Hartman was born in Midland and received his BA at McMaster University. From 1976-1981 he lived for periods of time in North Bay, Collins and Heron Bay, working as a landscape painter. In 1981 he settled in the Georgian Bay community of Lafontaine and there became increasingly interested in the historical confrontation of the Jesuits and the Hurons. He began incorporating references to this event into his work, introducing figures and narrative into his paintings for the first time. In 1986 Hartman turned to his personal history, particularly memories of his time spent in the Ojibwa community of Collins, for his subject matter.