Silky Oak Grevillea robusta

Silky oak makes a tall, straight tree with a narrow crown when young, gaining height quickly, and it will pass power lines and dwarf a small block long before it slows down. The foliage carries it outside flowering, finely divided and fern like, dark green above with a silvery grey reverse that shows in any wind. In spring the canopy fills with one sided golden orange racemes, the familiar toothbrush shape, and lorikeets work them noisily. It belongs on acreage, in windbreaks and in large native plantings.

Room, wind and the mistake that cannot be undone

Its home range is coastal and near coastal Queensland and northern New South Wales, and it has since proved itself across most warm parts of the country, tolerating heat, poor soil and long dry spells. Full sun, and reasonable drainage; it is not fussy about soil type. Young trees want shelter from hard frost, after which they look after themselves. The failure with this species is almost never cultural, it is siting. Planted a few metres from a house, over a driveway or under a suburban service line, it becomes a problem tree that gets topped, and a topped silky oak throws long weak regrowth on brittle timber that breaks in the next storm. Give it room to reach full size on the day you plant it, well clear of buildings, paving and wires, and do not plant it where the answer in ten years will be a chainsaw at head height. On acreage, plant in a line as a windbreak so the trees shelter each other and grow straighter for it. Established trees are dry tolerant enough for a paddock with no irrigation, and the canopy holds foliage year round, though it thins noticeably in flower.

The upright tree or the low rambler

The two grevilleas here are opposites in every dimension that matters. Forest Rambler is a low spreading plant for banks, wall edges and the front of a bed, flowering through the cooler months and staying close to the ground. Silky oak is a canopy tree that flowers in spring and needs a paddock, a drive or a large native planting. If you want grevillea flowers and honeyeaters in a courtyard or small front garden, take the rambler. If you are planting shade, shelter or a windbreak on land, this is the one, and it is stocked in advanced grades for a head start. There is no middle option here, so do not order silky oak intending to keep it small: pruning will not hold a forest tree at shrub height, and trying produces the weak regrowth described above.

Shaping the leader, and covering your arms

Prune early and lightly to establish one dominant leader, removing competing stems while they are still thin, because a tree allowed to fork low carries a weak union into maturity and that is where storm damage starts. Lift the lower branches over several seasons for clearance, and do not top a mature tree. Wear long sleeves and gloves whenever you prune or handle the sawdust, which irritates skin. Feeding is rarely necessary, and when it is, use a native fertiliser labelled low phosphorus, since the Proteaceae are burnt by the phosphorus in ordinary garden products. Rake fallen leaves and spent flowers off paths, where they are slippery after rain.

Choosing a size

This plant is available in 6 sizes, from 150mm up to 200L, priced from $16.95 to $1209.00 per plant. The size shown is the pot the plant arrives in, which is the rootball, not the height of the plant. The smaller pots hold younger plants that cost less each and establish quickly, which suits hedges, screens and mass planting where the plant count adds up. The larger sizes carry several more years of growth on the farm and give height and presence straight away, which is what you want for a single feature position or a screen that cannot wait. Not sure which to choose? Read our guide to planting for birds.