Achenbach followed Hans Gude as Professor of Landscape Painting at the Academy. After 1866 he taught one of the highly regarded "Master Classes." Among his best-known students are Gregor von Bochmann, , Themistokles von Eckenbrecher, Arnold Forstmann, Theodor Hagen, Louis Kolitz, Ascan Lutteroth, and Carl Seibels. To his students, he emphasized above all the decisive role of light and dark for the composition of paintings. For him it was more important than the choice of subject. Consequently, he advised his students to familiarize themselves with the paintings of J. M. W. Turner. He also recommended the works of his brother Andreas.
