Grevillea robusta - Silk Oak - Evergreen Trees Direct

Grevillea robusta - Evergreen Trees Direct

Grevillea robusta - Silk Oak

$280.00

Tax included. Shipping calculated at checkout.

Size: 40cm/45L

40cm/45L 100L

Current Stock Height Guides

40cm/45L: 1.3m – 1.8m Approx.
100L: 2m – 2.4m Approx.

Height guide disclaimer: Height ranges are approximate only. As living products, plant heights naturally vary between individual plants, batches, and seasons. No guarantee is given that supplied plants will fall within the stated range. If minimum heights are required, you mustconfirm current batch heights with Evergreen Trees Direct prior to purchase. Variation in height is normal and is not grounds for return, refund, replacement, or compensation.

Mature Height & Width

Mature Height: 15m to 30m (approx.)

Mature Width: 10m to 15m

Grevillea robusta - Silk Oak is expected to grow 40cm to 60cm per year (vigorous).

Root Ball Dimensions

Use this as a reference when digging your planting hole. We recommend digging at least 10% wider than the dimensions below to encourage strong root development.

30cm Pot: 33cm (W) × 30cm (D)
40cm/45L Pot: 44cm (W) × 41.5cm (D)
50cm Pot / 70L Pot: 55cm (W) × 41.8cm (D)
100L Bag: 50.6cm (W) × 52.8cm (D)
150L Bag: 66cm (W) × 55cm (D)
200L Bag: 71.5cm (W) × 60.5cm (D)
300L Bag: 88cm (W) × 63.8cm (D)
400L Bag: 99cm (W) × 66cm (D)
500L Bag: 122cm (W) × 66cm (D)
750L Bag: 134cm (W) × 69cm (D)
1000L Bag: 146.3cm (W) × 71.5cm (D)
2000L Bag: 176cm (W) × 82.5cm (D)

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Shipping

Shipping is calculated at checkout based on the pallet space your order occupies in the truck and your delivery location.

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Contact

Have a question or a list to send through to us?

Email: sales@evergreentrees.com.au

Phone: (03) 7042 3318

About Your New Grevillea robusta - Silk Oak

Grevillea robusta carries large golden-orange toothbrush flowers across the whole canopy in spring and early summer, drawing honeyeaters and lorikeets in numbers few other trees manage. Fine fern-like foliage gives it a lightness unusual in a tree of this scale.

The Silk Oak grows to 15 to 30 metres tall and 10 to 15 metres wide at 40 to 60 centimetres per year, forming an upright pyramidal frame when young that broadens with age. It is used for shade, shelter and feature planting on acreage, rural properties and in large civic landscapes.

This Australian native is frost hardy, surviving heavy and frequent frost without damage, and tolerates poor soils and extended dry once established. It grows in full sun to part shade and needs free drainage, along with low-phosphorus feeding like all Proteaceae.

Frequently Asked Questions

About Grevillea robusta

How big does Grevillea robusta grow?

The Silk Oak reaches 15 to 30 metres tall and 10 to 15 metres wide. It is a large tree best suited to acreage, rural properties and parkland rather than small suburban blocks.

How fast does Silk Oak grow?

It grows vigorously at 40 to 60 centimetres per year, and considerably faster in warm frost-free conditions with reliable moisture.

When does Grevillea robusta flower?

Large golden-orange toothbrush flowers appear through spring and into summer, carried heavily across the canopy. They are a major nectar source for honeyeaters and lorikeets.

Is Grevillea robusta an Australian native?

Yes. It is native to the subtropical rainforest margins of eastern Australia and is the largest species in the Grevillea genus.

What feeding does Silk Oak need?

Use only low-phosphorus native fertiliser. Like all Proteaceae, Grevillea robusta is damaged by high-phosphorus formulations, which can kill established trees.

Is Grevillea robusta frost hardy?

Yes, once established it survives heavy and frequent frost without damage. Young trees benefit from protection through their first winter in cold districts.

How far apart should I plant Silk Oak?

Plant 8 to 10 metres apart for a shelterbelt or avenue, and at least 10 metres from buildings and services given its eventual size.

