Propagation
Fresh seed should be sown in a well-drained media and the kept moist but not wet. Maintain a temperature of 18º to 21º C. (64º to 75º F) in an unheated glasshouse or open frame.
Germination occurs within 3-weeks to 3-months depending on the species, then prick out and pot up. Careful not to over water seedlings, as they are prone to damping off and larger plants are difficult to transplant.
When removing seed from Banksia fruits it may be necessary to place the fruit in an oven for 60 minutes at a temperature of 120° C. to simulating the effect of a bushfire to opening the valves.
Botanic information
Leaf: The grey green long linear leaves are up to 40mm (1½in) with a truncate apex and the margins consist of triangular pointed lobes. The upper surface is tomentose at first turning glabrous and the underside is covered in white tomentose.
Flower: The small tubulate flowers are pale yellow with the pistil up to 55mm (2?in) long and arranged in a terminal spike that is up to 120mm (4µin) long and 100mm (4in) wide. The flowers are bird pollinated and persist on the plant when old. They appear from early summer to autumn.
Fruit: The woody elliptical follicle is up to 30mm (1?in) tall and wide and is densely velvety. There are up to 20 follicles arranged in the cylindrical fruit and the obovate seed to 45mm (1µin) long and 12mm (½in) wide has a large curved notched wing.
General pruning information
When pruning reduce only the new growth as cutting old wood is likely to cause dieback. Limbs may be removed back to the collar.
Cultivation
Generally, Banksia species prefer a well drained, sandy soil that is tending acidic but many species from Western Australia grow on acidic top soils with an alkaline subsoil.
When growing Western Australian species outside their native habitat technique of building a garden bed, of acidic soil above a layer of agricultural lime commonly produces better results particularly in raised garden beds or on slopes.
During establishment, keep the soil moist but not wet and do not use fertiliser that contains phosphorus.