Helianthus 'Capenoch Star'

RHS Plant Profile
sunflower 'Capenoch Star'

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Herbaceous Perennial
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An herbaceous perennial making a clump to 1.5m tall, with rough, ovate leaves to 20cm long and flower-heads up to 20cm wide, with light yellow ray-florets notched at the tips and deeper yellow disks

Position

Full sun

Soil Types

Chalk, Clay, Loam

Max Height

1-1.5 metres

Max Spread

0.5-1 metres

Size

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

Growing Conditions

Chalk Clay Loam
Moisture
Moist but well–drained
pH
Alkaline or Neutral

Position

Full sun
Aspect
West–facing or South–facing or East–facing
Exposure
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)
H5

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Asteraceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Bushy
Genus
Helianthus can be tall, erect annuals, tuberous or rhizomatous perennials, with coarse simple leaves and large daisy-like flower-heads
Name Status
Accepted

How to Grow

Cultivation

Grow in a moderately fertile, humus-rich, moist but well-drained, neutral to alkaline soil in full sun. Needs a long hot summer to flower well. May need support

Propagation

Propagate by seed or division. Divide established clumps every 2-4 years to both increase plants and retain vigour. See sowing seeds indoors for further advice

Suggested planting locations and garden types

  • City and courtyard gardens
  • Coastal
  • Cottage and informal garden
  • Flower borders and beds

Pruning

Cut back after flowering

Pests

May be susceptible to slugs and snails

Diseases

May be susceptible to powdery mildews and sclerotinia diseases