Pots are an essential requirement for trees horticulturally and aesthetically.
When choosing a pot, the first consideration must be related to the horticultural needs of the Bonsai because its health should be your top priority. The pot needs holes and feet to avoid waterlog, allow for aeration, and let you anchor the tree when it needs to be re-potted.
Besides the horticultural necessities, the pot artistically plays a great role in enhancing or completing the qualities of your Bonsai. To make things more interesting, you can choose from a multitude of pots in different shapes (oval, rectangular, square, round, hexagonal, octagonal, etc.), size, colour, and glazed or unglazed. Conifers and evergreens are usually displayed in unglazed pots (red, grey, and brown) because the earthy colour highlights the green tint of those magnificent trees. Deciduous Bonsai, on the other hand, are displayed in coloured glazed pots, which balance the tree during the falling period and add some texture and shade. It’s important to avoid a perfect match between the pot and the colours the tree will show when it will bloom to avoid overpowering one or the other element and help the viewer’s eye flow harmoniously.
Another consideration to make when choosing a pot is if the tree looks strong and powerful (masculine) or delicate and elegant (feminine). Deep pots with corners, such as rectangular, square, and hexagonal pots, are usually considered to be a good match for a masculine-looking tree, making it appear well established in the ground, which accentuates the sense of power and stability. Oval and round pots are considered more suitable for feminine-looking trees because they balance the sinuosity and gentleness of them, and the shallowness emphasises the beautiful movement and makes the tree appear taller.
In the end, your Bonsai should please you first, so as long the horticultural needs are met, feel free to make the choices that best suit your taste.