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Broom

by Rudi Adam

This is one of the youngest styles developed in Japan, started in the early part of this century, and almost exclusively performed on the Zelkova (a form of Japanese Elm). The same tree shape occurs frequently in Europe where the English Elm grows naturally in this style, and on the Continent where the pruning of Willow trees for basket weaving results in a broom shaped tree. Many deciduous trees are suitable like all types of Ulmus (Elm), Trident maple and our indigenous Celtus Africana. There may be a few other species that have fine and straight twigs.

Inevitably as in all styles, there are a few variations:

Formal:

  • straight trunk right through to the apex with branches radiating outwards and upwards.
  • straight trunk, forking narrowly into two or three branches radiating upwards and outwards to form the broom.

These more formal styles are all created from young material, without major cuts or blemishes on the trunk.

broom-style-formal

Informal:

  • Created from advanced material, with the V-cut method.
  • Straight trunk, forking into four or five branches.
  • Leaning trunk with the trunk right through to the apex.
  • Leaning trunk with the forking branches pointing upwards.

Broom style is usually of slender trunk, only occasionally some heavy trunks are encountered.

In this case you must be sure to have the proportion of trunk to 'broom' correct.

There are two major ways to create broom-style.

1. From seedlings

broom-foliageIn spring, straight young seedlings are selected, roots inspected for even all round development, possible taproot removed, then planted into a comparatively shallow but wide container and trimmed to a height of 20-25cm. Rub off all but the top 3-5 buds. These are the future main branches and should therefore radiate in different directions.

These should be allowed to grow for a full season then trimmed back to 1/2 or 2/3 of the original trunk length. The following season, remove all but 2-3 buds, situated on or near the end and then allow to elongate.

Again, trim in mid season to 1/2 to 2/3 of the length of the main branches and allow to grow for the rest of the season. Branch forks should be narrow and may have to be corrected with wire if necessary.

Repeat this process with diminishing distances by nipping until final height is achieved. Overcrowded branch lets must be removed from time to time and unwanted buds rubbed off.

broom-style-cutSurface roots should remain 2 - 3cm under the soil level for the first 5-6 years in order to thicken them up adequately.

2. The V-Cut method

This method is used with older, advanced stock of the Ulmus family, usually with a much heavier trunk.

At a point which in height equals 3-4 times the diameter of the trunk, cut the top of the tree right off, not straight across but rather in a V shape, with the one side of the V longer.

This can be done late in winter. Then carve the heartwood out quite deeply by means of a drill and or carving chisels. Make certain not to damage the cambium. Now strap the outside of the trunk extending at least 1 - 2 cm above the cut area, with a stiff plastic or fiberglass sheet, held in place with a hose-clamp or twine. This will stop the formation of a callus to the outside of the trunk, which would form an enlarged area.

New sprouts will form from the cambium at the cut area. Root pruning at the same time would be advantageous in order to keep some sort of balance and prevent excessive growth.

broom-style-progressionDo not prune top growth for the first year unless one or two sprouts threaten to take over. The following winter prune all the sprouts to 2/3 of the trunk length, except the one nearest to the bottom of the V on the front of the tree. This sprout should be left unchecked until at least half the trunk thickness of the original has been achieved.

Cut back each year to 2/3 of the previous year IS growth, all cuts facing towards the center. After 3 - 4 years, growth should have slowed down to a manageable level and the strapping should now be removed (having been checked periodically and loosened as growth demanded). During this period thinning out of branches may be essential until only 3 - 5 are left.

broom-bonsai-treeTreatment thereafter is the same as with seedlings. The hollowed out area should to a large extent have healed over (the faster the growth of the branches, the faster the healing) and therefore growing in an oversize container for the early period is advantageous. Changing to a smaller container later will give you more control and fewer twigs.

The beauty of this style is the marriage by the tree between soil and sky, with the use of strong surface roots, and elegant twigs.

Broom style can in fact be one of the most elegant styles in bonsai.

Visit the Olive Grove Nursery webpage

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Random Bonsai Tip

If surface roots are unequally spread around the trunk or if they are lacking completely you can drill holes and insert match sticks or make deep scars around the base of the trunk on the side where the roots are needed below soil level. Apply hormone powder and sphagnum moss; cover with plastic and keep moist. Leave for 6 months to 1 year for the roots to develop.