 He was the son of Johann Andreas Grabau and Anna Dorothea Jericho.Grabau was educated at the grammar school in Olvenstedt (1809–1818), the Magdeburg Gymnasium (1818–1825) and at the University of Halle (1825–1829).After three years as a teacher in Magdeburg and Sachsa bei Nordhausen, Grabau was ordained and installed as pastor of St. Andrew's Church in Erfurt in June 1834.