Protea afra grows as a shrub or small tree with a somewhat rounded crown and is common in the natural areas of the botanical garden. The grey-green leaves are elongated with nearly parallel sides. They are leathery in texture and may be up to 250mm in length.

 The flower heads (which may be mistaken for individual flowers) can be borne singly or in clusters. They reach up to 80 mm in diameter with the outer bracts (resembling petals) varying from reddish to pink or cream in colour. Many tiny, single flowers are clustered together in the flower head. When pollinated each flower forms a small nut which is covered in rich reddish brown hairs.

The thick bark has a chunky, corky texture. It protects the mature plant from the fires that are essential to the maintenance of the grasslands in which the common sugar bushes grow. Caterpillars of Capys penningtoni (Pennington's protea) and Capys disjunctus butterflies feed on the flowerbuds.