Silphium perfoliatum

Scientific Name: Silphium perfoliatum

Common Name: Cup Plant

Exposure: Full sun to partial shade

Blooming Time: July to September

Bloom Duration: 2 to 3 months

Fragrance: No noticeable fragrance

Plant Growing Habit: Upright, clump-forming, tall

Characteristics: A striking North American native perennial featuring tall, sturdy stems with large, opposite leaves that join around the stem to form water-holding “cups.” Produces bright yellow, sunflower-like blooms that attract bees, butterflies, and other pollinators. The seeds provide valuable food for songbirds, and the dense growth offers habitat for wildlife. Excellent for native gardens, pollinator gardens, rain gardens, meadows, and naturalized landscapes.

Spacing: 60 to 90 cm apart

Height: 150 to 250 cm

Width: 60 to 120 cm

Maintenance Requirements: Low to moderate maintenance. Prefers full sun and moist, fertile, well-drained soil but adapts to average garden conditions. Water regularly during establishment; once established, it is drought-tolerant. Tall stems may benefit from support in windy locations. Remove spent flowers to reduce self-seeding if desired, or leave seed heads standing for winter interest and wildlife value. Cut back old stems in late fall or early spring before new growth emerges. Fertilization is rarely required. Hardy and well-suited to Canadian gardens in Zones 3–8.

Images Courtesy of Ball Horticultural Company of Ball Seed or www.ballseed.com