After attending the Hamburg Gewerbeschule in the evenings, where he was taught by Friedrich Heimerdinger, among others, he studied with the help of scholarships at the Kunstakademie Weimar under Ferdinand Brütt, Karl Gussow and Albert Baur from 1871.
He had close artistic contact with August Wittig [de], who taught sculpture at the Düsseldorf Academy of Arts, and in later years also with the illustrator Heinrich Otto.
Gehrts was also active as an illustrator for books and magazines, for example for the Fliegende Blätter and Die Gartenlaube.
His figures of brownies, gnomes, mermaids and elves, which he developed from legends and fairy tales, were particularly popular.
[6] The Art journal Die Kunst und das schöne Heim [de] characterised him in 1901 as the "last romantic among German illustrators".