How to Grow Silky Oak
Silky Oak
Grevillea robusta
treeSilky Oak is a fast-growing, evergreen Australian tree prized for its feathery, fern-like foliage and showy golden-yellow flowers. It reaches 30-40 feet tall and is popular as an ornamental tree in warm climates, also valued as a houseplant in cooler regions. The tree produces abundant nectar-rich flowers that attract birds and pollinators.
When should you plant Silky Oak in your zone?
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Example Silky Oak timeline · Pittsburgh, PA (Zone 6b)
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Plant Silky Oak
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Silky Oak
Late summer into fallBefore the first fall frost (≈ Nov 8)
Sample dates for Pittsburgh, PA. Sign up to get exact Silky Oak dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 9b-11, tolerating brief freezes in zone 9b but preferring zone 10 and warmer
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Get my Silky Oak timeline →Growth Stages
Seedling
3-4 weeksTiny seedlings with first true leaves appearing, delicate and fern-like
Keep soil consistently moist but not waterlogged. Provide bright, indirect light. Protect from drafts and temperature fluctuations. Thin seedlings if crowded.
Vegetative Growth
6-18 monthsRapid expansion of feathery, bipinnate foliage; plant develops strong central stem and branching structure
Maintain moderate watering. Apply balanced fertilizer monthly during growing season. Stake if needed for support. Prune to encourage bushiness.
Juvenile to Maturity
1-3 yearsPlant fills out with increasingly dense, fern-like foliage; reaches 8-15 feet in a few years
Reduce fertilizer frequency (quarterly). Water deeply but allow soil to dry between waterings. Prune branches to shape tree and encourage fuller form.
Flowering
8-12 weeks (spring through early summer in most climates)Golden-yellow, brush-like flower clusters (4-6 inches long) appear along branches, highly ornamental and fragrant
Ensure full sun exposure for maximum flowering. Maintain consistent watering during bloom. Deadhead spent flowers to encourage prolonged blooming.
Seed Production & Maturity
Ongoing (seasonal)After flowering, small woody seed pods develop and mature over several months
Allow pods to dry on tree for seed harvest if desired. Collect pods in late summer/fall. Maintain tree health with moderate watering and annual fertilizing.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Spray with water to dislodge; use neem oil or horticultural oil if infestation is severe. Increase humidity around plant.
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Prune heavily infested branches. Apply horticultural oil or insecticidal soap in early spring. Monitor for repeat infestations.
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Remove with rubbing alcohol on a cotton swab for small infestations. Use neem oil or insecticidal soap for larger populations.
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Ensure excellent drainage; avoid overwatering. Remove affected roots and repot in fresh, sterile soil. Treat with fungicide if necessary.
Uses
Honey Production
CulinarySilky Oak flowers are an excellent nectar source for beekeeping, producing aromatic, golden honey with distinctive flavor. [source]
Nectar for Birds & Pollinators
WildlifeThe abundant golden flowers attract native birds, especially hummingbirds and honeyeaters, as well as beneficial insects and butterflies. [source]
Ornamental Indoor Houseplant
HouseholdIn cooler climates, Silky Oak is grown as an attractive tropical houseplant, valued for its delicate, fern-like foliage and elegant form. [source]
Cut Flowers & Arrangements
CraftThe striking golden flower spikes are prized by florists for fresh and dried floral arrangements, lasting well when cut. [source]
Traditional Indigenous Uses
MedicinalIn Aboriginal Australian medicine, various Grevillea species have been used traditionally; Silky Oak bark and leaves may have antimicrobial properties. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Silky Oak is grown for ornament rather than harvest. To collect seeds, allow seed pods to dry on the tree and turn brown (typically 4-6 months after flowering). Harvest pods in late summer/fall, dry indoors for 2-3 weeks, then extract seeds. For cut flowers, harvest flower spikes in early morning when they are fully colored; they last 1-2 weeks in a vase.
Fun Facts
- 🌱 Silky Oak is native to northeast Australia (Queensland and northern New South Wales) and has been widely cultivated worldwide since the 19th century, becoming naturalized in some warm regions.
- 🌱 The feathery compound leaves of Silky Oak resemble those of oak trees, hence its common name, though it is not a true oak—it belongs to the Proteaceae family (which includes banksias, waratahs, and proteas).
- 🌱 Silky Oak wood is lightweight, fine-textured, and beautiful, historically valued for fine woodworking, furniture, and veneer; it is also used as a pulpwood.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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