Exposed-root bonsai can be amazing compositions; we love the wild randomness of the roots and the crazy shapes that they make as our trees age and mature.
Exposed root has been well explored in Japanese bonsai and in Chinese bonsai. To the extent that you can see at least the junction of the main roots and the trunk when it is potted, all bonsai should be exposed root. While creating exposed root bonsai from young material can take a few years, the process is fun and well worth the time. If you're inclined to some experimentation and have some good growing skills, here's how you can do it!
The basic process that allows you to expose the roots to air is to create a deep container with sides you can cut away and then plant your young tree in. After the roots get larger, you slowly remove that container. Allowing your tree to grow wild helps speed along the process of enlarging the roots, so be prepared to allow some extra space!
- Year 0 - Create a seedling apparatus, an elongated container on top of a growing container, to allow the roots to elongate. Use coarse soil particles in the top tube/container so that the roots have to wiggle to go down. A fine layer of small soil at the top is advisable to keep the existing roots alive. Prior to planting, trim roots short if they are longer to encourage more branching near the base and prevent awkwardly circling roots.
- Year 1-2 - Grow for the majority of a year, then begin exposing roots. Depending on the species, climate, and speed of your growth you may only remove a few inches at a time. You can keep soil particles between the roots or remove them. The length of time you leave the roots protected can have an effect on the total number of the roots, and therefore the size of each root in the long term. If you are in doubt, leave the roots with some protection for a longer period.
- Year 2-3 - Once a significant portion of the roots are exposed, begin shaping them, using bonsai wire, staking, or other means. Consider introducing twists; remember that you want the roots to look interesting and harmonious. Because no branching comes from the roots, don't forget to bend down branches from the actual trunk.
- Year 4+ - Allow the plant to grow vigorously so that more wood is created and the roots mature further. Once the roots reach the desired size, begin more controlled training of the branching and remove long growth.
Some species naturally lend themselves to the exposed root style more than others due to the growth pattern and character of their roots. Japanese Black Pine is a prime candidate as are many other pines. Japanese and Trident Maples both work reasonably well also.
- Trident- Create good solid wood, roots fuse with themselves in interesting ways.
- Black Pine - form solid roots, bark extends nicely over time.
- Juniper - Roots form wood slowly, stay flexible. Although possible, it takes a long time!
- Crabapples, Quince etc. - more difficult because the roots are sensitive, but can be quite interesting since they create leaf and branch growth from the roots.
- Ficus - Similar to Trident Maple, many Ficus species fuse well and create good woody roots.
The core concept in exposed root is that the roots aesthetically replace the trunk, or augment the lower portion of it. With this in mind, the shape and flow of the roots is key to creating a good composition:
- Make sure the base of the roots entering the soil is not smaller than the portions above it, creating reverse taper.
- The roots should have character (e.g. not straight).
- The roots should exit the trunk gently, not at right angles, or like an informal upright and then plunging vertically afterward. Wrap roots that stick out to make a clump.
- Gentle harmonious movement in the roots can be pleasing.
- Avoid straight up compositions, or allowing the roots to bow outward.
- Make small corrections - in illustration #6 below, the base should be widened by moving roots away from each other.
- While roots spreading in all directions can be interesting, it will often look awkward and odd.
- Illustrations 8-11 below: Cascade and semi-cascade are good styles for exposed root because they allow foliage to be closer to the interest in the roots. Some roots that are a bit wild looking can be interesting.
- Illustrations 8-11 below: Match the pot to the style of tree just like you might for any other composition.
ExamplesHere's one of our Bonsaify exposed root bonsai trees:
If you're interested in learning more, we invite you to register for our "Exposed Root Bonsai" live online seminar: https://www.bonsaify.com/products/live-online-seminar-exposed-root-pines-1.