Canna 'Black Knight'

RHS Plant Profile
canna 'Black Knight'

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canna 'Black Knight' visionspictures.com
Herbaceous Perennial
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Erect clump-forming perennial to 1.8m tall, with large, bronze to bluish-purple leaves, and very dark red flowers to 8cm across from midsummer to autumn. A good plant for a tropical border

Position

Full sun

Soil Types

Loam, Sand

Max Height

1.5-2.5 metres

Max Spread

1-1.5 metres

Size

Time to Maturity
2–5 years
Max Spread
1-1.5 metres
Max Height
1.5-2.5 metres

Growing Conditions

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

Position

Full sun
Aspect
South–facing or West–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
Columnar upright
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

Grow in a sheltered site with full sun. Water freely in dry spells and apply a balanced liquid feed monthly. In cold regions, lift the rhizomes in autumn once frost has blackened the foliage and store in barely moist compost in frost-free conditions. In areas that are frost-free or almost so, leave in situ and protect with a deep dry mulch. See canna cultivation for further information

Propagation

Propagate by division of rhizomes in spring

Suggested planting locations and garden types

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

Pruning

No pruning necessary, deadhead flowers to prolong flowering

Pests

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

Diseases

May be susceptible to Canna viruses