Freshly sharpened equipment helps give gardeners a cutting edge

With a flurry of yard and garden work well under way, our garden gear – hoes, spades, pruners and rakes – keeps us moving from task to task safely and swiftly. Most garden tools have a cutting edge that helps penetrate soil or plant tissue, and all these working surfaces require our special attention during the height of the gardening season.

A fine gardening tool is truly a thing of beauty. The handle of your favorite trowel slides perfectly between your palm and fingers while you transplant. You and your hoe make the perfect cultivating machine as you tear through offensive weeds. Your spade glides through rugged sod as you claim more ground for a new garden bed. Yet, the function of any of these tools can be seriously compromised if care of its cutting surface is neglected over time.

Some tools do fine with a serious sharpening just once during the gardening season; others require more frequent attention. A well-sharpened blade not only makes your work easier, it is healthier for the plants with which you work. Poorly tended cutting blades tear or damage stems, roots and branches. A dull lawn-mower blade, for example, rips grass with its spinning action, rather than slicing through the grass leaves. A dull hand pruner crushes stems rather than slices them. Crushed or bruised plant tissue invites disease. Properly tended tools make a “clean” cut and create a wound, which the plant can more easily mend.

There really is nothing mystical about sharpening tools, although fear of doing it improperly has probably prevented many gardeners from undertaking the task. It’s important to understand that all cutting edges, whether on an ax or hoe or shearing tool, are basically wedges. The wedge has two faces that come together at a point. The angle between the two faces is called the edge bevel. A maul has a wide edge bevel with a huge mass of metal behind it to provide weight to cut through tough wood. A grafting knife, on the other hand, has a fine, narrow edge bevel that provides a smooth slicing action through delicate stems.

New tools have an edge bevel appropriate for the tasks for which they are designed. When sharpening tools, gardeners should strive to duplicate the original edge bevel. Using tools may wear the cutting edge unevenly, so this task may be difficult. Many tools require a “rough” sharpening with a grinder attachment on a power drill and follow-up with a sharpening stone lubricated with honing oil. As a general rule, you should attempt to sharpen the blade, mimicking the original edge bevel, while removing as little metal from the blade as possible.

Lawn mower blades may require sharpening after each use, first with a power drill and then with a sharpening stone. Count the number of passes you make over one side of the blade and duplicate that number on the other side of the blade to keep the blade balanced. Hand shears and pruners should be sharpened with a flat file or a sharpening stone. Remove the pivot bolt where the blades are affixed and set the blade in a vise while you sharpen the cutting edge with careful strokes of the sharpening stone.

Grafting or cut-flower knives should be sharpened by passing the knife blade over a lubricated sharpening stone with the cutting edge trailing through each stroke. Pass the blade over the stone in one direction, then flip the blade and move in the opposite direction, maintaining the blade at about a 15 degree angle to the stone.

Spades and hoes should be sharpened at about a 50 degree angle with short, even strokes of the flat file. Rest spades on a bench with the concave face up while you file. Place hoes in a vise and sharpen the outside face of the blade.

Whether using a power grinder for rough sharpening work or a sharpening stone for finer work, flying metal can easily lodge in the eye or skin, so please remember to wear safety goggles and gloves when sharpening tools. To avoid accidental starting, always remember to remove the spark plug from your lawn mower or to unplug power equipment before sharpening the blades.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, RR1, Box 2120, Montville 04941, or e-mail them to dianagc@midcoast.com. Selected questions will be answered in future columns. Include name, address and telephone number.