切り戻し剪定とは──芽の上と分かれ目で切る、枝を短くする庭師の技|樹木医が図解(Kirimodoshi: Reduction Cuts to an Outward Bud or Lateral)

English: Kirimodoshi — Reduction Cuts to an Outward Bud or Lateral in Japanese Pruning

Kirimodoshi sentei (切り戻し剪定), “cutting back”, is pruning in which an overgrown branch is shortened by taking it back to just above a bud, or to a side branch at a fork. Which bud and which fork you cut to decides the direction of next year’s growth and the size of the tree. In this illustrated article, a Jumokui (tree doctor) explains where and at what angle to cut, how thick the remaining branch must be, and when to cut, with reference to Japanese public pruning standards and sources from abroad.

This is the fifth article in our series on the pruning techniques of Japanese gardeners (niwashi and uekiya). The previous article, on eda-nuki, covered removing branches at their point of origin. This time the subject is the other basic cut: shortening a branch without removing it.

What kirimodoshi is: taking a branch back to a bud or a fork

There are two places a branch can be shortened to: a bud, or a side branch at a fork.

Cutting a young shoot just above a bud is kiritsume sentei (shortening, or heading). A new shoot grows from the bud just below the cut and becomes the new branch tip. Clipping hedges and rounded shrubs belongs to the same family.

Taking a thicker branch back to a side branch that divides from it partway along, and cutting off the longer branch at the fork, is kirikaeshi sentei. Depending on the region and the document it is also called kirimodoshi sentei, and it is the basic method for keeping a crown within its target outline (City of Yokohama specification; Saitama Prefecture Street Tree Pruning Manual).

In this article, I use “kirimodoshi” for both. If eda-nuki, removing branches at their origin, adjusts the density of a tree, kirimodoshi adjusts its size and the direction of its branches. In garden work, the two are combined within a single tree.

Cutting above a bud: just above it, sloping with it

The cut is made just above the bud, following the bud and sloping so that the side opposite the bud is slightly lower (Tokyo Metropolitan Government, Street Tree Maintenance Plan; Saitama Prefecture manual). Japanese public documents give no distance in millimetres, but sources abroad give no more than 5 mm above the bud (Royal Horticultural Society) or 1/4 inch, about 6 mm (Virginia Cooperative Extension) as a guide.

If the cut is made too far from the bud, the piece of branch left above it receives no nourishment and dies back. If it is made too close or too steeply, the bud itself dries out and weakens. A cut square across the branch can also die back from the corner opposite the bud (Saitama Prefecture manual). From our experience in the field, a stub left above a bud turns brown over the winter and remains as a small horn, quite noticeable up close.

Thin branches are cut with ueki-basami (Japanese garden scissors). The blades are set slightly above the bud, angled with it, without touching it. Supporting the tip of the branch lightly with the other hand keeps the branch from slipping away at the moment of cutting, so the cut is less likely to be crushed.

Cutting to an outward bud: choosing the direction of the next branch

When a branch is cut above a bud, the bud just below the cut starts to grow as the new tip. The bud at the end of a shoot holds back the growth of the buds below it (apical dominance); when the tip is cut, that restraint is lifted and the remaining buds start to grow.

So the bud you cut to decides the direction of next year’s branch. Cut above a bud facing the outside of the crown (sotome, an outward bud) and the new shoot grows outward, spreading the form; cut above a bud facing inward (uchime, an inward bud) and the shoot grows inward, keeping the form compact (Saitama Prefecture manual). On trees grown in a natural form, the cut is normally made above an outward bud (Tokyo Street Tree Maintenance Plan).

From our experience in the field, a branch cut above an inward bud runs into other branches inside the crown within two or three years and becomes a source of crowding. The inward-growing and crossing branches described in our imi-eda article are often born this way. Where a branch spreads too far sideways, or grows toward a neighbouring tree or a building, an upward- or inward-facing bud may be chosen on purpose to bring the branch back. The outward bud is the rule; which bud to choose is decided by looking at the space around that branch.

Cutting back to a fork: the remaining branch should be at least one-third as thick

When a thick branch is shortened, it is taken back not to a bud but to a side branch at a fork. A branch that has grown beyond the target crown outline is cut off at the point where a side branch divides from it on the inside, and that side branch is left to carry on (Tokyo Street Tree Maintenance Plan).

What matters here is the thickness of the branch that remains. It should be at least one-third the diameter of the branch being cut (NILIM, Guide to Preventing Street Tree Failure). Some American extension sources suggest one-half where possible. If the remaining branch is too thin, it cannot take over as the tip, and several vigorous water sprouts burst out near the cut. Thick branches have almost no buds to begin with; when they are cut, new buds appear irregularly around the cut (Saitama Prefecture manual). Even if the cut is made at a fork, the tree responds much as it does to butsu-giri, “chopping” branches off at arbitrary points, which public standards in Japan say should not be done as a rule.

Making a tree smaller: over several years, a little at a time

To make an overgrown tree smaller, the same cut back to a fork is used. Taking the outer branch tips back, one by one, to forks with outward-growing branches makes the tree a size smaller while keeping its form.

But the tree is not reduced a great deal at once. Height and spread are reduced in a planned way over several years (Tokyo Street Tree Maintenance Plan). For street trees, rebuilding the form under a management plan of about three to five years is also described (Saitama Prefecture manual). As a guide in our own work, one cut takes a branch back no further than one or two forks in from its tip. Going further means the remaining branch becomes too thin, and the water sprout problem described above appears.

