Hydrangea macrophylla 'Altona' (H)

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hydrangea 'Altona'

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hydrangea 'Altona' RHS 2001
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Shrubs
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A small deciduous shrub with broadly ovate leaves. Hortensia-type with large rose-red sterile florets, turning to green then deep red in autumn. Blues well on acid soils

Position

Full sun, Partial shade

Soil Types

Clay, Loam, Sand

Max Height

0.5-1 metres

Max Spread

1-1.5 metres

Size

Time to Maturity
5–10 years
Max Spread
1-1.5 metres
Max Height
0.5-1 metres

Growing Conditions

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

Position

Full sun Partial shade
Aspect
South–facing or North–facing or West–facing or East–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)
H5

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Hydrangeaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Bushy
Potentially harmful
Skin allergen. Wear gloves and other protective equipment when handling. Pets (dogs, cats): Harmful if eaten. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus
Hydrangea can be deciduous or evergreen shrubs, or self-clinging climbers, with flowers in clusters usually comprising both small fertile and more showy sterile flowers; often good autumn colour
Name Status
Accepted
Horticultural Group

Horticultural Classification Codes

Horticultural Classification Codes are often given to genera which have a large number of species or cultivars. They are used to categorise cultivated plants based on specific, shared characteristics such as shape, colour, size or flowering time, and can be displayed as letters or numbers

For example:
Dahlia ‘Sunset Kate (Sin) = Single flower
Rosa ‘Marigold’ (HT) = Hybrid Tea

Hortensia hydrangeas (also known as mopheads) are compact bushy deciduous shrubs with broadly ovate leaves and rounded flower clusters composed almost entirely of showy sterile flowers

How to Grow

Cultivation

Grow in any moist but well-drained soil in partial shade or grow in sun if soil remains reliably moist. Improve chalky soils with organic matter to support good growth. See shrubby hydrangea cultivation for further advice

Propagation

Propagate by softwood cuttings

Suggested planting locations and garden types

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

Pruning

See pruning group 4 for further advice and video guide

Pests

May be susceptible to aphids, scale insects, vine weevils and capsid bug

Diseases

May be susceptible to a leaf spot, powdery mildews, grey moulds (Botrytis) and honey fungus (rarely)