How do I sharpen secateurs and garden shears?
Why only the outer bevel is sharpened on a bypass pruner, keeping the blade profile rather than flattening it, and the sap and adjustment that cause most poor cutting.
- Difficulty
- beginner
- Time
- 25 min
- Read
- 5 min
- Safety
- caution
Short answer
On bypass secateurs, sharpen only the outer bevel of the cutting blade, following the existing angle, and never file the flat inner face — that face has to stay flat for the two blades to pass each other cleanly. Clean the sap off first; a lot of apparently blunt secateurs are just gummed up.
Bypass secateurs work like scissors: a sharpened blade passes a flat anvil-like counter blade with almost no gap. That geometry, not just the edge, is what cuts. Sharpening the wrong face or removing too much metal opens a gap between the blades and the tool will crush stems no matter how sharp the edge is.
Safety
What you'll need
- A fine diamond file, or a small sharpening stone
- Wire wool or a green scouring pad
- White spirit or a resin cleaner
- Light oil
- A small screwdriver or spanner to dismantle (optional)
Step by step
- Clean the sap off before deciding they are blunt.Dried sap and resin build up on both faces and stop the blades passing cleanly. White spirit or a proprietary resin remover on wire wool takes it off. Many secateurs that seem finished are simply dirty.
- Check the pivot adjustment.There is usually a nut or a screw at the pivot. If the blades have play, they cannot shear past each other and will chew rather than cut. Tighten until there is no side-to-side movement but the tool still opens freely.
- Dismantle them if you can, but photograph it first.Working on a separated blade is far easier and safer. Note the order of the washers, the spring and any bushes — they only go back one way, and the spring is easily lost.
- Identify the cutting blade and its bevel.On bypass secateurs only one blade is sharpened. It has a bevel on the outer face and a flat, or very slightly hollow, inner face. The other blade is the counter blade and is not sharpened.
- Follow the existing bevel angle.Lay the file flat against the bevel and rock it until it sits flush. That is the angle. Secateur bevels are usually quite steep, around 20 to 25 degrees, because they cut by shearing green wood.
- File in one direction, away from the edge.Push strokes from the base of the blade towards the tip, following the curve, with moderate pressure. Six to a dozen strokes is usually enough on a blade that is merely dull.
- Work the full curve of the blade evenly.Do not concentrate on the middle. Secateurs cut with the whole curve and an edge sharpened only in one place cuts only in one place.
- Never file the flat inner face.Removing metal there opens a gap between the two blades, and a gap means the stem gets pushed into it and crushed instead of cut. This is the single mistake that ruins secateurs.
- Remove the burr from the flat face.Lay the flat side down on a fine stone or draw a fine file flat across it once or twice, just enough to take the wire of steel off. Flat means flat — no angle at all.
- Reassemble, adjust and oil.Rebuild in the order you photographed, set the pivot so there is no play, and put a drop of light oil on the pivot and a wipe over the blades.
- Test on a green stem.A clean cut with no crushing at the edges, and the stem should not fold over as the blades close. Torn or crushed cuts on plants invite disease.
- For shears, sharpen both blades the same way.Long-handled shears have a bevel on each blade. Same rules: follow the existing bevel, work the full length, never touch the inner faces, and set the pivot so the blades pass without play.
Tips
- Wipe blades after every use and oil them before putting them away. Sap left on overnight is much harder to remove than sap wiped off wet.
- Sharpen little and often. Ten strokes every few sessions is easier than trying to recover a genuinely blunt tool.
- Replacement blades are available for most good secateurs. A nicked or badly worn blade is often cheaper to replace than to grind back.
Common mistakes
- Filing the flat inner face of a bypass blade — The two blades must pass each other with almost no gap. Any metal taken off the flat face creates a gap, so stems get dragged into it and crushed. Once the geometry is lost it cannot be sharpened back.
- Rounding the bevel by rocking the file — Exactly as with a knife, an inconsistent angle produces a rounded edge that will not cut cleanly. Rest the file flat on the bevel and keep it there for the whole stroke.
If it doesn't work
Stems get crushed rather than cut
Cause: Blades not passing closely — worn pivot or a filed inner face — Fix: Adjust the pivot to remove play; if the inner face has been filed, fit a replacement blade.
Cuts fine at the base, not at the tip
Cause: Uneven sharpening, or blades springing apart at the tip — Fix: Work the whole curve evenly and check the pivot tension.
Sap builds up within a session
Cause: Cutting resinous material — Fix: Clean during the session with a rag and white spirit; a light oil film on the blades slows it down.
Blade has a chip in it
Cause: Cut wire, a nail or a stone — Fix: File back to below the chip if it is small, keeping the profile; a deep chip means a replacement blade.
Tool is stiff to open
Cause: Pivot over-tightened or dry — Fix: Slacken slightly and oil, aiming for no side play but a free action.
Questions people ask
Do anvil secateurs sharpen the same way?
The principle is the same but the geometry is different: an anvil pruner has a single blade closing onto a flat anvil, and the blade is sharpened on both sides to a centred edge. There is no passing gap to preserve, but keeping the anvil face clean and flat matters.
Is it worth sharpening cheap secateurs?
Yes, but expect less from them. Cheap tools often use softer steel that dulls quickly and a pivot that develops play and cannot be adjusted. If the pivot is loose and not adjustable, sharpening will not restore a clean cut.