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Photos are representative and may not match your specific variety.
Cup Plant
Native wildflower
Native wildflowerSilphium perfoliatum
- Partial sun
- Zones 3–9
- 60 days to maturity
- Flowers
- 36" spacing
- High water
- pH 6–8
Overview
Cup Plant (Silphium perfoliatum) is a perennial native wildflower. Hardy in USDA zones 3 to 9. Prefers full sun.
Planting
Direct sow in fall (September–November) for natural cold stratification, or start indoors 6–8 weeks before last frost after 30-day cold stratification in moist medium
Growing
Sun: partial. Water: high. Soil pH: 6–8. Space plants 36" apart. Germination: 10–21 days.
Pests & diseases
Common pests: Japanese beetles, grasshoppers (rarely problematic). Common diseases: Powdery mildew in humid conditions (with poor air circulation); generally disease-resistant.