Hydrangea Cloud Nine ('Tmhy18-1')

RHS Plant Profile
hydrangea [Cloud Nine]

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Synonyms

Hydrangea 'Tmhy18-1'
Hydrangea 'Cloud Nine'
Hydrangea '18/1'
Hydrangea 'Hyd 18/1'
Hydrangea Princess Bride

Shrubs

A deciduous shrub to 1.2m high, with a neat habit and narrowly ovate, serrated green leaves. In summer, large, loose lace-cap sterile flowers emerge lime green, fading to white, sometimes with a pinkish hue as they mature

Position

Partial shade

Soil Types

Clay, Loam

Max Height

1-1.5 metres

Max Spread

1-1.5 metres

Size

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

Growing Conditions

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

Position

Partial shade
Aspect
East–facing or North–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
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
Trade

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 in early summer, or by hardwood cuttings in winter

Suggested planting locations and garden types

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

Pruning

See pruning group 4 (hydrangeas)

Pests

May be susceptible to aphids, capsid bug, red spider mite, stem and bulb eelworm, vine weevil and scale insects

Diseases

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