Defoliation of a bonsai tree is the technique of removing some or all of the leaves from the tree during the summer season. This can help to reduce the size of the new leaves, increase the branching, and improve the health of the tree. However, defoliation should only be done to healthy and mature trees that can tolerate this stress. Defoliation is usually done in late spring or early summer, after the new growth has hardened off. The leaves are cut with scissors or a leaf cutter, leaving the leaf stalks intact. The tree should be watered well before and after defoliation, and not fertilized until new leaves appear. Defoliation can be done to most deciduous trees, but some species may not respond well to this technique.