Grevillea Robusta or Silk Oak Tree

Grevillea Robusta or Silk Oak is an RHS AGM-winning, fast-growing ornamental shrub or tree with stunning golden-orange flowers and fern-like foliage. It’s a handsome specimen tree for mixed borders and low-maintenance gardens.

Grevillea Robusta is better known as Australia’s Silk Oak. It grows natively on the east coast of Australia in dry rainforest environments and although its name ‘Robusta’ is Latin for strong or ‘oak-like’ it’s not a species of oak.

Silk Oak is a handsome ornamental tree that is evergreen in its native environment, but it’s likely to lose some of its foliage in the UK over winter and reveal its dark grey peeling trunk. Its leaves reach 30 centimetres in length and resemble mid-green fern foliage. They have silvery undersides that glitter and create lots of movement in the breeze. During summer, mature Silk Oak produces a really stunning display of golden-orange flower spikes that can reach 12 centimetres and attract lots of pollinators.

This is an attractive shrub or tree that fills an outside space with colour and movement most months of the year in mild coastal areas.

Height And Spread of Grevillea Robusta
Mature Silk Oak can reach 20 metres in height and eight metres in spread.

How Hardy Is Grevillea Robusta
It’s hardy in UK winters, but can be susceptible to hard frost. It copes with drought once established and best suits sheltered or mild coastal gardens.

How To Use Grevillea Robusta
This is an attractive shrub or tree for mixed borders, tropical, Mediterranean, and low-maintenance gardens. It attracts plenty of wildlife and brings colour throughout the year. If you’re looking for an unusual tree with a stunning flower display, then Silk Oak is a great choice.

How To Care For Grevillea Robusta
Plant Silk Oak in acidic to neutral soil in west or south-facing positions that catch the full sun. It’s best to avoid frost pockets and exposed areas because it’s a dry rainforest tree that needs warmth to thrive.
If you’re letting Silk Oak grow into a large tree then only prune wayward branches if it’s necessary after flowering. A more thorough prune may be required to restrict its size to a shrub.
Water it well until you can see new growth and apply a thick layer of acidic pine, bracken, or ericaceous mulch to the roots in early spring.