Banksia: Greenhouse Plants
C – cool, minimum of 7°C (45°F)
These handsome plants can be very difficult to grow and flower unless a few basic but vital points about them are understood. They need very good light and ventilation. They also hate phosphates in theiror feed and are not at all that keen on nitrogen-rich feeds either. Fortunately Chempak make a fertiliser that is phosphate free which can be used. They require a very free-draining compost of equal parts of peat and grit without any added fertiliser. They are very prone to dampness in the air and overwatering at the roots, particularly in winter. However, if you can solve all their growing problems they are fine distinctive plants to grow. The magnificent flower spikes can each contain more than 1000 individual flowers. Leaves are generally long, thin, toothed and downy beneath. Seed should be surface sown at 18-21°C (65-70°F).
Banksia coccinea has long leaves with small teeth along the edge and bright red flowers in spring looking like bottle brushes gone mad. B. robur from New South Wales has good foliage with velvety undersides. Flowers are yellowish-green in huge spikes.