It is polymorphic, having early and late season forms of the same plant. Fall culm leaf blades are shorter, narrower, and more crowded than early blades. Winter rosette blades are also short, but are relatively broad.
Vernal panicles are open and produce chasmogamous flowers.
Woolly panicum seeds can be found in the seedbank, but presence of woolly panicum vegetation does not necessarily correspond to presence in the seedbank. Woolly panicum occurs in a wide variety of habitats. Woolly panicum grows on many soil types. Woolly panicum appears in early secondary succession. It does not appear in old-growth forests, but is found in stands of intermediate age.