Enriched Planting Mix (AO Certified)

$21.95

Enriched Planting Mix is a certified organic blend of Pure Magic Compost, composted animal manure, gypsum, composted coarse bark and a wetting agent, bagged in 30L. It is built to be dug through existing garden soil at planting time rather than used on its own, and the gypsum is what sets it apart from a plain compost.

Gypsum helps break up heavy clay so water and roots can move through it, while the compost and manure return organic matter and nutrient to tired ground. The coarse bark holds structure and keeps air around the root zone, and the wetting agent keeps moisture in the soil longer after rain or watering.

Use it when planting trees, shrubs, roses, fruit trees and exotic garden plants, particularly into clay. Dig a hole twice the width of the pot and 7 centimetres deeper, then mix roughly one third planting mix through the excavated soil. Spread 7 centimetres of that improved soil in the base before setting the plant in.

Frequently Asked Questions

About Enriched Planting Mix

What is Enriched Planting Mix made from?

It is a blend of Pure Magic Compost, composted animal manure, gypsum, composted coarse bark and a wetting agent. Each part has a job. The compost and manure supply organic matter and nutrient, the gypsum works on clay structure, the bark keeps air around the roots and the wetting agent holds moisture in the soil.

What plants is it suitable for?

It suits exotic garden plants, including roses, ornamental and deciduous trees, fruit trees, shrubs and perennials, and it earns its keep most on heavy clay sites. It is a planting mix rather than a potting mix, so its job is improving soil at planting time. Phosphorus sensitive natives are the one clear exception.

Is it safe for natives?

No, not for the phosphorus sensitive ones. The composted animal manure in this blend lifts phosphorus well above what Proteaceae such as Banksia, Grevillea, Hakea and Protea will tolerate, and the result can be leaf burn, dieback and plant death. Use the Native Potting Mix for those species, or plant them into unimproved local soil.

Is it certified organic?

Yes. It is a certified organic product with no chemical additives, which is why the manure and compost in it are fully composted rather than raw. That makes it sound around fruit trees and vegetable beds, and it means you are adding genuine organic matter to your soil rather than a synthetic conditioner.

How much do I need?

Work on roughly one third planting mix to two thirds of the soil you dug out of the hole. For a shrub out of a 200 millimetre pot that is only a few litres. An advanced tree going into a large hole will take considerably more. Judge the quantity by the volume of the hole rather than the size of the plant.

Can I use it in pots?

It is not a potting mix and should not be used on its own in a container. The blend is designed to be diluted through garden soil, and used straight in a pot it holds too much water and settles badly. For containers, reach for a premium potting mix, or the native mix if you are potting natives.

Does it need to be watered in?

Yes. Water the plant well several hours before you plant it, then water thoroughly again once the hole is backfilled and the soil firmed down. That first deep watering settles the improved soil around the root ball and drives out air pockets. Keep the water up over the first few months while the roots establish.

View full details

Type: Garden Supplies

Enriched Planting Mix (AO Certified)

$21.95

Type: Australian Native

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Uses in my Garden

Feature Tree
Rural Property Planting
Shade Tree
Screening or Privacy

Grevillea robusta - Silk Oak works in an:

Australian Native Garden – celebrates local plants with natural character.
Tropical Garden – lush, leafy planting for a resort-style atmosphere.
Modern Garden – sleek, minimal, and design-led planting.
Low-maintenance Garden – resilient choices for easy care and year-round appeal.

Is Grevillea robusta - Silk Oak Evergreen or Deciduous?

Grevillea robusta - Silk Oak is an Evergreen (foliage year round) Tree

Mature Height & Width

Mature Height: 15m to 30m (approx.)

Mature Width: 10m to 15m

Grevillea robusta - Silk Oak is expected to grow 40cm to 60cm per year (vigorous).

Growth Rate of Grevillea robusta - Silk Oak

Grevillea robusta - Silk Oak is expected to grow 40cm to 60cm per year (vigorous).

They are considered to have a:

Fast Growth Rate

Frost Tolerance & Ideal Climate to plant Grevillea robusta - Silk Oak

Is Grevillea robusta - Silk Oak frost tolerant?

Grevillea robusta - Silk Oak is Frost Hardy – Survives heavy and frequent frost without damage.

Does Grevillea robusta - Silk Oak Flower?

Grevillea robusta produces long, showy, golden-orange toothbrush-shaped flowers from late spring into early summer. These upright clusters sit above the fern-like foliage and create a striking seasonal display that stands out brilliantly against the tree’s deep green canopy.

