How to Sharpen Garden Tools for Best Performance

One of the important things I learned from my father is to always keep a sharp edge on shovels, hoes, and other garden tools used for cutting. Indeed, working with a dull hoe amounts to pounding weeds rather than slicing through them, and a blunt spade will stop at roots and other obstructions, whereas a sharp one will cut right through them. Every gardener needs to know how to restore sharp edges, a procedure I repeat often during the peak weeding season of late spring.

As you can tell from the photographs here, I am not a tool perfectionist. My garden tools often stay out in the weather, and I’ve had most of them for 20 years. But I do keep my two mill files (used for sharpening) indoors, amidst my gardening gloves, because they rust easily. Also called flat files or draw files, mill files cost only a few dollars, and all hardware stores sell them.

A mill file rasps away metal in the same manner that sandpaper shaves down wood. Tiny shards of metal are released as the mill file tears them off. Always work outdoors and keep your work low, a safe distance from your face, to keep shards away from your eyes and breathing space.

Making a Sharp Beveled Edge

The angle of a blade’s sharp edge is called a bevel. In general, your tool’s slicing action will be accompanied by a gentle upward lift if you make a deep bevel on the back side of the blade, and a narrower one on the front. This approach is fine for spades and most hoes, but stirrup hoes and others designed to be pushed and pulled horizontally need an even bevel, with all edges equal in the angle at which they come to a point.

Sitting down with a medium-grade mill file, I begin any sharpening job by roughing out gouges and dings caused by digging into rocks and ice. For this, it’s fine to saw back and forth with the file, because you’re shaping rather than sharpening. When the edge is smooth, I change my strokes so that they move outward at a diagonal angle, across the edge I’m sharpening. This practice is called "draw filing" because you draw the file outward and off the edge over and over again. It takes me about five minutes to restore a sharp edge to a neglected spade, but less than half that time to touch up a blade I’ve sharpened in recent weeks.

Most garden tools that came with a sharp edge should be re-sharpened at least once a year – or once a week when they’re being jammed into soil hundreds of times a day. With high-efficiency tools that shave down weeds like the Cobrahead (at right) and the diamond hoe (which has four cutting edges), sharpness makes such a huge difference that you might want to carry a small file in your back pocket during long weeding sessions.

Children’s gardening tools are dull for safety reasons, and sharp-edged garden tools should be stored where kids can’t reach them. Or, cut a piece of old garden hose the same length as the blade, slit it down the side, and pop it over the blade as a safety cover.

By Barbara Pleasant