Silphium perfoliatum

RHS Plant Profile
cup plant

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cup plant RHS

Other common names

cup rosin weed, Indian cup

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Herbaceous Perennial
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An upright perennial to 2.5m tall, with paired, oval leaves joined around the stem, and branched sprays of bright yellow daisies 7-9cm wide, opening in late summer

Position

Full sun, Partial shade

Soil Types

Loam

Max Height

1.5-2.5 metres

Max Spread

0.5-1 metres

Size

Time to Maturity
2–5 years
Max Spread
0.5-1 metres
Max Height
1.5-2.5 metres

Growing Conditions

Loam
Moisture
Moist but well–drained or Well–drained
pH
Acid or Alkaline or Neutral

Position

Full sun Partial shade
Aspect
West–facing or South–facing
Exposure
Exposed or Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

  • H1A: under glass all year (>15C)
  • H1B: can be grown outside in the summer (10 - 15)
  • H1C: can be grown outside in the summer (5 - 10)
  • H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
  • H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
  • H4: hardy through most of the UK (-10 to -5)
  • H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
  • H6: hardy in all of UK and northern Europe (-20 to -15)
  • H7: hardy in the severest European continental climates (< -20)
H7

Colour & Scent

Fragrance Foliage
Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Asteraceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Bushy
Genus
Silphium are robust herbaceous perennials with tall stems bearing simple leaves, aromatic when bruised, and loose clusters of yellow, daisy-like flowers in summer and early autumn
Name Status
Correct
Plant Range
E N America

How to Grow

Cultivation

An 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

Propagation

Propagate by seed or division

Suggested planting locations and garden types

  • Architectural
  • Cottage and informal garden
  • Flower borders and beds

Pruning

Cut back after flowering; stems may optionally be left until shortly before new growth begins the following season

Pests

Generally pest-free

Diseases

Generally disease-free