James Barnes was baptised in 1806. He was the eldest son of a head gardener and began work (mainly weeding and bird scaring) at the age of five. His apprenticeship began under his father in 1814, and was continued in London from 1818. He went on to work in market gardening, and was especially skilled at forcing cucumbers and breeding new varieties.He went on to developing pleasure grounds at Beulah Spa, then became head gardener at Cranford House in Essex.
In 1839 he began work at Bicton in Devon, where he stayed for nearly 30 years. He was extremely well-respected for his great horticultural skill and his orderly approach, and the garden he developed at Bicton was much-admired by John Claudius Loudon amongst others. He eventually left his post under acrimonious circumstances, successfully suing his former employer for libellous claims that he had left the gardens in a poor state. He died in Devon in 1877.