Young plant growing from rhizome. Fireweed requires light to germinate and therefore can only establish itself on bare ground, often after a fire, giving it its name Fireweed, but also in new conifer woodland clearings where no other plants and coarse debris shades the seed. Once established this perennial plant will grow new shoots every year from the creeping rhizomes which can spread the plant outward. It often grows in dense patches.

Flower spike with flowers developing progressively towards the top.