Cup plant (Silphium perfoliatum) SILL-fee-um per-fo-lee-AY-tum Genus:  Silphium A coarse but bold perennial giant for the back of the border with yellow, daisy-like flowers in summer. Cups form where the toothed leaves meet the thick stems; birds are said to drink from the water held in the cups. Tough prairie natives that will self-sow, these plants need lots of sun and lots of room—a single plant can reach 7 or 8 feet tall and 6 feet across. Care:  Provide moist, moderately rich, well-drained, neutral to alkaline soil for best results, but plants are fairly adaptable. Propagation:  Sow ripe seeds. Divide in spring. Problems:  Downy mildew, rust.

Overview

Height 6 ft. to 10 ft. Spread 3 ft. to 6 ft. Growth Habit Clumps Growth Pace Fast Grower, Invasive/Aggressive Grower Light Full Sun to Part Shade Moisture Medium to Wet Maintenance Moderate Characteristics Attracts Song Birds, Attracts Butterflies, Native, Self Seeds, Showy Flowers Bloom Time Early Fall, Late Summer, Summer Flower Color Yellow Uses Beds and Borders, Naturalizing, Screening Style Cottage Garden, Meadow Garden Seasonal Interest Summer Interest Type Perennials