Bonsai are living, growing pieces of art. Contrary to popular belief, bonsai are not their own species of tree, but are natural trees cultivated to grow at a small scale. While the word “bonsai” conjures images of gnarled trunks and tiny pink blossoms, it is possible to grow bonsai versions of anything from redwoods to willows. Each type requires slightly customized care, including a specialized bonsai tree fertilizer.