Silphium perfoliatum (Cup Plant)

Very architectural, Silphium perfoliatum (Cup Plant) is an upright perennial with tall, sturdy, squarish stems clad with paired, oval leaves joined around the stem to form a small cup that holds water and attracts birds. Blooming for 4-6 weeks in midsummer to early fall, branched sprays of deep yellow daisies, 3 in. across (7 cm), adorned with 20-30 yellow rays surrounding a darker yellow central disk, can be enjoyed. Cup Plant attracts many visitors, including honey bees, bumblebees, and big showy butterflies. The flowers are followed by seeds that are favored by birds. Cup Plant blackens after a freeze and remains erect even in death, providing an architectural presence into winter. This species is also commonly called Cup Rosin Weed because its stems exude a gummy, bitter resin when broken or cut. Silphium perfoliatum is an impressive plant suitable for the back of a border and a great choice for prairies or other natural plantings.

• Recipient of the prestigious Award of Garden Merit of the Royal Horticultural Society.
• Grows up to 4-8 ft. tall (120-240 cm) and 1-3 ft. wide (30-90 cm). Self-sows prolifically. The root system consists of a central taproot, and abundant shallow rhizomes that help to spread the plant, often forming large colonies.
• Performs best in full sun in average, medium to wet, well-drained soils. Prefers moist, rich soils, but tolerates some drought once established.
• No serious pest or disease issues.
• Great for prairies or meadows, cottage gardens, wildflower gardens and beds and borders.
• Propagate by seed. Sow unstratified seeds in fall or stratified seeds in spring.
• Silphium perfoliatum has become invasive in New England where it has been introduced.
• Native to eastern North America.