• 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

Acorus gramineus 'Ogon' (v)

slender sweet flag 'Ogon'

slender sweet flag 'Ogon'

© RHS

  • Other common names slender sweet flag 'Ogon'

  • Family Acoraceae

  • Genus Acorus are deciduous or semi-evergreen, moisture-loving rhizomatous perennials forming tufts of linear or sword-shaped leaves, with insignificant spike-like flowers borne near the tips of central leaf-like stems

  • Details 'Ogon' is a compact deciduous grass-like perennial forming a clump to 30cm tall, with narrow, bright yellow leaves, lightly striped with yellowish-green

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)

    H6

Colour

Sunlight

  • Full Sun

  • Aspect South-facing or West-facing

  • Exposure Sheltered

Soil

  • Clay

    Clay

  • Chalk

    Chalk

  • Loam

    Loam

  • MoisturePoorly-drained

  • SoilClay, Chalk, Loam

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height 0.1-0.5 metres

  • Ultimate spread 0.1-0.5 metres

  • Time to ultimate height 5-10 years

How to grow

Cultivation Easy to grow in wet or very moist fertile soils. Can be planted in baskets in shallow water. It also makes a useful aquarium plant but is short-lived where water temperatures exceed 22°C for long periods. Divide every few years to prevent congestion

Propagation Propagate by rhizome division at the beginning of the growing season. Pot up and plant out only when fully established

Suggested planting locations and garden types Low Maintenance Cottage & Informal Garden

How to care

Pruning Cut back after flowering

Pests Generally pest free

Diseases Generally disease free

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