About
Silphium perfoliatum, the cup plant, is an upright, robust perennial to 2.5 m producing paired, oval, coarsely toothed leaves joined around the stem to form a cup that collects rainwater, and branched sprays of bright-yellow daisies 7�9 cm wide in late summer. A bold and ecologically rewarding prairie perennial for a large, sunny border.
About the genus
Silphium are robust herbaceous perennials with tall stems bearing simple, aromatic leaves and loose clusters of large, yellow, daisy-like flowers in summer and early autumn. Bold and rewarding plants for a large, sunny, well-drained border or prairie planting.
Growing conditions
SunlightFull sun, Partial shade
Soil typeLoam
Soil pHAcid, Alkaline, Neutral
Soil moistureMoist but well-drained, Well-drained
AspectWest-facing, South-facing
ExposureExposed, Sheltered
UK hardinessH7
Plant details
Plant typeHerbaceous Perennial
HabitBushy
FoliageDeciduous
Height1.5-2.5 metres
Spread0.5-1 metres
Time to full height2-5 years
Suggested usesArchitectural, Cottage and informal garden
Native toE N America
FragranceFoliage
Care notes
CultivationAn impressive plant suitable for the back of a border. It performs best when grown in full sun; in partial shady, or windy, sites it may require staking
PruningCut back after flowering; stems may optionally be left until shortly before new growth begins the following season
PropagationPropagate by seed or division
Pest resistanceGenerally pest-free
Disease resistanceGenerally disease-free