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Horticulture Questions and Answers

How do I care for a bonsai plant?

Bonsai plants have become very popular to purchase for oneself or to give as gifts. Unfortunately many die due to improper care.

Primary to determining how to care for your bonsai plant is to first determine whether your plant is a tropical or subtropical indoor plant or a hardy, outdoor one. Plants, such as, maples, pines, junipers and boxwoods are outdoor hardy plants and their care differs from indoor tropical plants such as weeping fig, dwarf pomegranate, natal plum, rosemary and Serissa. Indoor plants are best grown indoors as house plants but may be set out of doors for the summer as you would other indoor plants. Hardy, outdoor plants on the other hand, require outdoor growing conditions for best growth. They should be brought indoors for only short periods of time for display and then returned to their outdoor growing area. Trying to grow a hardy, outdoor bonsai plant indoors will most likely result in failure unless you are able to replicate outdoor conditions.

Whether you are growing indoor or outdoor plants, proper light is very important. Most outdoor plants require good light. Full morning sun and some afternoon shade is ideal for most plants but pines and junipers can tolerate full sun all day. Indoor bonsai plants should also receive good light. Most will require a south or east facing window. A good indoor plant book can provide you with light requirements for various indoor plants.

Proper watering is very important. Since bonsai pots are small and dry out quickly, plants need frequent and careful watering. In spring, summer and fall this often requires at least daily watering. On hot days, two waterings may be required. Think of your bonsai plants as a pet! They can't bark when they're thirsty but if you let them go a day without watering in the summer, you may have a crisp, dead plant. Use a fine mist when watering so as not to wash the soil out of the pot. Water until drainage runs through the holes in the bottom of the pot. If water runs out of the pot as soon as you water the plant, the soil may be too dry and shrunk away from the pot. If this occurs, soak the pot at once to rehydrate the soil.

Even though bonsai plants are meant to be small, proper fertilization is still necessary. The plant needs to continue to produce new leaves and roots to stay alive. During the growing season, a water soluble fertilizer such as 20-20-20 can be used, or, for greater convenience, use a time-released fertilizer. One application of a time released fertilizer applied in early spring will generally last the full growing season.

Regular trimming and pruning is required to keep the plants small. Remove much of the vigorous new growth in the spring as well as periodically throughout the growing season, but be sure and leave enough leaves to maintain the vigor of the plant. Pruning and training is an art form and will require much study and practice before it is mastered. Many books are available on the subject and should be consulted for more complete details.

Repotting needs to be done periodically. Most deciduous plants should be repotted every two or three years. Pines and junipers grow more slowly and require repotting every four or five years. When repotting, remove the heavy old roots but retain as many of the fine feeder roots as you can. Be sure to use a well-drained soil mixed with screened sand and repot in early spring just before the plants begin to make active growth.

Winter care of indoor bonsai does not differ from winter care of other indoor plants, namely, cut back on watering and fertilizing when the plant's growth slows. For winter care of hardy outdoor plants see "How do I overwinter my bonsai plant?"