How to Grow Australian Grevillea
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Australian Grevillea
Grevillea robusta
treeGrevillea robusta, commonly known as the Silky Oak, is a fast-growing Australian native tree prized for its feathery, fern-like foliage and striking orange-red bottlebrush-like flowers. It can reach 30-50 feet in height and serves as an excellent shade tree, ornamental, and timber source. This evergreen is popular in warm climates both as a landscape specimen and indoor potted plant in temperate regions.
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Example Australian Grevillea timeline · Pittsburgh, PA (Zone 6b)
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Plant Australian Grevillea
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 Australian Grevillea
Late summer into fallBefore the first fall frost (≈ Nov 8)
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Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in USDA zones 9b-11; can be grown indoors in cooler climates
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Get my Australian Grevillea timeline →Growth Stages
Germination & Seedling
3-4 weeksSeeds sprout within 2-3 weeks showing cotyledons and initial feathery leaf development
Keep soil consistently moist but not waterlogged. Provide bright indirect light. Maintain warmth (70-75°F). Use seed-raising mix with excellent drainage.
Juvenile Growth
1-2 yearsYoung plant develops multiple stems and increasingly complex fern-like foliage. Growth is vigorous.
Harden off and transplant to larger containers or ground. Begin pruning to shape form. Reduce watering frequency as plant matures. Fertilize sparingly with low-phosphorus fertilizer.
Vegetative Development
2-3 yearsTree establishes strong root system and woody stems. Foliage becomes denser. May reach 15-25 feet.
Support with stakes if in container or windy location. Reduce fertilizer inputs. Ensure excellent drainage. Prune to remove crossed or diseased branches.
Flowering & Maturity
4-8 weeks per flowering season; spring to early summerAt 3-5 years, the tree produces distinctive orange-red bottlebrush flower clusters along branches. Flowers attract birds and insects.
Maintain good air circulation to prevent fungal issues. Deadhead spent flowers if desired. Continue moderate watering during dry spells. Minimal fertilizer needed.
Seed Production
6-12 monthsFlowers transition to woody seedpods containing winged seeds that persist on the tree.
Allow pods to mature and dry for 6-12 months before collecting seeds if propagation is desired. Pods may be left on tree as they add ornamental interest.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Inspect regularly; spray with horticultural oil in spring; prune heavily infested branches; improve air circulation
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Increase humidity; spray with water; use miticide if severe; ensure adequate moisture during hot periods
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Remove with alcohol-soaked cotton swab; spray with insecticidal soap; improve air circulation
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Yellow sticky traps; spray undersides of leaves with neem oil; encourage natural predators
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Ensure excellent soil drainage; avoid overwatering; use well-draining potting mix; remove affected plants
Uses
Timber & Woodworking
CraftGrevillea robusta produces light, fine-grained timber used for furniture, veneers, and interior finishing. The wood takes stain well and is valued for its decorative appearance. [source]
Nectar Source for Birds
WildlifeThe abundant orange-red flowers are highly attractive to honeyeaters, lorikeets, and other nectarivorous birds, making Grevillea an excellent addition to bird-friendly gardens. [source]
Ornamental Shade Tree
HouseholdThe feathery, fern-like foliage and striking flowers make Grevillea an attractive landscape specimen, often used as a fast-growing shade tree in warm-climate gardens and as a decorative potted plant indoors. [source]
Cut Flowers
CraftThe distinctive bottlebrush flower clusters are long-lasting in floral arrangements, providing unique texture and warm orange-red coloring to bouquets and displays. [source]
Indoor Container Plant
HouseholdYoung Grevilleas can be cultivated indoors in containers in temperate climates, providing exotic foliage and flowers as houseplants, though they require bright light and excellent drainage. [source]
Harvest Tips
Grevillea is not harvested for food. For timber, trees are typically harvested at 10-15 years of age. Seeds can be collected from mature seedpods in late summer or fall; allow pods to dry on tree, then extract seeds. Flowers may be cut for ornamental arrangements while in full bloom.
Fun Facts
- 🌱 Grevillea robusta is named after Charles Francis Greville (1749-1809), a British patron of botany, and the Latin 'robusta' references its robust, vigorous growth habit.
- 🌱 The tree is native to subtropical rainforests of northeastern Australia and has been introduced worldwide as a timber and ornamental tree, becoming naturalized in Mediterranean climates.
- 🌱 Grevillea flowers produce copious amounts of nectar and are pollinated primarily by honeyeaters and other birds; a single mature tree can attract dozens of bird species to the garden.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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