The youngest of all the sons of Joachim Ernest who survived to adulthood, he grew up in Dessau at the court of his older brother and guardian, John George I.
During a stay in Florence, Louis was accepted (with the assistance of his Italian tutor Bastiano de' Rossi) as the first German member of the Accademia della Crusca, in which he was known by the name "L'Acceso."
Problems with the local clergy led to Ratke's imprisonment for eight months, and Louis left this project incomplete.
On the occasion of the funeral of his sister Dorothea Maria, Duchess of Saxe-Weimar, on 24 August 1617, the seneschal Kaspar von Teutleben proposed the establishment of a society on the model of the Accademia della Crusca.
During the Thirty Years' War, King Gustavus Adolphus of Sweden transferred the governorship of the Dioceses of Magdeburg and Halberstadt to Louis.