Greenleaf is a city in Canyon County, Idaho, United States. The population was 846 at the 2010 census. Greenleaf is part of the Boise-Nampa m…Greenleaf is a city in Canyon County, Idaho, United States. The population was 846 at the 2010 census. Greenleaf is part of the Boise-Nampa metropolitan area. The town was established by Quakers in the early-1900s and is named after Quaker poet and abolitionist John Greenleaf Whittier.