Banksia violacea is rarely cultivated . It is a slow @-@ growing plant that tend to become untidy with age , and generally do not flower until four to five years after sprouting from seed . Flowers are an unusual colour , but occur within the bush where they grow within and are usually obscured by foliage . It tolerate light pruning not below the green foliage , except for the variant with a lignotuber , which may be pruned heavily . George recommend a sunny position in light , sandy soil . Professor Margaret Bernard Sedgley of the Waite Institute suggest the species is of no value to floriculture , as the inflorescences are too small and obscured by the foliage , although she do add that the purple colour may be a worthwhile character to select for in plant breeding . Seeds do not require any treatment , and take 19 to 50 days to germinate .