Niwaki GR Pro Secateurs vs ARS VS-8Z for Thinning a 60-Stem Wisteria

By late summer, a long-trained wisteria can turn a pergola or wall wire into a tight mass of whippy laterals. Both the Niwaki GR Pro and the ARS VS-8Z will cut a 12mm wisteria whip cleanly when new. The useful comparison starts deeper into the session, around the fortieth cut, when hand pressure, blade entry, and sap around the pivot begin to matter more than the first impression at the bench.

The 60-stem job, cut by cut

A mature wisteria pruned twice a year, once in July and again in February, presents a particular cutting profile. The July thin is mainly current-season lateral growth, green to semi-lignified, usually 5mm to 12mm at the cut point. That wood is soft, and a tired or dull edge tears the bark and leaves a ragged collar.

February changes the feel of the work. Retained spurs and older basal suckers have hardened by then, commonly to 14mm to 20mm, and some are pressed awkwardly against support wires or pergola timber. Those positions force angled cuts, often with only partial jaw closure.

The ARS VS-8Z has a 21mm rated cutting capacity and a high-carbon steel blade hardened by ARS to around 63 HRC. On hardened February growth, it bites without demanding much extra pressure from the operator, a detail that shows up when dozens of similar cuts follow one another. Its chrome-plated finish also sheds wisteria sap better than an uncoated blade, keeping the pivot cleaner through a long session.

The Niwaki GR Pro has a slightly narrower blade profile and a listed capacity in the same 20mm range. Its finer tip is well suited to July thinning, especially inside a crowded spur cluster where one lateral needs to come out and the three beside it need to stay. On dormant wood above 16mm, the GR Pro still closes properly, although the hand load rises faster than it does with the ARS.

After a full 60-stem prune, the pattern is clear in use. The VS-8Z carries the February hardwood work with less squeeze fatigue, while the GR Pro earns its place earlier in the year, where tip placement in congested green growth saves cleaner spurs.

Spring design and where sap gets in

The ARS VS-8Z uses a coil spring seated in a channel below the pivot. The Niwaki GR Pro uses a similar coil arrangement. With wisteria, the important variable over a season is sap, because July cuts bleed freely and the residue dries into a hard amber film.

On the VS-8Z, the spring sits in a slightly more open channel. A rag and a little light oil can clear the pivot area quickly after a sappy session. The GR Pro spring is set closer against the handle casting, so residue tends to collect in a pocket that a rag cannot reach properly. After heavy use, a full pivot strip is the more thorough fix for that buildup.

Sharpening the carbon steel edge

Both tools use high-carbon steel blades, and both take a whetstone edge in a way that stainless Felco blades resist. The sharpening method is the same one used on a Japanese sickle, or kama: work the bevel side, keep the flat back flat, and remove the wire edge from the reverse with one flat pass at the end.

On the VS-8Z, the factory bevel sits at roughly 20 to 25 degrees. A 1000-grit waterstone restores a working edge in six to eight strokes per session. If July green wood begins tearing instead of slicing, a 3000-grit pass refines the edge enough for cleaner cuts.

The safest way to hold the blade is to let the existing bevel lie flat on the stone. The stone then finds the angle already ground into the tool. Grinding a new angle wastes steel and tends to round the cutting line, especially when the blade has only lost a little bite from sap and light wear.

The GR Pro takes the same treatment. Niwaki sells a crean mate rubber block for rust and sap-film removal, and that block clears amber wisteria residue from the flat back without abrading the steel. On a kama, the same block matters even more, because the edge is single-bevel and rust on the flat back spoils the cut.

Use the block along the blade in the direction of the edge, not across it. After that, return to the bevel with the 1000-grit stone. The job is small if it is done often; a neglected blade asks for more metal removal and loses the crisp factory line sooner.

The wire edge is the step most often left unfinished. After bevel work, set the back flat on the stone and make one light pass on the reverse. That folds off the burr. If the burr stays in place, the first few wisteria cuts feel sharp, then the edge collapses because the burr was doing the cutting.

A note on the Felco 8 alternative

The Felco 8, with its rotating handle, suits gardeners with grip or wrist issues. Its replaceable-blade system can outlast both Japanese tools over years, and its stainless blade tolerates wet conditions well, though it does not take as keen a whetstone edge as the carbon steel used by ARS and Niwaki.

Rust, storage, and the trowel problem

Carbon steel gives both secateurs their clean cut and also gives them their main weakness. Left wet in a shed through a damp autumn, they rust. A Sneeboer trowel, forged from the same broad family of high-carbon steel, shows the same failure mode after a season left uncleaned in heavy soil: pit rust along the working edge.

The removal method carries across the secateurs and the trowel. For light surface bloom, a green rubber block or fine steel wool with a drop of camellia oil lifts the rust in a couple of minutes. For pitted rust on a neglected Sneeboer trowel edge, a citric acid soak works well: roughly 30g of powder to a litre of warm water for two hours dissolves the iron oxide without cutting into the parent steel the way a wire wheel can. Rinse, dry immediately, and coat the tool with camellia oil or a light machine oil before storage.

Prevention is simpler than repair. Wipe the blade after the wisteria session, because dried sap holds moisture against the steel for longer than the shed air alone. A secateur stored with sap on the blade already has the start of a rust patch. Soil left on a carbon-steel trowel over winter creates the same chemistry, and the working edge suffers first.

Both the VS-8Z and the GR Pro benefit from a monthly drop of oil at the pivot during the growing season, when they are cutting sappy wood weekly. In winter, after the February thin, a heavier coat and a dry drawer give better protection than a spray-on product that flashes off in a week.

What the late cuts reveal

The workbench cut misses the part of the comparison that matters in a mature wisteria. By stem 45 of a dormant prune, the hardwood is resisting the jaws and earlier sap has begun to stiffen the spring return. At that point, the ARS asks less of the hand.

The tighter nose of the Niwaki still has an advantage in summer when several soft laterals crowd one spur. The broader head that feels easier in winter also takes up more space around retained growth. How much lost precision is acceptable when the tool that tires the hand least has the broader nose?