Beginner's Page: What Are Bonsai?

by Brent Walston

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The simplest definition for bonsai is a plant in a pot. But bonsai is so much more than a tree treated like a house plant. It is plant art, or sculpture to be more accurate. Bonsai require skilled care to survive and to blossom into magnificent specimen plants.
Many nurseries and vendors sell inexpensive plants in pots and call them bonsai. With care they could become bonsai, but they are not bonsai. On the internet we have the adopted the term 'Mall Bonsai' or 'mallsai' for these plants. Some of these people are true bonsai folk and do their best to see that your plant survives by giving you at least basic care instructions. Sadly, other vendors could care less. We recommend that you do not purchase bonsai from persons unwilling or unable to give you care information.
Bonsai are not houseplants. For the most part they are outdoor plants and must remain outdoors all year long. This is because most bonsai are temperate climate plants that require a period of dormancy. This is true for evergreens such as juniper as well. There are also indoor bonsai, but these are usually limited to tropical and subtropical species, and even these species are happier outside in the summer. Since the roots of outdoor bonsai are exposed, they must be carefully over wintered in cold climates to prevent the roots from reaching killing temperatures.
Little bonsai do not become big bonsai. They are grown under training conditions until they reach the desired size and trunk thickness and are only then transferred to bonsai pots. Plants grow very slowly once they are in bonsai pots, that is the object of the pot, to slow down growth to reduce leaf and twig size. Most of the inexpensive (and some not so inexpensive) mall bonsai have had little or no training whatsoever. This is why we do not consider them to be bonsai. Trees must becarefully trained to achieve the beautiful shapes most people associate with bonsai.
The training of bonsai is done mostly by manipulating the trunks and branches through pruning and wiring. Anyone can learn how to do this with a few hours of basic instruction from a teacher or by reading books. Of course, advanced skills are honed over a period of a lifetime, and the more your practice, the more you will learn.
Bonsai must be root pruned and repotted occasionally. Since the object is to keep the tree the same size, they usually go back into the same pot after root pruning. Root pruning is also a training technique and a plant may be invigorated or slowed down by timely pruning. The trees are repotted with fresh special soil designed specifically for bonsai. The most important quality of bonsai soil is that it drains very much faster than usual potting soils.
Bonsai must be fertilized regularly while actively growing. This is most easily achieved by fertilizing with a good soluble fertilizer every two weeks. Use a fertilizer with trace elements such as Miracid or Miracle Grow at the full strength recommendation. Bonsai soils are not very good at holding nutrients, so regular full strength feeding is a must.
Watering improperly is probably the most common problem for beginners. Plants must be watered thoroughly when they become slightly dry. Watering should be done from the top, not by submerging the plant, and they should be watered until they are saturated. You will see water pour from the drain holes when they receive enough. This method of watering helps to prevent salt buildup in the soil.
Determining when a plant is slightly dry can be tricky. We recommend that you lift the pot (if it is a small bonsai). There is a substantial difference in weight between a well watered bonsai and one that needs water now. You will learn this 'feel' very quickly. You can also dig your finger down about an inch into the soil. If it is dry to this level, it should be watered. Another method, recommended by Michael Persiano, is to insert a chopstick into the soil as sort of a dipstick. Leave this stick in the soil and pull it out periodically to test the water 'level'. If the soil has adequate water the stick will be damp.
Most people in hot summer areas find that watering is necessary every day when the temperature is above 80F. Sometimes, watering is necessary twice a day. In general, indoor plants require less frequent watering than outdoor plants.