Silphium perfoliatum | Cup Plant
The Cup Plant, also known as Carpenter’s Weed, Indian Cup, Rosin Weed, and Ragged Cup, is a towering, showy sunflower-like perennial with a native range from eastern-central Canada to the southeastern United States. It is most commonly found in low woods, prairies, meadows, and bordering streams or ponds. It’s an extremely hardy, low-maintenance plant that can survive in a variety of temperatures and locations. It establishes well in average garden soil or in heavier, wetter soils. It’s a large plant that requires ample growing space. If you like large, robust specimens, this plant is for you! The root system consists of a long central tap root and many shallow rhizomes. The rhizomes help to spread the plant, forming substantial colonies over time. Although the cup plant can appear weedy to some folks, it’s well-suited for prairies, wildflower gardens, naturalized areas, or for bordering a stream or a pond.
Silphium perfoliatum is known for it’s bright yellow daisy-like blooms, coarse leaves, and long stems. The name “cup plant” (perfoliatum) comes from the shape of the leaves that clasp the main stem, making it look like the stem has pierced through them. The joined leaves form a small basin that enables them to hold water. It’s not uncommon to see birds or insects sipping water from the small pools on a hot day during the growing season, which is July through September. Pollinators are attracted to the large, bright yellow blooms, and birds enjoy the nutritious seeds too.
Best to start from seed by fall/winter planting outdoors. If sowing indoors, or outdoors in spring, a period of 60 days of moist, cold stratification is recommended.
Sun exposure: Full sun
Mature height: 8-10 ft
Mature width: 4-5 ft
Hardiness zones: 3-9
*Please note: We cannot ship Silphium perfoliatum Cup Plant seeds to Connecticut, New Hampshire, and New York at this time. Checkout is disabled for this product in these states.