Banksias

Choosing the right banksia

Pick by mature size first. For groundcover, 'Roller Coaster' hugs the soil at about 30cm high while spreading past 2m, and 'Coastal Cushion' makes a dense mound to 50cm. The compact Banksia spinulosa cultivars, Cherry Candles, Honey Pots, Stumpy Gold and 'Little Pal', sit around 1m and carry full sized flower spikes on small plants. In the middle, Lantern Banksia and 'Giant Candles' build 3m to 4m shrubs with spikes up to 30cm long. At tree scale, the Coast Banksia (Banksia integrifolia) reaches 8m to 15m, and Silver Banksia suits cooler southern gardens.

Where banksias grow well

Most banksias evolved on sand, so free drainage is the one non negotiable. Coast and Wallum Banksia take front line salt wind from Queensland to Victoria. The spinulosa cultivars handle frost and heavier soil better than most of the genus, Silver Banksia is the pick for the cold south, and Swamp Banksia is the exception that tolerates damp ground.

Planting, feeding and care

In clay, plant into a mound or raised bed 300mm high rather than a hole that holds water. Water deeply once a week through the first summer, then leave established plants to the rain. Feed once in spring with a low phosphorus native fertiliser only: banksias are phosphorus sensitive, and a standard complete fertiliser can kill them. Mulch 50mm to 75mm, and tip prune lightly after flowering to keep compact forms dense.

Common questions

Why did my banksia die after I fertilised it?

Almost always phosphorus toxicity. Standard garden fertilisers carry more phosphorus than banksias can process. Use a native formulation with a P figure under 2 percent, once a year at most.

Which banksia suits a pot?

Honey Pots, Stumpy Gold and 'Little Pal' all flower well for years in a 40cm to 50cm pot of native potting mix, watered deeply whenever the top few centimetres dry out.

When do banksias flower?

Mostly autumn through winter, with some spinulosa forms running into spring: nectar for honeyeaters in the garden's quietest months. Banksias pair naturally with the rest of our Australian native plants.

Will banksias grow in clay soil?

Swamp Banksia will take it as it comes. For everything else, mound the bed 300mm and let drainage do the rest, or grow a compact form in a pot. For more shrubs this unfussy, see the low maintenance shrub collection.