When learning how to create bonsai, we’re confronted with some obvious questions about how to make them look right. My previous three posts covered the basics of design, mostly from the standpoint of composition and key “tricks” we use in fooling the brain. All well and good, but for those of us who tend toward numbers and technical factors as a means to the art of bonsai, it’s really important to know certain concepts and proportions that lie somewhat outside the realm of pure artistry. So with that said, here’s a listing of useful numbers and other factoids that will help you make presentable bonsai as you work your way toward true artistic expression.

• Tree size (height): from an inch tall to roughly 48 inches tall.
• Basal trunk thickness: from about a quarter-inch to the practical limit of roughly 12 inches.
• Height to basal trunk thickness ratio: 2:1 to roughly 12:1 for most styles; bunjin/literati and cascade tend to be greater.
• Foliar spread: from about half to two-thirds the height of the tree.
• Branch placement: first branch roughly one-quarter to one-third the way up the trunk from the soil; second branch on the opposite side of the trunk or (less commonly) in the back of the tree roughly 33-40% up the trunk from the soil; third branch in the back of the tree or (less commonly) on the opposite side from the first branch, roughly 40-50% up the trunk from the soil. Branches continue upward in a “spiral staircase” fashion, getting closer together as they go up the tree. Note: all of these rules are guidelines. Stick with them as closely as you can when starting out; stray from them artistically later on.
• Tree placement in pot: off-center toward the side featuring the first (lowest) branch, slightly toward the rear of the pot.
• Depth of pot: roughly the basal trunk thickness above the root crown. (Root crown: for trees with a flaring base, where the flaring roots merge into the main body of the trunk.) For semi-cascade trees, the pot is typically about three times the basal trunk thickness. For cascade trees, the pot is typically quite tall and typically several times the basal trunk thickness. Cascade pots are usually two or three times as tall as they are wide.
• Length of pot: roughly half up to two-thirds the height of the tree.
• Width of pot: for oval and rectangular pots, usually based on the length of the pot and more or less compliant with the “golden ratio” – meaning roughly 1.61 times as long as wide. So for a 9″ oval or rectangular pot, it’ll be visually pleasing if it’s about 5.6″ wide.
• Color of pot: brown unglazed is suitable for all trees, colored glazed pots work best for deciduous trees. Sometimes you have to experiment to get the pot just right. Often a tree’s pot will change periodically during its life as a bonsai.

Here’s my nice riverflat hawthorn, about one season away from being “finished.” Let’s look at some numbers as they relate to this tree:

The tree is 31″ tall. The foliar spread is 25″. The trunk base is 3″ in diameter above the root crown. The pot is 3″ deep and 15.5″ in length. It’s glazed a beautiful green color. The first branch on this tree is roughly 25% of the way up the trunk from the soil surface. The second branch is roughly 40% of the way up the trunk. The rest of the branches are arranged more or less in a spiral manner up the trunk, becoming more plentiful as they reach the crown. The tree is potted slightly to the right of center of the pot, on the side of the first branch, and slightly to the rear of the pot.

So there you have Bonsai by the Numbers. Let me know what you think.