The most common species of the bonsai azalea (rhododendron), the satsuki azalea, originated in Japan. The satsuki azalea produces more than one color flower on the same plant. The pink, white and red flowers grow singly or in pairs. Satsuki means fifth month; the satsuki bonsai tree blossoms in the fifth month each year. Other azalea bonsai plants also produce brightly colored flowers as large as seven inches in diameter. Technically shrubs, the azalea bonsai is trainable to develop into most bonsai styles. Due to the eye-catching blooms, many Japanese bonsai growers refuse to grow anything other than azalea bonsai plants.
Decide where to put your bonsai azalea. Although the azalea bonsai requires sunlight, direct sunlight strips the color out of the flowers and in some cases even kills the flowers. Particularly during the summer, rather than putting you azalea bonsai in direct sun, provide it with filtered sunlight.
Water your azalea bonsai with rainwater if possible. If you do not have rainwater, water your azalea bonsai plant with 1 gallon of water mixed with 1 tbsp. white vinegar once a month. Do not let the soil become dry. Dry roots are fatal to the azalea bonsai plant.
Fertilize the soil twice a month in the spring, until the plant begins to blossom. Stop feeding when the plant has flowers. Once the flowers fade, feed your azalea bonsai monthly. Use slow-acting fertilizer. If you must use chemical fertilizers, dilute them by adding twice as much water as instructed on the package.
Prune your azalea bonsai plant late in the summer, when the plant no longer flowers. Pluck off any dead blossoms and cut back shoots. Reduce clumps of shoots to two shoots each. Do major pruning between early spring and early summer.
Re-pot your azalea bonsai plant in early spring or late winter, as soon as the first leaves appear. Younger trees may require re-potting annually. After a few years, re-pot every two to four years. Before re-potting, trim off all the dead roots and approximately one-third the length of the healthy roots.