Campanula glomerata (Clustered Bellflower)

Seed Treatment

  • Mix seeds with moist sand, vermiculite, or paper towel.
  • Place the mix in a sealed plastic bag.
  • Refrigerate at 35–40°F (1–4°C) for 4–6 weeks.
  • After stratification, sow seeds indoors or directly outdoors in early spring.
    You can also direct sow in late fall for natural winter stratification.

When to Sow

  • Indoors: 6–8 weeks before your last frost date
  • Outdoors: Early spring or late fall

Soil Requirements

  • Well-draining, moderately fertile soil
  • Works well in sandy, loamy, or light clay soils
  • Ideal pH: 6.0–7.5

Light Requirements

  • Full sun to partial shade
  • Provide light afternoon shade in hot climates

Sowing Depth

  • Surface sow; do not cover or only lightly dust with fine soil or vermiculite
  • Press seeds gently into the soil to ensure contact

Watering

  • Keep soil evenly moist during germination
  • Mist gently to avoid washing away surface seeds

Germination Time

  • 14–28 days at 65–70°F (18–21°C)

Spacing

  • Thin or transplant seedlings to 12–18 inches (30–45 cm) apart

Growing Tips
Campanula glomerata produces vibrant clusters of bell-shaped violet-blue flowers in early to midsummer. It’s great for borders, cottage gardens, and pollinator patches. Deadhead to extend flowering and reduce self-seeding. Plants are deer-resistant and attract pollinators. Cut back after flowering to promote a tidy appearance and fresh foliage.