• 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

Oenothera macrocarpa

Ozark sundrops

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
Ozark sundrops

© RHS 2002

  • Other common names Ozark sundrops

  • Synonyms Oenothera missouriensis

  • Family Onagraceae

  • Genus Oenothera can be annuals, biennials or perennials, upright or spreading in habit, with simple or lobed leaves and bowl-shaped, white, yellow or pink flowers over a long period in summer

  • Details O. macrocarpa is an herbaceous perennial to 15cm in height, with trailing leafy stems to 30cm in length. Leaves narrowly oblong, with conspicuous silvery midribs; flowers solitary, 10-12cm in width, bright yellow, appearing from late spring to early autumn

  • Plant range Central southern USA

Characteristics

  • Foliage Deciduous

  • Habit Trailing

  • 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 East-facing

  • Exposure Exposed

Soil

  • Chalk

    Chalk

  • Loam

    Loam

  • Sand

    Sand

  • MoistureWell-drained

  • SoilChalk, Loam, Sand

  • pHAlkaline, Neutral, Acid

Size

  • Ultimate height 0.1-0.5 metres

  • Ultimate spread 0.1-0.5 metres

  • Time to ultimate height 2-5 years

How to grow

Cultivation Grow in poor to moderately fertile, well-drained soil in full sun; ideal for stony soil. Protect from excessive winter wet

Propagation Propagate by seed sown in pots in a cold frame in early spring

Suggested planting locations and garden types Banks and Slopes Flower borders and beds Garden Edging City & Courtyard Gardens Cottage & Informal Garden Gravel Garden Mediterranean Climate Plants Patio & Container Plants Rock Garden

How to care

Pruning No pruning required

Pests Damage by slugs may be a problem

Diseases Prone to leaf spots, mildews and root rot

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