A pot for this tree
Broadleaf evergreen (ficus), formal upright (chokkan), over 70 cm tall, trunk slim (under 2 cm).
Rules of thumb, as bonsai people have passed them on; a good eye beats a tape. Measure the tree's height from the soil to the apex and the trunk just above the surface roots.
Where to look
A rectangular glazed pot, about 50 cm
The recommendation itself, as shops list it: sizes are rounded to the ones sold, so look at 50 cm and the size either side.
Search: bonsai pot rectangular glazed green 50cm
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See also
Glazed ceramic pot (oval)
What to look for: Frost-proof stoneware with a glaze that complements leaves or flowers: blue, green, cream or oatmeal. For deciduous and flowering trees.
Check price on Amazon Search eBayPlastic training pot
If the tree is still being developed, a training pot of about the same length is the better buy this year.
Check price on Amazon Search eBayDrainage mesh and tie-in wire
For the repot itself.
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Change something: another size · another style · start again.