Stock Photo - Cotoneaster Evergreen Flowering Bonsai Tree. Cotoneaster microphyllus is a fully frost hardy evergreen variety with tiny little leaves. In spring the tree is absolutely covered in small white flowers that are followed in autumn by small deep red berries. Cotoneaster is one of the easiest species to care for and is well suited to those with limited bonsai experience. The tree is fully hardy over winter and will stand very low temperatures. In summer it can grow anywhere from full shade to full sun. It appreciates watering well in summer. Repotting should be infrequent, growth and flowering performance is much improved if these trees are kept a little pot bound.