• AGM plants

    AGM plants have been through a rigourous 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

Spiraea nipponica 'Snowmound'

Tosa spirea 'Snowmound'

AGM plants

AGM plants have been through a rigourous 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
Tosa spirea 'Snowmound'

© � RHS 2002

  • Other common names Tosa spirea 'Snowmound'

  • Synonyms Spiraea nipponica Maxim. var. tosaensis misapplied

  • Genus Spiraea are deciduous shrubs, sometimes suckering, with simple leaves and short racemes, panicles or corymbs of small, 5-petalled white or pink flowers in spring or summer

  • Family Rosaceae / Rosaceae

  • Species 'Snowmound' is a spreading medium-sized deciduous shrub with arching branches bearing small obovate leaves and short lateral shoots ending in rounded clusters, to 4cm in width, of small white flowers

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)
    Old hardiness ratings

    While we update our systems with the new hardiness ratings you may still see old hardiness ratings in your search results. These are denoted as 'Old'.

    • H1 - Requires heated glass
    • H2 - Requires unheated glass
    • H3 - Hardy outside in some regions of the UK
    • H4 - Hardy throughout the UK
    • H1 + H3 - Requires heated glass but may be grown outside in summer

    For full details of the hardiness ratings see

    see more

    H6

Colour

Sunlight

  • Full Sun

  • Partial Shade

  • Aspect North-facing or East-facing or South-facing or West-facing

  • Exposure Sheltered or Exposed

Soil

  • Chalk

    Loam

  • Chalk

    Chalk

  • Chalk

    Sand

  • MoistureWell-drained, Moist but well-drained

  • SoilLoam, Chalk, Sand

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height

    1.5-2.5 metres

  • Ultimate spread

    1.5-2.5 metres

  • Time to ultimate height

    10-20 years

How to grow

Cultivation Easy to grow in most moist soils, tolerant of all but the most extreme conditions. Especially suitable for mixed borders

Propagation Propagate by softwood cuttings in summer

Suggested planting locations and garden types Low Maintenance Banks and Slopes Flower borders and beds Cottage & Informal Garden

How to care

Pruning Pruning group 2. If overgrown, can be renovated by cutting back hard immediately after flowering

Pests Generally pest free

Diseases Generally disease free

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