The bonsai is our main display, but thepot is our main means of displaying it, so the choice of a pot is a crucial one to our bonsaiâ€™s appearance. I have yet to buy a commercial grade tree (I canâ€™t afford the artist grade trees) that I didnâ€™t think needed transplanting. Usually it was the soil mix (beware of glued down rocks), but as often as not I was in a hurry to get it out of the ugly container it was in and into something more appropriate (Iâ€™ve had dates just like that, tooâ€¦).
The ideal proportions for the pot are as follows. It should be 2/3 to 3/4 as wide as the tree is high and 1/2 as deep as the tree is high. The height of the pot should be roughly the same as the diameter of the trunk; while first establishing trees this last rule should relax a little. The dimensions given are for showing trees; when Iâ€™m first styling and changing the structure of the tree I donâ€™t think about repotting and there are more than a few trees I still have in nursery containers despite the fact that I have had them for five or more years!
Bonsai Pot color considerations
Colors are our first concern with pot choice. Muted earth tones work best with most plants, although flowering varieties can be accented nicely with a glazed pot in an appropriate tone (Many of the pots I see today are in colors more appropriate to a Matisse painting than bonsai pots; avoid these at all costs). Glazes work better with tropicals; they are usually as hurt by freezing as the tree in them and so many of the tropicals flower as well, making colored pots less obtrusive.
Unglazed pots are more rustic and earthy and the dark brown and reddish tones of earthenware are perfect foils for green foliage; while I own many glazed pots they are all sitting on the shelf sans trees. ALL my trees including my three foot tall tropical ficus are in either Japanese brown mud pots or Chinese red clay. But pots like trees are a matter of personal taste, so find a pot that suits your tree and your taste.