Silky Oak (Grevillea robusta)

Silky Oak

Grevillea robusta

A fast-growing evergreen tree celebrated for its fern-like foliage and striking golden-orange toothbrush-like blooms. Other names: Australian Silky Oak.

Requires full sun for optimal growth and flowering.
1/week
Easy
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Plant Needs

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Sunlight Requires full sun for optimal growth and flowering.
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Watering Highly drought-tolerant once established; prefers deep, infrequent watering.
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Temperature Thrives in warm climates; young plants are frost-sensitive but mature trees can tolerate light frosts.
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Characteristics

  • Leaves: Fern-like, bipinnatifid, dark green above and silvery-silky below, 15-30 cm long;
  • Flowers: Golden-orange to yellow, arranged in one-sided racemes (toothbrush-like), lacking petals but with prominent long styles;
  • Bark: Dark grey, furrowed and fissured in older trees;
  • Fruit: A leathery, boat-shaped follicle containing winged seeds.
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Care Guide

Watering

Water deeply once a week during active growth and dry spells.

Fertilization

Apply a low-phosphorus or phosphorus-free fertilizer.. Proteaceae plants have specialized roots and are easily killed by standard high-phosphorus fertilizers.

Used Coffee Grounds:Lightly scatter used coffee grounds around the base of the tree. This provides a gentle nitrogen boost and helps maintain soil acidity without introducing harmful levels of phosphorus. Avoid thick layers to prevent mold.
Pruning
  • Prune when young to establish a strong central leader and structural framework;
  • Remove dead, damaged, or crossing branches in late winter;
  • Avoid heavy pruning of mature trees as it can ruin their natural pyramidal shape;
  • Wear gloves and long sleeves when pruning to prevent contact dermatitis from the sap.
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Toxicity

Warning: this plant may be toxic.

Pets & Humans

Pets: May cause mild gastrointestinal upset if ingested or skin irritation upon contact.

Humans: Sap and foliage may cause contact dermatitis in sensitive individuals.

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Garden Uses & Culture

Culture: Introduced to Europe and the Americas in the 19th century, it became a popular Victorian-era indoor foliage plant before its massive outdoor size was fully appreciated. It is now a common street tree in warm-climate cities globally.

Usage: - **Ornamental**: Specimen tree in large gardens and parks; - **Timber**: Wood is prized for cabinet making and furniture, historically used for window frames; - **Ecological**: Rich nectar source attracting bees and nectar-feeding birds.