how lond did lawren harris create artwork?

Answer 1

"Lawren Harris was born on October 23, 1885, in Brantford, Ontario, to a wealthy family - The Harrises of the Massey-Harris industrial fortune.

He took up painting at an early age and studied in Germany from 1904 to 1907. He worked briefly with Norman Duncan, illustrating several of Duncan's stories, but Harris was in fact the only member of the Group of Seven who was free all his life from monetary pressures and temptations of commercial art and advertising designs.

Harris is also the only member of the Group who kept pushing his painting, never resting for long with one style or one species of subject matter. Long after the Group disbanded, Harris continued to grow and change as a painter, moving eventually into art deco and pure abstraction ...."

http://www.groupofsevenart.com/artist_biographies.html
http://www.tomthomson.org/groupseven/harris.html

He died in 1970, (making him 85 at his death) so that would give him a good 70 or more years of painting experience.