Does Grevillea robusta - Silk Oak flower?

Yes - Flowers

Flowering Period:

Spring
Summer

Flower Type:

Fluffy

Flower Colour:

Yellow

Is Grevillea robusta - Silk Oak an Australian Native Tree?

Yes

Grevillea robusta - Silk Oak is Native to Native to eastern Australia, where it grows in subtropical and dry rainforests of Queensland and New South Wales.

What is the Wildlife Value of Grevillea robusta - Silk Oak ?

Its nectar-rich flowers attract honeyeaters, lorikeets, native bees and butterflies, making it a powerhouse for pollinators. The large evergreen canopy provides shelter and nesting habitat for birds, while the textured bark supports insects and microfauna that boost biodiversity in native and subtropical gardens.

How much Sunlight does Grevillea robusta - Silk Oak need?

Grevillea robusta - Silk Oak will thrive best in:

Full Sun
Part Shade

Preferred Soil?

Grevillea robusta performs best in well-drained sandy or loam soils and prefers slightly acidic to neutral conditions. It may struggle in heavy clay or poorly drained areas unless improved with organic matter and coarse material to enhance drainage. Keep soil evenly moist during establishment, then transition to deep, occasional watering as the tree matures to support its drought resilience, healthy structure and reliable flowering.

Is Grevillea robusta - Silk Oak Drought Tolerant?

Is Grevillea robusta - Silk Oak Drought tolerant?

As a young tree it requires regular watering, but once established the Silk Oak develops excellent drought tolerance. Naturally adapted to warm, dry and coastal conditions, it maintains vigorous growth and good canopy density with minimal supplementary watering.

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How To Plant Your Grevillea robusta - Silk Oak

Site: Choose a well-drained position in full sun to part shade with room for the canopy to develop.

Soil preparation: Enrich the planting area with quality compost and aged manure for a strong establishment phase.

Hole: Dig twice as wide as the root ball and the same depth.

Planting: Position level with the surrounding soil, backfill gently, firm in, then water deeply to settle the roots.

Recommended Planting Spacing For Your Grevillea robusta - Silk Oak

Feature tree: 3 to 4 metres apart to allow the full canopy and form to develop.

Avenue planting: 3 metres apart for a uniform soft-textured avenue.

Grevillea robusta - Silk Oak is expected to grow 40cm to 60cm per year (vigorous).

Fast Growth Rate

Long Term Care For Your Grevillea robusta - Silk Oak

Watering: Water deeply twice weekly through the first 12 months. Once established, this is drought tolerant and only needs a deep soak during extended dry periods.

Mulching: Apply a 5 to 7 centimetre layer of organic mulch over the root zone, keeping it 5 centimetres clear of the trunk.

Pruning: Minimal pruning required. Light tip prune in late winter to maintain shape, and remove lower branches as the tree grows to develop a clean feature trunk.

Fertilising: Apply a slow-release native blend in early spring and again in autumn. Avoid high-phosphorus formulations as a precaution.

Pest and disease: Hardy against most pests and diseases. Occasional inspection in warm humid conditions is all that's needed.

Planting Your Grevillea robusta - Silk Oak in Different Soil

Grevillea robusta performs best in well-drained sandy loam or loam with a slightly acidic to neutral pH. Adaptable to a wide range of soils when drainage is improved with organic matter.

Sandy soil: Free-draining and ideal. Mulch well to maintain consistent moisture.

Clay soil: Improve drainage with gypsum and organic compost before planting.

Loam: The preferred soil for steady root development and consistent growth.

pH: Slightly acidic to neutral preferred. Mulch with composted leaf litter to maintain levels naturally.

Frequently Asked Questions

Frequently Asked Questions (FAQs):

Q: Can Grevillea robusta tolerate drought?
A: Yes, once established, Grevillea robusta is moderately drought-tolerant, making it suitable for regions with dry spells.

Q: What type of soil does it prefer?
A: Grevillea robusta can thrive in various soil types, including clay and sandy soils, as long as they are well-draining.

Q: Are the orange-red flowers attractive to wildlife?
A: Yes, the vibrant orange-red flowers of Grevillea robusta are known to attract birds and pollinators, adding to the tree's appeal in the garden.