Banksia ashbyi is a shrub or small tree that typically grows to a height of 8 m (26 ft) and sometimes forms a lignotuber. It has smooth, grey bark and young stems that are hairy at first but become glabrous as they age. The leaves are broadly linear, 100–300 mm (3.9–11.8 in) long and 20–40 mm (0.79–1.57 in) wide and deeply serrated, the serrations triangular with sharply pointed tips. The flower spikes are bright orange, 60–150 mm (2.4–5.9 in) long and 60–80 mm (2.4–3.1 in) in diameter, each perianth 26–34 mm (1.0–1.3 in) long. Flowering occurs from February to May or July to December and the fruits are numerous smooth, elliptical to round follicles 8–15 mm (0.31–0.59 in) long, 3–8 mm (0.12–0.31 in) high and 5–11 mm (0.20–0.43 in) wide with a covering of short, soft hairs
Banksia ashbyi has the northernmost distribution of any Western Australian banksia. In the northern part of its range (Shark Bay north to Exmouth), it is a lignotuberous shrub to 2 m tall (i.e. it has a lignotuber and is therefore fire-tolerant). In its southern range (Shark Bay south to Moora), it is a non-lignotuberous (and therefore not fire-tolerant) shrub or small tree to 8 m tall.
Ashby’s banksia produces large bright orange flowers from February to December making it an excellent plant for attracting nectar-feeding birds into your garden, and a great banksia for cut flowers.Grows best in a dry summer climate, and requires well-drained, preferably sandy soils and full sun to light shade.
It prefers organic mulch, is very sensitive to phosphates, but responds well to light application of slow-release, low-phosphate fertilisers specifically designed for Australian native plants.
Banksias respond well to light pruning after flowering.