The Janet Cosh Herbarium at the University of Wollongong was established by a bequest in her will. It houses her specimens, illustrations and other materials including field notebooks, photographs and maps.[4] The position of curator of her eponymous herbarium was funded by her bequest until it was exhausted in 2020, but the herbarium itself is supported by the university.[5]
Another bequest enabled the creation of the Janet Cosh Memorial Room at the visitors centre at Fitzroy Falls through the Foundation for National Parks and Wildlife. The room holds specimens of local flora and copies of some of Cosh's botanical illustrations.[4]