• 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

Sagittaria latifolia

wapato

wapato

© RHS 2002

  • Other common names wapato
    duck potato

    American arrowhead
    various-leaved arrowhead

    see more
  • Family Alismataceae

  • Genus Sagittaria can be marginal or submerged aquatic, tuberous perennials or annuals, with linear, lance-shaped or arrow-shaped leaves and panicles of 3-petalled white flowers in summer

  • Details S. latifolia is a marginal aquatic perennial with usually arrow-shaped leaves, to 30cm in length, and racemes of whorled white flowers, 4cm across, in summer

Characteristics

  • Foliage Deciduous

  • Habit Clump-forming

  • 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)

    H6

Colour

Sunlight

  • Full Sun

  • Aspect South-facing or West-facing

  • Exposure Exposed or Sheltered

Soil

  • Sand

    Sand

  • Clay

    Clay

  • Loam

    Loam

  • MoisturePoorly-drained

  • SoilSand, Clay, Loam

  • pHNeutral, Acid, Alkaline

Size

  • Ultimate height 0.5-1 metres

  • Ultimate spread 0.1-0.5 metres

  • Time to ultimate height 5-10 years

How to grow

Cultivation This plant is listed on Schedule 9 of the UK Wildlife & Countryside Act as an invasive non-native species. While this does not prevent it from being sold in the UK, or from being grown in gardens, the RHS encourages those that do grow it to take great care with managing it and with disposing of unwanted material. The RHS also encourages gardeners to find alternative plants to grow to those listed on Schedule 9. For suggested alternative plants see the Plantlife/RHS guide: Gardening without harmful invasive plants

Propagation Propagate by seed or by runners in summer. Alternatively, plant overwintered tubers in spring

Suggested planting locations and garden types Low Maintenance Wildlife Gardens

How to care

Pruning Cut back in late summer and remove dead flowerheads to prevent self-seeding

Pests Leaves may be damaged by water lily aphids

Diseases Generally disease free

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