The Montreal Botanical Garden is the second largest botanical garden in the world. Its gardens feature more than 26,000 types of plants, ranging from general gardens to theme gardens. You'll find authentic Chinese and Japanese gardens among the various gardens on the grounds. Also on the grounds is an Insectarium. You can easily spend a couple hours to all day at the garden.

Mark Wasson, http://www.markwasson.com > Trips has detailed summaries of my trips