太枝は三段切りで──裂けを防ぐ鋸の入れ方と、重い枝の下ろし方(The Three-Cut Method for Large Limbs with a Japanese Pruning Saw)

The Three-Cut Method for Large Limbs with a Japanese Pruning Saw

Cut a large limb in one go and its weight tears the underside of the branch base away from the trunk. This article shows, with illustrations, the three-cut method that prevents it, how to pull a Japanese saw, and how to lower a heavy limb on a rope, drawing on public pruning documents and a gardener’s field experience.

This is the eleventh article in our series on the pruning techniques of Japanese gardeners (niwashi, ueki-ya). The previous article covered karikomi-basami, the hedge shears. This one is about how to take off a thick limb safely without hurting the tree.

Cut it in one go, and the base tears

If you try to cut a thick limb off from above in a single cut, the weight of the limb pulls its tip down when the saw is about halfway through. The part still joined underneath cannot carry the load. It tears toward the base, pulling bark and wood away with it. The tear does not stop at the cut; it runs a long way into the trunk side.

Public specifications deal with this too. A thick limb is first cut some tens of centimeters above the intended final cut to lighten the tip, and only then cut back to the base. The purpose is to keep the limb’s own weight from tearing the base. The warning that cutting a large limb in one go tears the lower part of its base appears, with diagrams, in the street-tree pruning documents of Saitama Prefecture and the City of Sapporo.

Japanese public documents call this method nidan-giri (“two-step cut”). American sources call the same procedure the three-cut method. Only the way of counting differs; the three places where the saw goes are the same. This article counts the saw cuts and calls it sandan-giri, the three-cut method.

From our experience in the field, the thicker the limb, the more its weight comes onto the saw all at once just before the cut is finished. That is usually the moment the saw gets pinched or the limb tears. The three-cut method lightens the limb before that moment comes.

The three cuts

The three-cut method divides the saw work into three. First, a shallow notch is cut from underneath, away from the base (the first cut). Next, the limb is cut off from above, a little farther out (the second cut). Finally, the short remaining stub is cut at the base of the branch (the third cut).

The first cut is the shallow notch from below. Saw into the underside of the limb and stop partway through its thickness. Make it away from the base, not close to it. Position and depth vary between sources. American sources give examples of 6 to 12 inches (about 15 to 30 cm) from the base, and of 12 to 18 inches (about 30 to 46 cm). The depth in some examples is about one-third to one-half of the limb’s thickness. Japanese specifications say to cut some tens of centimeters above the intended final cut. From our experience, the thicker the limb, the farther from the base we make the notch.

The second cut takes the limb off from above. Put the saw directly above the first notch, or a few centimeters farther toward the tip, and cut downward. The limb breaks between the two cuts and falls. Because there is a notch on the underside, the bark underneath is not stripped toward the trunk as the limb breaks.

The reason for cutting from below first is to stop the direction of the tear. Without the notch, the tear runs from the upper cut a long way toward the trunk. With the notch, the tear stops there and does not reach the underside of the base.

The third cut removes the lightened remainder at the base. Cut just outside the branch bark ridge and the branch collar, without cutting into the collar and without leaving a stub. The reason for this position is explained in our article on the branch collar. The remaining stub is short and light, so you can hold its end with one hand and take its weight while you cut. The saw does not bind, and the cut does not tear at the last moment.

Do not leave the short stub from the second cut as it is. A stub eventually dies, and decay can advance into the trunk. The three-cut method is complete only when the third cut is made.

The method is for limbs too large to support by hand. The USDA Forest Service says limbs too large to support by hand are cut in three steps to prevent bark ripping. Some university sources use limbs over 1 inch (about 2.5 cm) or over 1.5 inches (about 4 cm) in diameter as a guide. A thin limb you can hold needs only one cut at its base.

Pull the saw

A Japanese saw cuts on the pull stroke. According to encyclopedias, all Japanese saws today are of the pull type, while saws elsewhere include push types. The USDA Forest Service also notes that many pruning saws are made to cut on the pull stroke. The teeth are set alternately left and right (asari), which makes the cut slightly wider than the blade and keeps the blade from binding in the wood.

From our experience, use the full length of the blade and put your strength into the pull. Ease off on the push. Moving the saw from the wrist bends the cut and makes the blade bind, so move it with the arm and shoulder. At the start, rest the blade lightly on the limb and pull short strokes to make a groove, then lengthen the strokes. The hand that supports the limb is never placed where the blade is going.

A saw also has its limits. The USDA Forest Service says a small pruning saw suits limbs up to about 10 cm in diameter, and that a chain saw suits thicker ones. Forcing a hand saw through a thick limb throws off your control and leaves a rough cut.

