When assessing bonsai trees whether to judge, buy or just reviewing your own, to develop them or set up a display there are a range of criteria that can be considered. Some may be conflictual and there may be many rules, but some rules are always meant to be bent a little or broken.

Here are some pointers to get you started…

General condition / health of bonsai tree

  • Good leaf colour if evergreen or when in leaf as a broadleaf
  • Even density of foliage if in leaf
  • Good vigour
  • No damage structural form so no broken branches or stems or missing sections, no wire scars, no unsightly bark or pruning wounds
  • No damage to foliage so no split leaves, damaged leaves, wilting, signs of ageing
  • Healthy appearance for tree species
  • Good density of buds if winter image


  • Actual age of the tree if authenticated and try to obtain some guide to the age if possible
  • Bonsai tree image and the impression is correct for the age presented
  • Old age is beautiful and the tree should capture the character of a tree growing in nature
  • Stem diameter in proportion to height of tree & spread of crown
  • Signs of aging present for species include bark fissures, thick trunk and or well developed crown
  • High level of ramification, dense branching structure with balance
  • Young trees have ascending branches so the branches near and in the apex can be horizontal or ascend since this is the young part of the tree

Freedom from pests & diseases

Therefore it is important to check for the following pests and diseases:-

  • Scale insect
  • Mealy bug
  • Fungal infections
  • Rusts
  • Red spider mite
  • Vine weevil
  • Other pests, diseases, viruses or fungal infections

Origin & difficulty of cultivation

The background and origin of a bonsai tree should be considered and here are a few things to review:-

  • Tree species that require higher temperature cultivation like tropical trees
  • Tree species that require greater care in watering
  • Tree species that are difficult to grow under ‘normal conditions’
  • Bonsai cultivated by air layering, grafting alternative root stock or fused form if authenticated
  • Bonsai grown from seed if authenticated
  • Are Yamadori (collected from wild) with permission and nota protected species in that country
  • Are grown from start by exhibitor or trader


  • Relative rarity of tree species
  • Unusual cultivar or variety


Look at how the tree is presented and does the presentation do the tree justice?

  • Refinement of presentation
  • Absence of weeds and algae on the compost surface
  • Absence of inappropriate flower remains or leaf debris
  • Appropriate top dressing i.e. use of moss
  • Foliage clean and free from residues
  • Labelling of bonsai tree correct species
  • Overall image presented (aesthetics)
  • Any wiring or guys should be unobtrusive

Bonsai pot / cultural medium

  • Correct colour for bonsai tree – coloured glazed should be used for flowering & fruiting trees & colour to complement flower colour
  • Does the style, shape and size of the pot fit the character of the tree?
  • Correct dimensions of the pot for the bonsai tree
  • Depth of pot should be set by the diameter of the trunk except for cascades
  • Width of the pot for tall trees should be 2/3rds the height of the tree
  • Width of the pot for short trees should be 2/3rds the spread of the tree
  • Bonsai pot and tree in harmony
  • Tree should be placed behind the mid line of the pot, & to the left or right of the centre line
  • Uprights with little movement = rectangular pots
  • Informal uprights = oval or round pots
  • Oversize trees = deep rectangular pots
  • Cleanliness of bonsai pot
  • Level of the tree in the bonsai pot – soil to tree transition
  • Stability of tree in pot & pot on display
  • Soil should be uniform
  • Tree not over or under watered

Bonsai stand / Tokonoma

  • Appropriate stand for size of tree and pot
  • Suitable colour
  • Stand made from suitable material
  • Complimentary ornament / ascent
  • Scroll if used suitable to design
  • Overall impact of Tokonoma

Overall form

  • Correct form for tree species (naturalness)
  • Tree of accurate size for class
  • Scale appropriate (Height of tree 6x diameter of trunk)
  • Only one apex

Roots / Nebari

  • Nebari present
  • Roots should radiate from the flare
  • No eye poking roots (directly at viewer)
  • Roots should be visible on the surface of the soil.
  • Do they look natural?
  • Anchor wiring should not be visible


  • Trunk should flare at base to visually anchor the tree
  • Taper correct – it should taper as it ascends (no reverse taper acceptable)
  • It should be wider near the base and become gradually thinner toward the top
  • Should lean slightly towards viewer and not move back on itself

Style of bonsai

  • The informal upright style (Moyogi)
  • Slant-style (Shakan)
  • Semi cascade
  • Drift wood
  • Raft-style (Netsuranari)
  • Literati style (Bunjin-gi)
  • Group or forest style (Yose Ue)
  • Broom style (Hokidachi)
  • Multi-trunk style (Ikadabuki)
  • Shari style (Sharimiki)
  • Growing-in-a-rock (Ishizuke)
  • Free form style

 Flowering / fruiting bonsai trees

  • Aesthetically pleasing to the eye
  • Fruits firm / flowers fresh
  • Good colour of fruit / flower
  • Density of flowers or fruits even throughout bonsai tree & do not overwhelm exhibit in size or quantity
  • No. of flowers open should be in proportion to the size of the exhibit