Silver Banksia Banksia marginata

Silver banksia changes shape across its range, from a low windswept coastal shrub to a small crooked tree with a short trunk, so the form depends on the seed source behind the plant. Leaves are narrow and blunt tipped, dark above with a white underside that flashes in wind, and the flowers are short pale yellow candles that harden into the woody cones people know. It flowers into the cold months, which makes it a nectar source for honeyeaters and wattlebirds when almost nothing else is open.

Cold winters, poor ground and the danger of a watered garden bed

Its range covers South Australia, Victoria, Tasmania and the tablelands of New South Wales, so this is the banksia for gardens that get real frost and cool summers. Full sun, gritty or sandy soil and no attention at all comes close to its ideal, and it copes with exposure, thin soil and drought once the roots are down. What it will not survive is kindness on heavy ground. Planted in an irrigated bed on clay and watered along with everything else through summer, silver banksia rots from the roots up, and Phytophthora dieback moves quickly once it starts, taking a healthy looking plant inside a few weeks. Give it a dry corner of its own, mound the planting position where the soil is heavy, and keep mulch and soil clear of the trunk collar. Frost, wind and thin gravelly ground are ordinary conditions for this species, and it will hold on where most garden shrubs give up. Because mature size varies so much between provenances, measure the space before you commit to a tight position: some forms stay a rounded shrub, others build into a small tree.

Choosing between silver, heath and coast banksia

Silver banksia is the cold climate member of this group. Heath banksia wants a milder coastal garden and gives brighter orange to red spikes on finer foliage, so it is the stronger screening shrub near the water but less at home on a frosty tableland. Coast banksia is a straightforward tree and comes in far larger grades, which matters when you need canopy quickly. Take silver banksia when you are planting for wildlife in a cool inland or southern garden, or when you want a small native tree that will not run away from a suburban block. All three feed birds through the cooler months, so flowering season is not the thing to choose on: let climate, final size and flower colour decide, and buy the coastal species only if the site is genuinely coastal or mild.

Restrained pruning and a light hand with fertiliser

Tip prune from the first season to keep the habit compact, and cut spent flower heads with a short length of stem rather than reaching back into bare wood. A cut branch will not push new shoots from the bare end, though the species carries a lignotuber and can send fresh stems from the base if the top is lost, which is worth knowing before writing off a plant that has been knocked back by frost or stock. Leave some old cones on the plant; they carry the seed and hold the character of the species. Feed with a native fertiliser labelled low phosphorus, or leave it unfed, because general garden and lawn products will burn the fine roots of any banksia. Do not dig or cultivate under the canopy, and keep mulch thin, coarse and off the stem. Water through the first summer, then let it rely on rainfall.

Choosing a size

This plant is available in 6 sizes, from 140mm up to 400mm, priced from $17.95 to $199.00 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 Australian native trees.