Canna 'Ra'

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water canna 'Ra'

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water canna 'Ra' RHS
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Conservatory Greenhouse Bogs Herbaceous Perennial Aquatic
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Very large perennial suited to aquatic and bog gardens, growing into a spreading clump 1.8m or more tall, with narrow grey-green leaves, and bearing large lemon-yellow flowers above tall stems, from midsummer to autumn

Position

Full sun

Soil Types

Loam

Max Height

1.5-2.5 metres

Max Spread

0.5-1 metres

Size

Time to Maturity
1–2 years
Max Spread
0.5-1 metres
Max Height
1.5-2.5 metres

Growing Conditions

Loam
Moisture
Poorly–drained or Moist but well–drained
pH
Acid or Alkaline or Neutral

Position

Full sun
Aspect
West–facing or South–facing
Exposure
Sheltered
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)
H3

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Cannaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Clump forming
Genus
Canna are rhizomatous herbaceous perennials with erect stems bearing ovate leaves, with showy flowers with showy petal-like staminodes and small, coloured petals and sepals, borne in racemes or panicles in summer and autumn
Name Status
Accepted

How to Grow

Cultivation

In summer, water cannas (often bred from Canna glauca) can be placed in containers in ponds with no more than 15cm (6in) of water over the roots. They are also suitable for well-watered borders or conservatories where potted plants can be stood in deep saucers of water. Before autumn frosts, bring plants from outdoors into a frost-free greenhouse or conservatory. Keep the pots moist but not saturated. In April, increase temperatures and plant the sprouted plants out in late May when the risk of frost has passed

Propagation

Propagate by division of rhizomes in spring

Suggested planting locations and garden types

  • Architectural
  • Patio and container plants
  • City and courtyard gardens
  • Coastal
  • Cottage and informal garden
  • Sub-tropical
  • Flower borders and beds
  • Conservatory and greenhouse

Pruning

Deadhead regularly to promote flowering, allow to die back naturally in autumn

Pests

May be susceptible to glasshouse red spider mite, aphids, slugs and caterpillars

Diseases

May be susceptible to canna viruses