Juniper trees are popular bonsais. Whether growing a native bonsai or a more exotic dwarf Japanese juniper bonsai, proper care is essential for the health and longevity of the tree.
Keeping juniper trees as bonsais has been popular since before the art of Bonsai was brought from China to Japan with the introduction of Chan (Zen) Buddhism in the 12th century A.D. Traditionally, bonsai were kept as potted outdoor trees that were only brought in for display. Japan has a number of juniper varieties that proved to be ideal as bonsai, which meant many kinds of junipers were kept as potted bonsai trees.
Juniper bonsais need water every 3 to 4 days in winter and every 2 to 3 days in summer. Although juniper trees are drought tolerant, they can be more susceptible to spider mites when drought stressed. Trees in very humid areas where the soil moisture does not evaporate as quickly need less water. Trees in dry areas, such as semi-arid or arid climates, need watering more often.
Pruning & Wiring
Juniper bonsais respond well to pruning and wiring. Trees do very well when pruned every few months. Any wire on the tree should be changed every few months to keep the wire from damaging the bark. Trees should be pruned with very sharp scissors or bonsai pruning shears. Bonsai wire should be either aluminum or copper to minimize damage to the tree.
Juniper bonsai are very susceptible to spider mites, especially if the tree is not getting enough water. Spider mites can also be a problem in the winter. The best way to prevent spider mites is to spray the tree every day or two with clean water. This will discourage the mites. Once a tree has been infested, washing the tree every two days under room temperature water will sometimes wash away the mites. If the mites aren't gone after a few weeks, insecticidal soap might be required.
Juniper bonsais need repotting every 1 1/2 to 2 years. The plant should be removed from the pot and the roots should be trimmed back by one-half to one-third, depending on root density. Removing the roots will help maintain the tree's miniature size. Trimming the roots will also solve problems with trees that have become root bound. Plants require air space around their roots for proper health.
Juniper bonsais do best in bright, but indirect, light. In some cases, junipers in direct sun can suffer from green or yellow needles. Although these lighter leaves will not hurt the tree, deep green leaves are generally preferable in a juniper bonsai.
Proper care of a bonsai juniper will result in a tree that will develop a unique character. With good care, some junipers have been known to live for hundreds of years.