Southern Silky-oak
Grevillea robusta · Proteaceae
📷 MargaretRDonald · CC BY-SA 4.0
The gardener's calendar
In autumn, ease off feeding and take the chance to clean up around southern silky-oak and prepare for winter.
ID card
- Foliage
- Evergreen, finely divided and feathery
- Flowering
- May to July, golden yellow flowers in spikes
- Adult size
- 10 m in height, upright and slender form
- Growth
- Fast to moderate
- Hardiness
- Sensitive to cold, frost-tender below 5°C
- Origin
- Eastern Australia (New South Wales, Queensland)
- Soil type
- Well-drained, tolerates poor and sandy soils
✓ Taxonomy verifiedSource: AI estimate · hardiness: reliability medium.
Expert tips
The key tip
Big sun-lover that needs well-drained soil; once it's established, dial back on regular watering.
The common mistake
Treating it like a typical young shrub by watering constantly—it gets dependent and struggles with independence when you finally stop.
The pro's trick
Pinch back the top at 60-80 cm during the first year to force nice basal branching and a sturdier shape.
Care
Watering
Once established, Grevillea robusta tolerates drought well. Water regularly during the first year after planting to ensure root establishment. In temperate or continental climates, gradually reduce watering, except during prolonged dry spells. Avoid waterlogging, which promotes root rot.
Exposure
Plant the silk oak in full sun for optimal growth and generous flowering. It also tolerates partial shade, though flowering will be less abundant. Protect it from cold and drying winds, particularly in exposed areas.
Pruning and training
Remove dead or damaged branches after frost. Light formative pruning during the first few years helps structure the form. Generally, little pruning is needed; the plant naturally develops an upright and airy silhouette.
Fertilizer
Grevillea robusta is not demanding in terms of nutrients. An annual application of balanced fertilizer in spring is sufficient for container specimens. In well-prepared garden soil, additional fertilizer is generally unnecessary.
Soil and drainage
Soil must be well-drained, even poor. Compacted or clay soils promote root rot. Improve drainage by adding coarse sand or gravel when planting. This plant thrives in light and aerated substrates.
Diseases and pests
In overly humid conditions, watch for root rot and fungal diseases. Spider mites can infest indoor or greenhouse specimens. Promote air circulation to prevent fungal attacks. Check root condition regularly, especially in pot cultivation.
Did you know?
Grevillea robusta is called 'silk oak' not for its resemblance to oak, but for the silky, delicate texture of its feathery foliage. In Australia, it is an iconic plant of the southeast coast, long used in reforestation and agroforestry to stabilize soils and create windbreaks, before conquering European and Mediterranean gardens as a spectacular ornamental tree.
Where to buy it
Best planted in autumn so the roots settle in before summer, or in early spring once the frost has passed. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, October, November.
Add this plant to my garden →Plants from the same family
- Juniper-leaf grevilleaGrevillea juniperina
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- Silver banksiaBanksia marginata
- Persoonia linearisPersoonia linearis
- Hairpin banksiaBanksia spinulosa
Tips generated and checked by Viridia — adapt them to your local climate.