As for timing, the right season for deciduous trees is around November to February, after leaf fall, and for evergreen trees around September to October, with June to July also possible (City of Yokohama specification). Evergreens from warmer regions, such as camphor trees, are sensitive to cold, so cutting back in midwinter is avoided. Pruning when young leaves are opening in spring, and hard pruning in summer, put a heavy burden on the tree and are not done (Saitama Prefecture manual). Now, in October, is the time for cutting back evergreens. Deciduous trees are worked on after leaf fall, when the branches and buds can be seen clearly.

The craftsman’s eye: reading the buds before the scissors go in

Among Japanese gardeners it is said that kirimodoshi is not the work of cutting this year’s branch, but of deciding the direction of next year’s. Before the scissors go in, the gardener takes the branch tip in hand and looks at which way the bud faces, and at what space the shoot from that bud will fill in two or three years. While looking at a small bud in the hand, the mind is drawing the branch structure several years ahead.

This way of seeing works only on young branches that still have buds. That is why gardeners guide the direction of branches little by little with cuts above buds while a tree is young, so that a situation where thick branches have to be cut never arises. Cutting back a thick branch at a fork is, I think, a means of correcting a branch that guidance did not reach in time.

Another thing gardeners care about is the line of the branch tip after cutting. On a branch cut cleanly above a bud, a new shoot takes over the tip the next year, and it becomes impossible to tell where it was cut. A branch taken back to a fork, too, if the remaining branch grows naturally outward, ends in a tip that tapers off naturally. No cut in sight, and no branch tip that looks cut. The care that Japanese gardeners call “shizenfu” (natural style) is the accumulation of these individual cuts.

How kirimodoshi corresponds to reduction and heading cuts: for readers outside Japan

Kirikaeshi, cutting back to a fork, corresponds to the reduction cut in arboriculture. Colorado State University Extension describes a reduction cut as removing a larger branch back to a smaller-diameter side branch, and says the side branch should be at least one-third, preferably one-half, the diameter of the branch removed; cutting back to anything thinner is treated as a heading cut and invites water sprouts. The Japanese kiritsume, cutting above a bud, corresponds to the heading cut.

The American pruning standard ANSI A300 (2001 edition) defines heading as cutting a currently growing or one-year-old shoot back to a bud, and requires, when reducing a crown, that the remaining lateral be large enough to assume apical dominance. The USDA Forest Service guide “How to Prune Trees” says crown reduction, sometimes called drop crotch pruning, is preferred to topping, while describing it as a method of last resort.

One of the pillars of our approach, GREEN MANAGEMENT, is the integration of scientific knowledge (arboriculture) with field experience. How far a branch can be taken back is decided by how the tree works; which bud to stop at is decided by the gardener’s eye. Kirimodoshi, I believe, is a technique in which the two meet in a single cut.

Frequently asked questions

Q1. What is kirimodoshi pruning?

A. It is pruning in which an overgrown branch is shortened by taking it back to just above a bud, or to a side branch at a fork. It includes kiritsume (cutting a young shoot above a bud) and kirikaeshi (taking a thick branch back to a fork and removing the longer part). It adjusts the size of the tree and the direction of next year’s branches.

Q2. How far above a bud should the cut be?

A. Just above the bud, following it and sloping so that the side opposite the bud is slightly lower. Sources abroad give no more than 5 mm, or about 6 mm (1/4 inch), above the bud as a guide. Too far and the stub dies back; too close and the bud weakens.

Q3. How are outward and inward buds used?

A. The bud just below the cut becomes the new tip, so cutting above an outward-facing bud sends the branch outward and spreads the form, while cutting above an inward-facing bud sends it inward and keeps the form compact. On trees grown in a natural form, the cut is normally made above an outward bud.

Q4. Is there a rule for the thickness of the branch left when cutting back to a fork?

A. The remaining branch should be at least one-third the diameter of the branch being cut. If the cut goes back to anything thinner, the remaining branch cannot take over as the tip, and several water sprouts tend to appear near the cut.

Q5. Can an overgrown tree be made smaller in one go by cutting back?

A. Reducing it a great deal at once puts a heavy burden on the tree, produces many water sprouts and ends up spoiling the form. Height and spread are reduced in a planned way over several years. The right season is around November to February for deciduous trees and around September to October for evergreens.

Sources

– Tokyo Metropolitan Government, Bureau of Construction. Street Tree Maintenance Plan. December 2021.
– Tokyo Metropolitan Government, Bureau of Construction. Standard Specification for Street Tree Maintenance (Green Space Management). April 2013.
– City of Yokohama, Road and Highway Bureau. Common Specification for Street Tree Maintenance Contracts. February 2026.
– National Institute for Land and Infrastructure Management (NILIM). Guide to Preventing Street Tree Failure, 2nd edition. Technical Note No. 1059, 2019.
– Saitama Prefecture, Road Environment Division. Street Tree Pruning Manual. December 2020.
– American National Standards Institute. ANSI A300 (Part 1)-2001 Pruning. 2001 (not the current edition).
– Bedker, P.J., O’Brien, J.G., Mielke, M.E. How to Prune Trees. USDA Forest Service, NA-FR-01-95, 1995 (revised 2012).
– Colorado State University Extension. CMG GardenNotes: Pruning (#612 Pruning Cuts).
– Schieffer, J., Elmendorf, W. Pruning Landscape Trees. Penn State Extension, updated 5 November 2021.
– Virginia Cooperative Extension. A Guide to Successful Pruning: Pruning Deciduous Trees. SPES-403P.
– Royal Horticultural Society. How to prune roses.

Masatoshi Nakamura
Jumokui (Tree Doctor), Toshi Landscape Co., Ltd., Tokyo