BANKSIA baxteri

Although seed can be sown most of the year in Australia seed is generally best sown in spring or autumn in temperate climates, avoid the coldest and hottest months of the year. The optimum germination temperature for germination is around 18-22°C

1. The growing medium should be well draining but should remain damp between watering.
2. Sow the seed the depth on the seed size. Vermiculite is a good medium to use to cover the surface as it helps retain moisture and controls the temperature. 
3. Keep moist but not too wet as the seed may rot. Do not let the growing mix completely dry out. 
4. Germination should occur in 21-60 days depending on the temperature and conditions. 

Pre-treatment of smoke: Not considered critical to germination of this species and germination will generally occur without it.
However many members of the Proteaceae family are responsive to pre-treatment of smoke. Although germination will often occur without smoke treatment it has proved to be beneficial in reducing the number of days to germination and increasing germination rates in many species of the Proteaceae family.
Smoke treatments are simple and can be undertaken either by soaking the seed overnight or by applying to the surface after sowing, both provide good results. Smoke treatments available by clicking here.

General note: Seeds of many natives are dormant and require specific conditions or pre-treatment for germination.
Do not be too hasty to discard seed that does not germinate, seeds will often lay dormant until the conditions are similar to their natural requirements for germination to occur. Containers put to one side will often surprise long after they were discarded.

Florabase of Western Australia

Australian Native Plants Society (Propagation of Banksia)

Wikipedia