• AGM plants

    AGM plants have been through a rigorous trial and assessment programme. They are:

    • Excellent for ordinary use in appropriate conditions
    • Available to buy
    • Of good constitution
    • Essentially stable in form & colour
    • Reasonably resistant to pests & diseases

Helianthus × laetiflorus

showy sunflower

  • Other common names showy sunflower
    perennial sunflower

  • Synonyms Helianthus rigidus misapplied
    Helianthus scaberrimus

  • Family Asteraceae

  • Genus Helianthus can be tall, erect annuals, tuberous or rhizomatous perennials, with coarse simple leaves and large daisy-like flower-heads

  • Details

    Helianthus x laetiflorus is a rhizomatous, clump-forming perennial to 2m tall with dark green, narrowly-ovate and toothed leaves. Bright yellow flowerheads with dark centres,10-12cm in diameter, are borne from late summer into autumn

Characteristics

  • Foliage Deciduous

  • Habit Bushy

  • 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

Sunlight

  • Full Sun

  • Aspect South-facing or West-facing or East-facing

  • Exposure Exposed or Sheltered

Soil

  • Sand

    Sand

  • Chalk

    Chalk

  • Loam

    Loam

  • MoistureMoist but well-drained

  • SoilSand, Chalk, Loam

  • pHAlkaline, Neutral

Size

  • Ultimate height 1.5-2.5 metres

  • Ultimate spread 1-1.5 metres

  • Time to ultimate height 2-5 years

How to grow

Cultivation Requires a moderately fertile, moist but well-drained, alkaline to neutral soil in full sun

Propagation Propagate by seed in the spring. Divide established clumps every 2-4 years to both increase plants and retain vigour

Suggested planting locations and garden types Flower borders and beds Cut Flowers City & Courtyard Gardens Coastal Cottage & Informal Garden

How to care

Pruning Cut back old stems after flowering as they die down for the winter

Pests Susceptible to slugs

Diseases Powdery mildews and sclerotinia diseases may be a problem

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