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Conservatory GreenhouseBogsHerbaceous PerennialAquatic

Canna 'Ra'
  • RHS AGM

water canna 'Ra'

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

© RHS
© RHS
© RHS
© RHS
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Size
Ultimate height
1.5–2.5 metres
Time to ultimate height
1–2 years
Ultimate spread
0.5–1 metres
Growing conditions
Loam
Moisture
Poorly–drained, Moist but well–drained
pH
Acid, Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Grey Silver Green
Summer Yellow Grey Silver Green
Autumn Yellow Grey Silver Green
Winter
Position
  • Full sun
Aspect

West–facing or South–facing

Exposure
Sheltered
Hardiness
H3
Botanical details
Family
Cannaceae
Native to the UK
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

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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

Get involved

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