Being of a delicate constitution he was shut out from adopting a profession, but devoted himself to the study of plants and the formation of a rich herbarium, which his ample means permitted.
In 1836 he bought the herbarium of Dr. Steudel, and the next year the Prescott collection, consisting of twenty-eight thousand plants.
In 1842 he removed to a more airy house at Lancaster, where he died 21 November 1851 of a sudden attack of an inflammation of the lungs.
Fielding bequeathed the whole of his herbarium, with such of his books as were wanting in the Garden Library, to the University of Oxford.
The figures were drawn by his wife Mary, and the descriptions were written by Dr. George Gardner, who at one time had charge of the Fielding herbarium.