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Grevillea robusta AGM

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© RHS 2002

Characteristics

Plant type

Bedding, Conservatory/Greenhouse or Tree

Habit

Bushy

Toxicity

Resilience

Hardiness

H1c (heated greenhouse - warm temperate)

Colour

Flower

Yellow in Spring and Summer

Foliage

Green in Autumn, Spring, Summer and Winter

Size

Ultimate height

Higher than 12 metres

Ultimate spread

4-8 metres

Time to ultimate height

20-50 years


Preferred common name

silky oak

Family

Proteaceae


Grevillea can be evergreen shrubs or trees, with alternate, simple or pinnately divided leaves and petal-less flowers consisting of a colourful calyx tube with protruding style, borne in racemes or panicles

G. robusta is a fast-growing evergreen tree to 20m or more, but is usually grown as an annual for foliage effect making a bushy shrub to 3m. Olive-green, fern-like leaves to 30cm in length, paler beneath. Racemes of tubular yellow flowers are produced only by mature plants

Other common names

  • silk oak
  • silky-bark oak

How to grow

Sunlight

  • Full sun

Aspect

  • South-facing or West-facing
  • Sheltered

Cultivation

Grow outdoors in acid to neutral well-drained soil in a frost-free area or as part of a summer bedding scheme. Grow under glass in lime-free compost with added grit in full light. May need restrictive pruning under glass

Soil

  • Moist but well-drained or Well-drained
  • Acid or Neutral
  • Loam or Sand

Propagation

Propagate by seed, semi-hardwood cuttings or graft

Suggested planting locations and garden types

Patio/Container Plants


How to care

Pruning

Pruning group 1 outdoors, but more rigorous pruning may be necessary indoors to restrict size

Pests

Generally pest free

Diseases

Generally disease free