Polemonium 'Sapphire'

RHS Plant Profile
Jacob's ladder 'Sapphire'

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Herbaceous Perennial

A bushy, clump-forming perennial to around 45cm high, forming a low mound of long, pinnate leaves, divided into 10-20 elliptic leaflets held in offset pairs. Arching sprays of nodding blue flowers are produced in late spring

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

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

Growing Conditions

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

Position

Full sun Partial shade
Aspect
East–facing or South–facing or West–facing
Exposure
Exposed or 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)
H7

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Polemoniaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Bushy, Clump forming
Genus
Polemonium can be annuals or herbaceous perennials or upright or spreading habit, with pinnate leaves and usually clustered, tubular, bell, or funnel-shaped flowers
Name Status
Accepted

How to Grow

Cultivation

Grow in fertile, moist but well-drained soil, will benefit from some shade where summers are hot

Propagation

Propagate by division in spring

Suggested planting locations and garden types

  • Cottage and informal garden
  • Patio and container plants
  • Flower borders and beds

Pruning

Deadhead regularly to encourage new flowers

Pests

Generally pest-free

Diseases

May be susceptible to powdery mildews