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.
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.
Botanic information
Leaf: The pale to mid green narrow linear leaves up to 28 mm (1? in) long by 1 mm wide with strongly revolute margins and an acute apex. The upper surface is pubescent at first and the hidden underside is woolly.
Flower: The cream to pale yellow tubulate flowers have straight glaborous perianth segments that are up to 35 mm (1? in) long and a glabrous pistil to 45 mm (1µ in)long. They are arranged in a cylindrical-ovoid spike that is 30 mm to 60 mm (2? in) long by 90 mm (3½ in) wide with basal bracts that are covered in tomentum. They appear terminally or axillary on short lateral branchlets from spring to early summer.
Note:
Generally Banksia flower spikes are composed of hundreds of small individual tubular flowers (florets) that are densely arranged around a single cylindrical axis.
Fruit: There are up to 80-embedded smooth narrow elliptical follicles that are up to 28 mm (1? in) long by 9 mm (? in)high and 8 mm (¥ in) wide arranged in a villous spike that is persistent of the plant. The follicles open after fire and release broadly obovate seeds with a body up to 15 mm (? in) long by 5 mm (? in) wide and have a wing that is up to 25 mm (1 in) wide.
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 alkaline subsoil.
When the 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.