Magnolia 'Sir Harold Hillier'

RHS Plant Profile
magnolia 'Sir Harold Hillier'

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Synonyms

Magnolia campbellii (Alba Group) 'Sir Harold Hillier'

Trees
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Small deciduous tree to about 8m in height, with broad mid-green leaves, and bearing large, beautifully-formed, goblet-shaped, white flowers up to 30cm across produced in early to mid-spring

Position

Full sun, Partial shade

Soil Types

Clay, Loam, Sand

Max Height

4-8 metres

Max Spread

4-8 metres

Size

Time to Maturity
10–20 years
Max Spread
4-8 metres
Max Height
4-8 metres

Growing Conditions

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

Position

Full sun Partial shade
Aspect
East–facing or 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)
H5

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Magnoliaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Spreading branched
Genus
Magnolia can be deciduous or evergreen trees or shrubs, with large, showy, often fragrant flowers, often opening before the leaves, and sometimes followed by colourful cone-like fruit
Name Status
Accepted

How to Grow

Cultivation

Grow in moist but well-drained neutral to acid soil in full sun or partial shade with shelter from cold winds. Flowers may be damaged by late frosts. See magnolia cultivation for further advice

Propagation

Propagate by softwood cuttings from late spring to early summer or semi-ripe cuttings from late summer to autumn

Suggested planting locations and garden types

  • Architectural
  • Cottage and informal garden

Pruning

Minimal pruning required, see magnolia pruning. Deciduous magnolias should only be pruned between midsummer and early autumn

Pests

May be susceptible to scale insects, horse chestnut scale and capsid bug

Diseases

May be susceptible to coral spot, phytophthora, grey moulds, honey fungus, a virus or fungal leaf spot