Blanket bogs are characterised by plants that thrive on waterlogged, acid peats such as bogmosses, cottongrasses and deer sedge. They occur on deep peats on the moorland plateau, generally at altitudes of at least 400 metres. In addition to high quality blanket bog of the type described above, this Plan also includes degraded blanket bog which has become dominated by purple moor-grass, but which still retains some blanket bog species.
Because blanket bog requires very wet conditions, it is concentrated in the south-western part of the National Park, where the prevailing winds result in the highest rainfall levels.