Exposing the secrets of “Exposed Root” bonsai trees.

Posted by on Mar 16, 2020 | 2 Comments
Exposing the secrets of “Exposed Root” bonsai trees.

It’s no secret that exposed root bonsai can be amazing compositions; there’s something about the wild randomness of the roots and the crazy shapes that is really appealing.

Exposed root was on my mind from the first time I picked up an old Kinbon magazine and saw the style in photos of Japanese show trees. While studying with Boon, one of my first trees went from having a slightly odd base to having more exposed roots that had been hidden in the soil.

Process

The basic process that allows you to expose the roots to air is to create a container that allows the roots to elongate vertically, and then slowly remove that container while keeping the growing tips safely in the soil. Use of vigorous sacrifice branching helps speed along the process of wood production that leads to the roots being strong enough for the tree to hold itself up on top of a bunch of once-tiny roots.

  • Year 0 – Create a seedling apparatus, an elongated container on top of a regular growing container, to allow the roots to elongate. Use coarse soil particles in the top tube/container to create movement in the roots. A fine layer of small soil at the top is advisable to keep the existing roots alive. 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 vigor 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 – you can use wire, staking or other means. Consider introducing twists etc, remember that this will be your trunk. 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.

Species

Some species naturally lend themselves to the exposed root style more than others due to the growth pattern and character of their roots. Similar to root-over-rock, Japanese Black Pine is a prime candidate as are many other pines. I have made Bristlecone pines, Japanese red pines and black pines successfully into exposed root compositions. Japanese and trident maples both work reasonably well also. Among species that I consider more difficult are oak, juniper, cypress and members of the rose family like crabapple and quince varieties.

Trident – Create good solid wood, roots fuse with themselves in interesting ways

Black Pine – form solid roots, bark extends nicely over time.

Kishu Juniper – Roots form wood slowly, stay flexible. Although possible, takes much longer.

Rose Family – crabapples, quince etc – more difficult due to dieback. 

Azalea – Many imported azaleas are exposed root. They are available from most importers.

Ficus ssp. – Similar to trident maple, many ficus species fuse well and create good woody roots.

Young Japanese black pines in spring 2016, after creating exposed root apparatus.

Aesthetics

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.

  • 1. Make sure the base of the roots entering the soil is not smaller than the portions above it, creating reverse taper.
  • 2.The roots should not be straight, and lacking character.
  • 3.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
  • 4.Gentle harmonious movement in the roots can be pleasing.
  • 5.Avoid straight up compositions, and avoid allowing the roots to bow outward
  • 6.Make small corrections – in 6 below, the base should be widened by moving roots away from each other.
  • 7.While roots spreading in all directions can be interesting, it will often look awkward and odd.
  • 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.
  • 8-11 below: Match the pot to the style of tree just like you might for any other composition.

Examples

Here are some examples of exposed root bonsai that I have created, and process photos for some of them.

Trident Maple – 2013
Same trident maple in 2016 – note the large sacrifice branch.
Cascade exposed root pine from Kokufu-ten, 2016, Tokyo, Japan.
Upright Japanese White Pine exposed root from Kokufu-ten, 2016, Tokyo, Japan.

If you’ve read this far and are wondering what in the world is going on with the pines in the first image at the top, then rest assured that this was only a temporary situation. I quickly tucked them all into soil enclosures after shooting the photo. However, note that it is a good illustration of part of the process.

Good luck with growing your trees!

2 Comments

  1. Trunk Splitter
    March 29, 2020

    A great article. Thanks for sharing.
    I take note because I have been trying to do this for a long time with thunbergii pines.

    There is no bonsai if there is not a great love for nature. I started growing trees in my garden and now I want to do it in pots. Thanks for the ideas.

  2. Nha Le
    April 14, 2020

    Great article. I’ve been wanting to experiment with this. Thank you for sharing.