Don's main work was his four volume A General System of Gardening and Botany, published between 1832 and 1838 (often referred to as Gen. Hist., an abbreviation of the alternative title: A General History of the Dichlamydeous Plants). He revised the first supplement to Loudon's Encyclopaedia of Plants, and provided a Linnean arrangement to Loudon's Hortus Britannicus. He also wrote a monograph on the genus Allium and a review of Combretum. He died at Kensington, London, on 25 February 1856.