Although modern techniques enable disused colliery waste heaps to be reclaimed for agricultural and recreational uses, the cost of establishing the necessary soil cover severely limits the number of schemes simultaneously under way. Natural colonization of waste heaps is characterized by the importance of a relatively small number of species. Examination of the relationship between these species and the immediate environment of the waste heaps suggests that the unstable surface material and loss of fine silt by erosion are the significant factors. Such species could be used to help establish a soil cover in reclamation projects.