Ehret was the dominant influence in botanical art during the mid-18th century, and his work is highly prized today for both its botanical accuracy and aesthetic appeal. Wilfred Blunt comments: 'Ehret's greatest merit is that he succeeded as few other botanical artist have succeeded; in being at once both botanist and artist' (S. Sitwell and W. Blunt, Great Flower Books, London, 1956, p. 331).
Ehret was taught by his father, a gardener in Heidelberg. He began his career as a gardener to the Margrave of Baden Durlach, Karlsruhe, and while there assisted the botanical watercolourist August Wilhelm Sivert (fl. 1720-1760) in preparing his paints. This inspired him to execute his own plant portraits which he presented to his employer.
He departed for Nuremberg in 1733, where he met Dr Christoph Jakob Trew (1695-1769), who was to become his life-long friend and patron. Between 1734 and 1735 Ehret visited Paris, where he must have had access to the Vélins du Roi. So impressed was he by the superior qualities of vellum over paper, that he henceforth adopted watercolour and later bodycolour on vellum as his preferred medium. Ehret settled in England in 1736, remaining there for the rest of his life as a botanical artist and drawing master. His reputation was extended by the publication of various flower books based on his drawings, including Dr Trew's Plantae selectae, 1750-1773 and Hortus Nitidissimus, 1750-1786. Gerta Calmann maintains, however, that his original drawings 'were the true expression of his genius' (Ehret Flower Painter Extraordinary, Oxford, 1977, p. 99).