About
Grevillea robusta, the silky oak, is a fast-growing evergreen tree reaching 20 m or more in the wild but often grown as a foliage annual making a bushy shrub to 3 m. It produces fern-like, olive-green leaves to 30 cm long, paler beneath, and � on mature plants � racemes of tubular, yellow-orange flowers. A dramatic foliage plant for a heated greenhouse, large conservatory or frost-free garden.
About the genus
Grevillea are evergreen shrubs and trees from Australia and the Pacific with alternate, simple or pinnately divided leaves and petal-less flowers in which the colourful calyx tube splits to reveal a protruding style, borne in racemes or panicles. Popular and ornamental plants for mild, sunny gardens.
Growing conditions
SunlightFull sun
Soil typeLoam, Sand
Soil pHAcid, Neutral
Soil moistureMoist but well-drained, Well-drained
AspectWest-facing, South-facing
ExposureSheltered
UK hardinessH2
Plant details
Plant typeBedding, Conservatory Greenhouse, Trees
HabitBushy
FoliageEvergreen
HeightHigher than 12 metres
Spread4-8 metres
Time to full height20-50 years
Suggested usesPatio and container plants
Native toE Australia
ToxicitySkin 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
Care notes
CultivationGrow 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
PruningPruning group 1 outdoors, but more rigorous pruning may be necessary indoors to restrict size
PropagationPropagate by seed, semi-hardwood cuttings or graft
Pest resistanceGenerally pest-free
Disease resistanceMay be susceptible to honey fungus (rarely)