Most people buy their first bonsai pot by eye, and most people buy it too big.
It is an understandable mistake. A larger pot looks generous. But a bonsai is a tree kept small on purpose, and the pot is one of the instruments doing the keeping. Too much soil holds too much water, roots run instead of ramifying, and the tree slowly loses the compactness you were training it for. Too little soil and it dries out between waterings and stalls.
Here is how growers actually size one.
The two conventions worth knowing
Length: about two-thirds the height of the tree. For an upright tree, measure from soil level to the apex, and take roughly two-thirds of that as the pot's longest dimension. A 9-inch upright tree sits comfortably in a pot around 6 inches long. This is a convention, not a law — it exists because it looks balanced, and because it usually lands close to the right soil volume.
Depth: about the diameter of the trunk. Measure the trunk just above the surface roots. A half-inch trunk wants roughly a half-inch of soil depth for a formal upright. Deeper pots suit cascade and semi-cascade styles, where the tree needs ballast to sit against the weight of a trailing branch.
Where the conventions break: literati styles take a much smaller pot than the ratio suggests. Flowering and fruiting trees usually take a slightly larger one, because they need the water. Cascades ignore the length rule entirely and go tall.
Reading the numbers on a pot listing
Bonsai pots are sold by their longest dimension. A "6 inch oval" is six inches across the long axis, not six inches deep — depth is usually well under two inches on anything in the 4-to-6-inch range. That single detail causes more wrong purchases than anything else.
If you are matching a pot to a tree you already own, measure the root mass, not the tree. The root ball should sit inside the pot with roughly a finger's width of space around it for fresh soil. If the roots are circling the old container, the tree wants root pruning before it wants a bigger home.
What we carry, and why the sizes cluster where they do
Our ceramics run from 4 inches to 10 inches, and the range is not evenly spread — it is weighted to the small end on purpose:
- 4 to 5 inch — shohin and mame, young material, accent plantings. This is our deepest range.
- 5.5 to 6 inch — the workhorse size for a tree in its third or fourth year of training.
- 7 to 8 inch — a developed tree with real trunk movement.
- 10 inch — group plantings and forest arrangements.
Shapes: round for informal upright and broom styles, oval for slanting and forest plantings, square for formal upright and for a firmer, more architectural line, and cascade for anything trailing below the rim.
Prices run $11.99 to $79.99.
Glazed or unglazed
The old convention is unglazed for conifers, glazed for deciduous and flowering trees. The reason is visual, not horticultural: an unglazed pot recedes and lets a pine's bark and needle mass carry the composition, while a glazed pot can pick up the colour of a maple in autumn or a flowering quince in spring.
There is a practical difference too. Unglazed stoneware breathes slightly and dries a little faster, which suits species that resent wet feet. If you are unsure, unglazed is the safer default and the quieter one.
The one thing that matters more than size
Drainage. A bonsai pot needs drainage holes, and enough of them — larger pots should have more than one. Wire holes are a bonus worth having; they let you anchor the tree into the pot so it cannot rock, which is how roots get damaged in the first season after repotting.
A beautiful pot with no drainage is a planter. It will kill a tree slowly and you will not know why.