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The 'Rules' of bonsai 

by Brent Walston


As in all arts, bonsai usually conforms to a set of conventions, guidelines, or 'rules'. Rules is probably the worst word of the three to describe what most artists do to create bonsai, but it is the word that most people use. These rules are not cast in stone and are frequently broken as the situation demands, but they are excellent guidelines for the creation of beautiful bonsai, and are invaluable to persons learning bonsai. They simplify what otherwise would be a bewildering set of decisions.

These rules mostly come from the Japanese culture of bonsai over the last few centuries. They are an analysis of what 'works', and what 'doesn't work' in the creation of bonsai. Almost anyone can create a decent looking bonsai by following these rules, whether or not one has any native talent. That is the beauty of this distillation. Of course, very good bonsai will still depend upon talent, experience, inspiration, and serendipity, as well as a general conformity to the rules of bonsai.

Trunk and Nebari Rules

  1. Height should be six times the caliper of the trunk.

  2. Trunk should lean slightly toward the viewer.

  3. Trunk should flare at base to visually anchor the plant.

  4. Roots should radiate from the flare.

  5. No eye-poking roots (directly at viewer).

  6. Apex should lean toward viewer.

  7. Trunk should taper as it ascends. No reverse taper.

  8. Grafts should match understock and scion so that they are unobtrusive, or be placed low enough to disappear into the nebari.

  9. Curves in trunk should not result in 'pigeon breast' (roundness toward viewer).

  10. Apex should finish in the direction set by the base. 'Flow' should be maintained.

  11. Trunk line should not move 'back on itself'. This is one of my rules and difficult to explain. It relates to the flow of the tree. A trunk line that moves back on itself creates a 'C' curve.

  12. For formal and informal upright, the apex should be over the base.

  13. In informal uprights, too many 'S' curves will be tiresome.

  14. As a tree ascends the curves should be closer together (related to branch placement).

  15. A tree should have only one apex.

  16. Twin tree trunks should divide at the base, not higher up.


  1. No crossing branches, or branches that cross the trunk.

  2. No eye-poking branches (pointed directly at viewer).

  3. First branch should be placed approximately one third the height of the tree.

  4. Succeeding branches placed at one third the remaining distance to the top of the tree.

  5. Branches go on the outside of the curves (No belly branches).

  6. Branch caliper should be in proportion to the trunk. Branches that are thicker than one third the trunk caliper will be too thick.

  7. First branch should be left (or right), second branch right (or left), third branch should be back branch.

  8. Branches should visually alternate, no parallel branches.

  9. Branches should diminish in size and caliper as they ascend.

  10. There should be space between the branches to 'Let the birds fly through'.

  11. First and second branches (Left and Right branches) should be placed forward of the mid line to 'invite' the viewer.

  12. First, second, and third branches are approximate 120 degrees apart, with the back branch not directly behind the tree.

  13. Only one branch per trunk position, no 'wheel and spoke' or whorled branches, or bar branches (branches directly opposite each other).

  14. Branches should create an outline of a scalene triangle with the apex representing God, the middle corner man and the lower corner earth.

  15. Secondary branches should alternate left and right and follow the rules of main branch placement, except there should be no secondary branches moving up or down. This creates the foliage pad.

  16. To create the illusion of an old tree, wire the branches down. Young trees have ascending branches. The branches near and in the apex can be horizontal or ascend since this is the young part of the tree.

  17. Branches for cascades generally follow the rules for uprights, except that the trunk moves down.

  18. In twin trees, there should not be branches between the trees which would cross the trunks. The outside branches of both trees creates the triangle of foliage.

  19. A jin should not be hidden in foliage.


  1. The tree should be placed behind the mid line of the pot, and to the left or right of the center line.

  2. The depth of the pot should be the caliper of the trunk, except for cascades.

  3. Colored glazed pots should be used for flowering and fruiting trees and the colors should complement the flower color.

  4. The width of the pot should two thirds the height of the tree. For very short trees, the width should be two thirds the spread of the tree.

  5. Style of the pot should match the tree. Uprights without much movement should be in rectangular pots, informal uprights with a lot of trunk movement should be in oval or round pots. Massive trees should be in deep rectangular pots.


  1. Soils should be uniform, not layered. (New rule, you will still find controversy).

  2. Fertilize full strength. (New rule, there will be controversy).

  3. Water from above, not by submerging the bonsai, this will prevent the buildup of salts.

  4. Increase humidity by using a tray of pebbles and water or by keeping the area under the bench wet, not by misting. (This is my rule, there will be controversy. Misting increases the salt buildup on the leaves, and does practically nothing to raise humidity.)

  5. Remove most of the 'fines' from any soil mix, using only coarse particles.

  6. Water when the plants need to be watered, not by a fixed schedule.

  7. Keep temperate climate plants outside. Only tropical and subtropical plants (for the most part) are suitable for indoor bonsai. Temperate climate plants must be given an appropriate period of cold dormancy if they are to be kept indoors.

And finally

John Naka's book Bonsai Techniques I, 1973, Bonsai Institute of California, is by far the best treatise on the 'rules' of bonsai that I have found. Anyone can create convincing bonsai by following these conventions. Once they are mastered, you can begin to create without thinking about 'rules'.

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