Perennial • $6, 5-inch pot
Height | 5 to 10 ft |
Spacing | 2 to 3 ft |
Sun Exposure | Full to Part Sun |
Soil Moisture | Medium Wet |
Bloom Color | Yellow |
Bloom Time | Aug – Sept |
Companion Plantings | Switchgrass, Pasture Thistle, Wild Bergamot |
Special Attributes |
Silphium perfoliatum
This tall, iconic prairie forb can grow to 10 feet on sturdy, square stems that support bright, 2-inch yellow ray flowers in mid-summer. This plant will need several feet of space in the garden, but grows primarily from a central taproot and is not too aggressively rhizomatous like many other prairie plants. This plant does have a tendency to form colonies, however, so it is not without maintenance. The very large, roughly serrated leaves are perfoliate, meaning they fully wrap and connect around the main stem, which for this plant results in a little “cup” that can hold water, hence the common name. Cup Plant prefers wetter sites but is nonetheless easy to grow and will adapt to average garden conditions.
Large bees, butterflies and skippers are the main pollinators of Cup Plant, although smaller bees and even flies may also visit the flowers. The water-holding capacity of the leaves draw birds and even small animals seeking a drink. Birds will also feed on the seeds, which are easy to grow if sowed in the fall or cold-moist stratified for at least 60 days before planting. The large leaves and stature of the plant also make it a great cover for birds and other wildlife.
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