• 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

Stratiotes aloides

water soldier

  • Other common names water soldier
    crab's claw

    freshwater soldier
    knight's pondwort
    knight's wort
    knight's woundwort
    soldier's yarrow
    wading pondweed
    water aloe
    water houseleek
    water sengreen
    water soldiers

    see more
  • Family Hydrocharitaceae

  • Genus Stratiotes are vigorous, dioecious, submerged aquatic perennials forming stalkless rosettes of toothed, sword-shaped leaves, with white or pinkish 3-petalled flowers, the females solitary, the males in small clusters

  • Details S. aloides is a stoloniferous perennial forming rosettes of narrow, sharp-pointed leaves to 45cm in length, with white flowers, 3cm across, in summer

  • Plant range Europe, N Asia


  • Foliage Deciduous

  • Habit Tufted

  • 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)




  • Full Sun

  • Aspect South-facing or West-facing

  • Exposure Exposed or Sheltered


  • Clay


  • Loam


  • Sand


  • MoisturePoorly-drained

  • SoilClay, Loam, Sand

  • pHAlkaline


  • Ultimate height Up to 10 cm

  • Ultimate spread 0.5-1 metres

  • Time to ultimate height 5-10 years

How to grow

Cultivation Grow in slightly akaline water, deeper than 30cm in full sun. This plant is listed on Schedule 9 of The Wildlife (Northern Ireland) Order (1985), as amended, as an invasive non-native species. While this does not prevent it from being sold or being grown in gardens in Northern Ireland, 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 in Northern Ireland 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 removal of plantlets

Suggested planting locations and garden types Low Maintenance Wildlife Gardens

How to care

Pruning Remove runners to restrict spread

Pests Generally pest free

Diseases Generally disease free

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