Choosing a Bonsai Pot:Think of a pot as similar to a frame around a picture.
We have chosen a plant that we think has the potential to eventually become a bonsai with 'character'. There are now a few things we need to have available so that this plant can indeed become a bonsai. We will, of course, be discussing bonsai style, pruning, etc., but a brief look at bonsai pots will enable us to visualize our plant in a suitable pot while we are working on it.
A good bonsai is in proportion. The trunk, branches and leaves or needles must be in balance. The pot not only gives the roots a place to be, and holds soil that retains moisture and nutrients, it enhances the appearance of the plant without obvious. Think of a pot as similar to a frame around a picture. It defines the picture, makes it look complete and often adds to the attractiveness of the picture. If you notice the frame before you appreciate the picture, it is the wrong frame. A bonsai pot should not be so shiny, brightly coloured, decorated or out of proportion that it is the first thing that we see. It should, rather, add balance to the base of the plant to complete the overall appearance. There is much variation in size, colour, shape and glazing in bonsai pots.
Bonsai that grow upright are usually grown in shallow oval or rectangular pots, while those that grow downward are grown in taller, narrower pots. There are many variations of these basic shapes - rounded corners, flared tops, small feet, for example. A tree that has a strong trunk and heavy branches will look balanced in a thicker-walled, heavy container, while finely leafed plant will need a more delicate pot to look its best. Colour must also be appropriate. Evergreen trees look best in unglazed pots, as a rule, in varying shades of brown, cream or red clay. Flowering plants are often placed in glazed pots, in colours complimenting or blending subtly with the flower colour. A tree with dark coloured leaves would look best in a dark pot, as a light one would immediately draw attention to the pot rather than to the plant. Often a secondary colour in the plant is picked up in the pot colour, such as the reddish stems in an Amur maple suggesting a red clay pot, or the cream blotches of a variegated weeping fig enhanced by a cream pot.
The width of the pot for an upright tree should be about two-thirds the height of the tree, or the height of the tallest tree in a forest. The depth of the pot is about the diameter of the trunk near the base. For a cascade style, the pot must be deep enough to create a sense of balance in the tree, allow the downward-growing branch to hang freely and be narrow enough to allow the branches to cascade down over the sides of the pot. As we suggested in choosing and styling a plant, the choice of a pot is yours, and should be pleasing to you. There a very few absolutes in bonsai, and much scope to create your own special tree. One absolute, however, is that every bonsai pot must have at least one good-sized drainage hole. To prevent soil from escaping, cover the hole with a square of fibreglass screening a little larger than the hole.
The subject of soil is decidedly controversial! To make a beginner feel a little more confident, consider what type of plant you are working with. A tropical houseplant will be reasonably happy in a soil similar to that in which it was growing before you made it smaller. Usually this would be a mixture of peat moss, sharp sand and vermiculite and/or perlite. This is called a soil less mix, as it contains no soil or loam. It is light and it drains quickly so there is ample oxygen around the roots. It contains no natural nutrients, so a suitable fertilizer must be used regularly. Earthworm castings either purchased or the result of indoor composting, add body and nutrients to soil less mixes and are highly recommended.
Outdoor deciduous trees require a similar mixture, with possible fine granite replacing the sand, depending on the size of the pot. Often, very fine bark, such as that used for orchids, is added to evergreen mixes. Loam from outdoors should not be brought into the home for tropical plants. If trees are routinely placed outdoors for a part of the year, good quality loam, screened to remove unwanted weed roots and seeds, insects, etc., an be used as part of the mixture. If they are brought into an area where houseplants are also grown, great care should be taken to avoid possible insect pests from spreading to other plants. All bonsai soil should be screened or sifted to remove the finest particles, so that what is used is coarse enough to allow good drainage and ample air space around the roots.
This is greatly over-simplified for experienced bonsai growers, but we want our newest recruits to feel confident that they can enjoy this wonderful hobby! There is ample time to learn all the variations possible, once they have tried their first bonsai and found out how rewarding it is. Many people, and books, suggest several layers of planting material with the bottom layer of coarse material, an intermediate layer and a top layer of finer material. This is more appropriate for larger bonsai, which most beginners won't be attempting at first. When we are confining the roots of a plant to a relatively small pot, the rots can soon reach a layer of coarse grit, granite etc. which holds very little moisture and nutrients. As long as the drainage hole is clear and excess moisture can drain away easily, there should be no problem with using the same mix for the total depth.
Now we have a plant, a pot and some soil - a good beginning! Have fun!