The flora and fauna on the hill have been recognised to be of particular importance, and is such that the hill was designated as a biological Site of Special Scientific Interest in 1978. Ladle Hill typifies a calcareous grassland chalk downland habitat now scarce in Britain, and is home to some unusual and rare species. The earthwork in particular is very rich in species, with a good range of downland grasses and large populations of rare and local plants such as field fleawort, Senecio integrifolius; chalk milkwort, Polygala calcarea; hairy rock-cress, Arabis hirsuta; fragrant orchid, Gymnadenia conopsea; and pyramidal orchid, Anacamptis pyramidalis. The earthwork escarpment slopes, though species-rich, support fewer species than within the fort, but some, notably clustered bellflower, Campanula glomerata, only occur there.