Plant Guide

Grevillea robusta

silky oak, silk oak, Australian silver oak

Large evergreen tree in the Proteaceae family, native to Australia, with a pyramidal to oval crown and fern-like foliage. Golden orange flowers, arranged in 8-16 cm long, bottlebrush-like racemes, on mature trees in spring-summer. Mid to dark green, divided leaves to about 30 cm long, with silky, silvery white undersides. Widely planted for timber, shelter, and ornamental purposes. Naturalised in many regions of the world. Has become invasive in some areas, such as Hawaii, Brazil, South Africa, and parts of Australlia, where it competes with the indigenous vegetation. Contains toxins. Leaves may cause skin irritation, and can inhibit establishment of other plant species. Attracts nectar-feeding birds.

Prefers a sunny position in any well-drained, slightly acidic soil. Tolerates rather poor soils. Frost-tender when young, hardy to about -8 0C when mature. Reasonably drought tolerant once established. Suitable for coastal areas with protection from persistent, strong winds.

Beautiful tree when in flower, but needs plenty of space. It is not a tidy tree and produces quite a large amount of litter, in particular in winter just before the new leaves emerge. Young plants can be used as indoor foliage plants.

Type of plant

Tree - Evergreen

Size

15-35 m tall

Landscape Use

specimen tree, flower display

Specifications

  • Temperature: Half hardy
  • Light: High
  • Moisture: Low Medium
  • Soil: Light Medium Heavy
  • Wind tolerance: Average
  • Coastal tolerance: High