—painted by Thomas Heaphy (1816)
Having decided to become a painter of flowers his first venture was with William Curtis, whose Flora Londinensis he illustrated. Sowerby studied art at the Royal Academy and took an apprenticeship with Richard Wright.
An early commission for Sowerby was to lead to his prominence in the field when the botanist, L'Hértier de Brutelle invited Sowerby to provide the plates for his monograph, Geranologia, and two later works. He also came to the notice of William Curtis, who was undertaking a new type of publication. Early volumes of the first British botany journal, The Botanical Magazine, contained seventy of his works.
In 1790, he began the first of several huge projects: a 36-volume work on the botany of England that was published over the next 24 years, contained 2592 hand-coloured engravings and became known as Sowerby's English Botany. An enormous number of plants were to receive their formal publication, but the authority for these came from the unattributed text written by James Edward Smith.