Grevillea robusta

RHS Plant Profile
silky oak

Other common names

silk oak, silky-bark oak

Award of Garden Merit
Bedding Conservatory Greenhouse Trees

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

Position

Full sun

Soil Types

Loam, Sand

Max Height

Higher than 12 metres

Max Spread

4-8 metres

Size

Time to Maturity
20–50 years
Max Spread
4-8 metres
Max Height
Higher than 12 metres

Growing Conditions

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

Position

Full sun
Aspect
West–facing or South–facing
Exposure
Sheltered
Hardiness
H2

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Proteaceae
Native to GB/Ireland
No
Foliage
Evergreen
Habit
Bushy
Potentially harmful
Skin irritant/allergen. Wear gloves and other protective equipment when handling Pets: Skin irritant/allergen. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus
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
Name Status
Correct
Plant Range
E Australia

How to Grow

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

Propagation

Propagate by seed, semi-hardwood cuttings or graft

Suggested planting locations and garden types

  • Patio and container plants

Pruning

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

Pests

Generally pest-free

Diseases

May be susceptible to honey fungus (rarely)