• 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

Butomus umbellatus

flowering rush

flowering rush

© � RHS 2002

  • Other common names flowering rush
    grassy rush

    lily grass
    water gladiolus

    see more
  • Genus Butomus are submerged rhizomatous perennials with narrowly strap-shaped leaves and 6-petalled pink flowers held in umbels well above water level

  • Family Butomaceae / Butomaceae

  • Details B. umbellatus is an herbaceous perennial to 1.2m, with upright, twisted grassy leaves and stiff stems bearing umbels of fragrant rosy-pink flowers 2cm in width in late summer

  • Plant range Eurasia


  • Foliage Deciduous

  • Habit Submerged



  • Full Sun

  • Aspect South-facing or West-facing

  • Exposure Sheltered or Exposed


  • Chalk


  • Chalk


  • Chalk


  • MoisturePoorly-drained

  • SoilSand, Clay, Loam

  • pHNeutral, Acid, Alkaline


  • Ultimate height

    1-1.5 metres

  • Ultimate spread

    0.1-0.5 metres

  • Time to ultimate height

    5-10 years

How to grow

Cultivation Grow in fertile mud at pond margins or in water up to 25cm deep, in full sun

Propagation Propagate by seed sown as soon as ripe or by rhizome division in spring

Suggested planting locations and garden types Cottage & Informal Garden Wildlife Gardens

How to care

Pruning Cut back after flowering

Pests Can get water lily aphid

Diseases Generally disease free

Advertise here

Did you find the information you were looking for?

RHS members can get exclusive individual advice from the RHS Gardening Advice team.

Join the RHS now