Bonsai plants can be propagated in water by taking cuttings from the growing tips of a young tree. Cuttings are taken using a sharp knife and a clean glass, or plastic container. The water used to grow the cutting should be changed every few days, and it is important that the water is clear. Bonsai cuttings need lots of light when they are first planted in order to produce roots. A bright window sill or garden shed is ideal for growing cuttings in, but they can also be grown under artificial lights.