Cottony Fireweed is an herbaceous annual or weak perennial herb branching from near the base. It is a strong primary colonising species that frequently springs up following fire. It is quite distinctive amongst the group of locally-native Fireweeds for its open form and long bluish-green foliage; especially in its early stages of growth. As it matures the leaves become progressively smaller towards the apex of each stem which then culminate in clusters of loosely arranged flower heads.
Leaves and stem are covered in whitish hairs with the underside of leaves woolly.
Flowering occurs over a long period from September to early autumn. Flowering is particularly responsive to rain episodes however the flowers are relatively nondescript with many tiny florets enclosed within discoid flower heads. These quickly form seed which are adapted to be carried relatively long distances by wind.