How do I sharpen a spade, hoe or axe?

Almost nobody sharpens a spade, and it makes more difference than any other five minutes spent on garden tools. A sharp spade slices through roots and cuts a clean edge into turf instead of tearing; a sharp hoe severs weeds at the root rather than dragging them. These edges need to survive stones and grit, so they are ground steeper and finished coarser than any woodworking edge.

Safety

What you'll need

• Mill file, 200–250mm, with a handle
• Wire brush
• Vice or clamps
• Gloves and eye protection
• Medium sharpening stone or a file card (optional)
• Light oil

Step by step

1. Clean the tool first.Wire-brush the soil and rust off the blade so you can see the existing bevel. A file skids off dried mud and is ruined by grit.
2. Clamp it securely.A spade in a vice by the shaft, or braced against a bench with the blade supported. It must not move while you file — a slipping file is how people cut their hands.
3. Identify the existing bevel and follow it.Most spades and hoes have a bevel on the front face — the face you look at as you dig — and a flat back. Follow the existing angle rather than inventing one. On an axe, the bevel is on both sides and it is curved, not flat.
4. For a spade or hoe, file the front face only.Work the file across the bevel in one direction — a file cuts on the push stroke only, so lift it on the return. Aim for around 30 to 45 degrees: steeper than a chisel because it must survive stones. Work along the whole edge evenly, following the curve of the blade.
5. Feel for the burr and remove it.When a burr appears along the back edge, that face is done. Take it off with a single light pass of the file flat on the back, or a couple of strokes with a stone. Do not file a second bevel on the back of a spade.
6. For an axe, keep the convex profile.An axe edge is deliberately curved in section — a wedge would jam and would chip. Work a file or a coarse stone in small circles along the edge on both sides, following the existing curve. Take equal metal from both sides so the edge stays central.
7. Finish an axe with a stone.A round or oval axe stone, or a medium then fine flat stone, worked in circles along the bevel on each side, gives a working edge that will cut paper but is not razor-fine. An axe polished like a chisel chips on the first knot.
8. Do not overheat with a powered grinder.An angle grinder or bench grinder removes metal fast and burns the edge faster. If you must use one for badly damaged tools, use a light touch and dip in water constantly. Blue steel is soft steel and it must be ground away.
9. Oil the blade.Wipe the whole head with a light oil. Garden steel rusts within days, and rust pits an edge you have just filed.
10. Sharpen the other garden tools while the file is out.Hoes, edging irons, mattocks and turf cutters all take the same one-sided treatment. Lawn mower blades, secateurs and shears each have their own bevel geometry and are covered separately.

Tips

• An edging iron or a half-moon turf cutter benefits from sharpening more obviously than anything else in the shed.
• A file needs a handle. A bare file tang driven into a palm is a classic and entirely avoidable injury.
• Stainless steel garden tools file harder than carbon steel and hold an edge less well, but they will not rust while they wait for you.
• Do not sharpen the sides of a spade blade into a point unless you want an edge that will happily cut through a cable — keep the sharpening to the leading edge.

Keeping on top of it

• Clean soil off blades and dry them (After every use)
• Touch up a spade or hoe edge with a file (Every few sessions of heavy use)
• Oil bare steel (Before storage and at the end of the season)
• Check and tighten axe and spade handles (Start of each season)
• Full sharpen and rust removal (Annually)

Questions people ask