Agapanthus 'Blue Steel'

RHS Plant Profile
African lily 'Blue Steel'

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Herbaceous Perennial
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A deciduous, clump-forming herbaceous perennial needing winter protection, with mid-green strap-like leaves and upright stems producing panicles of nodding, pale mauve-light blue flowers in summer

Position

Full sun

Soil Types

Chalk, Loam, Sand

Max Height

0.5-1 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
2–5 years
Max Spread
0.1-0.5 metres
Max Height
0.5-1 metres

Growing Conditions

Chalk Loam Sand
Moisture
Moist but well–drained or 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)
H4

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Amaryllidaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Clump forming
Potentially harmful
Humans/Pets (dogs, cats): harmful if eaten. Wear gloves and other protective equipment when handling. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus
Agapanthus are clump-forming perennials with narrowly strap-shaped leaves, evergreen in some species, and erect stems bearing umbels of funnel-shaped blue or white flowers
Name Status
Accepted

How to Grow

Cultivation

Grow in fertile, moist but well-drained soil in full sun. In cold areas mulch hardy hybrids in winter. In containers, grow in peat-free, loam-based compost. Apply a balanced liquid feed monthly from spring until flowering. For more information see agapanthus cultivation. May need winter protection

Propagation

Propagate by seed when ripe in autumn or spring and keep seedlings in cold frame overwinter - they will flower in 2-3years or propagate by division every three to four years in spring

Suggested planting locations and garden types

  • City and courtyard gardens
  • Cottage and informal garden
  • Patio and container plants
  • Flower borders and beds

Pruning

Remove leaves as they naturally die back, deadhead complete flower stems as flowers go over

Pests

May be susceptible to slugs and snails and agapanthus gall midge

Diseases

May be susceptible to a virus