Lower a heavy limb on a rope

The three-cut method protects the cut surface, but the limb you cut off still falls. To keep it from hitting people, objects or nearby branches, pruned branches are not simply dropped; thick ones are cut to suitable lengths while hanging from a rope and lowered to the ground.

From our experience, put the rope on the limb tip before the second cut. The person holding the rope stands out of the way, not directly under the limb, and keeps the rope taut to decide the direction of fall. The person on the ladder concentrates on the saw, so agree on a signal for the moment of the cut. If a limb is too thick to reach safely from a ladder, do not force it; switch to an aerial lift or rope work.

The cut surface and its closing over the years

Finish the cut smooth with a sharp saw. A ragged cut hinders closure. A cut made in the third step, leaving the branch collar, is closed by the tree over time, which rolls tissue in around it like a ring. The USDA Forest Service also shows that a proper cut produces wound-covering tissue in a concentric ring.

The cut surface of a thick limb takes several years to close. From our experience, when you look at the cut a few years later and the ring has grown evenly on both sides, you know the position was right. The work of the three-cut method is judged not on the day of the cut, but years later. By the time the cut has shrunk to a small oval, almost no scar remains at the base of the branch, and it is hard even to tell that a limb was ever there. Preparing the way with the very first cut, so that the tree can close the wound on its own, is the gardener’s job.

The craftsman’s hand: read the weight of the limb first

Among craftsmen it is said that before putting the saw in, you walk around the tree, look up at the limb, and read its weight, how it hangs, and the way it will fall. The more twigs and leaves at its tip, the heavier the limb and the bigger its movement when cut. Before cutting, check that there is no person or object where it will fall, and decide where the cut limb will be lowered. Only then take the saw in hand.

Among craftsmen it is said that with a thick limb you stop after every stroke and watch how it moves. As the cut deepens, the limb sinks slightly and what you feel through the saw changes. Feeling that change with your hand keeps you from hurrying the cut. The three-cut method, done in three unhurried steps, is a form that protects the tree, and also keeps the person from getting hurt.

Among craftsmen it is said that a dull saw makes rough work. A blunt blade binds more easily and leaves a ragged cut. Checking the edge of the saw before cutting a thick limb is part of the job.

Frequently Asked Questions (Q&A)

Q1. What is the three-cut method?

A. A way of removing a thick limb with three saw cuts. Cut a shallow notch from below, away from the base; cut the limb off from above, a little farther out; then cut the short remaining stub at the base. Japanese public documents also call it “two-step cutting.” It keeps the weight of the limb from tearing the base.

Q2. Why cut from below first?

A. To keep the bark and wood on the underside from tearing toward the trunk as the limb breaks off. With a shallow notch below, the tear stops there and does not reach the underside of the base.

Q3. How far from the base should the notch from below be made?

A. Sources vary. American sources give examples of 6 to 12 inches (about 15 to 30 cm) and of 12 to 18 inches (about 30 to 46 cm) from the base. Japanese specifications say some tens of centimeters above the intended final cut. In the field, the thicker the limb, the farther out.

Q4. Is the three-cut method needed for thin limbs?

A. A thin limb you can support by hand needs only one cut at its base. The three-cut method is for limbs too large to support by hand. Some university sources use limbs over 1 inch (about 2.5 cm) or 1.5 inches (about 4 cm) in diameter as a guide.

Q5. What if the limb I cut off is heavy?

A. Cut thick limbs to suitable lengths while hanging from a rope, and lower them to the ground. Put the rope on the tip before the cut, and have the person receiving it stand out of the way, not directly under the limb. If a limb is too thick to reach safely, switch to an aerial lift or rope work.

Sources

– Saitama Prefecture, Civil Engineering Department. Street-tree pruning manual (December 2020), pp. 5-10, Fig. 5-6.
– City of Sapporo, Construction Bureau. Street-tree pruning technical guideline (fiscal 2016), p. 14.
– City of Yokohama. Common Specifications for Street Tree Maintenance Contracts (February 2026 edition), Article 41.
– USDA Forest Service. How to Prune Trees (NA-FR-01-95, revised 2012).
– ISA. Pruning Mature Trees (v03.2021; a public copy hosted by the City of Abbotsford).
– ANSI A300 (Part 1) Pruning (2001 edition; a public copy hosted by the City of Long Beach).
– Colorado State University Extension. Pruning Cuts (GardenNotes #612).
– Iowa State University Extension. What is the proper way to prune a large tree branch?
– Kotobank. “Nokogiri” (saw): Nihon Daihyakka Zensho and Sekai Daihyakka Jiten.

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