing:
     Space plants 12–18 inches (30–45 cm) apart.
  • Germination time:
     Usually 10 to 45 days AFTER stratification
  • Germination temperature:
     Ideal is 65–75°F (18–24°C). Use grow lights to maintain 12–16 hours of light per day.

Growing Conditions

  • Sunlight: Full sun preferred; tolerates partial shade.
  • Soil: Well-drained sandy or loamy soil. Tolerates poor soils.
  • Water:  Keep moist during germination. Once established, drought-tolerant.
  • USDA Zones: 4–9. May die back in winter but returns in spring.

? Additional Tips

  • Deadhead to prolong blooming and limit aggressive self-seeding.
  • Great for wildflower gardens, borders, and naturalized spaces.
  • Attracts bees, butterflies, and other pollinators.

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