Identify the growth patterns of the bonsai, since not all bonsai trees go dormant during the winter months. Watch for the slowing of growth, as this will signify the tree's dormancy periods.
Exercise patience during the growing season and allow your bonsai to grow freely. Prune your bonsai during the growing season only when necessary to maintain its health.
Pinch away with your thumb and forefinger dead, dying or damaged foliage, and stems or branches as they appear. Trim away the damaged or dying twigs and branches, using sharp, sterile pruning shears. Make flush cuts and sterilize the pruning shears between each cut.
Hard prune your bonsai once a year during the tree's dormancy period. Remove unwanted branches and stems that go against the desired shape, using sharp, sterile pruning shears. Remove dead, dying and damaged wood and foliage, as well. Complete the bonsai's training gradually, over the course of several growing seasons, to prevent dieback and to maintain a healthy tree.
Water your bonsai thoroughly with tepid water immediately after each pruning. Irrigate the bonsai until the water flows evenly from its drainage system. Place the bonsai in a warm, sunny location to allow it to heal.
Prune the bonsai's root system about once every two years. Complete the process in the early spring, just before the growing season begins. Remove the bonsai from its container and place it on a clean surface.
Remove about one-third of the root mass, using a sterile root hook, as explained by Bonsai For Beginners. Remove the excess soil gently from the root system and thoroughly inspect the roots.
Look for dead or damaged roots that usually appear wilted and discolored. Trim away the damaged roots, using sharp, sterile pruning shears or scissors. Trim no more than one-third of the root system to prevent dieback and growth stunt of the bonsai.
Line the bottom one-third of the container with a layer of soil. Position the bonsai in the center of the container. Fill the container with soil while making sure that all of the roots are covered. Press the soil firmly around the bonsai to secure its upright position. Irrigate the newly pruned and repotted bonsai thoroughly to promote a good establishment.
Wire the branches of the bonsai to develop your desired shape. Select aluminum wire in several different thicknesses to accommodate the varying sizes of your bonsai's branches.
Complete the wiring process in the early spring during the onset of the growing season. Start the wiring from the trunk and work your way outward to the end of the branch. Apply the wire at a 45-degree angle. Allow the wire to remain in place until the wired branch grows into the new position. Watch your bonsai carefully, as this process can take as little as two weeks or up to one year. Trim the wire from the bonsai, using metal cutters.