Tom Harris: Sharpening Garden Tools

A guy wrote and asked about cleaning, lubricating and sharpening gardening tools like shovels, hoes, pruning shears, etc.

There are lots of books written on this subject and I’ve actually read a few of them. So, it’s kinda hard to tell you how to do this in a short note, but here goes.

Before sharpening any gardening tool, it’s important that you remove all the dirt, sand, sap, and general crud from the tools. If it has dirt and/or sand on it, scrape off as much as you can with a putty knife or similar tool and then use the garden hose to wash it off. Let it set in the sun to dry on both sides. If it’s a pair of pruning shears and they have plant sap on them, wash them off with water first and see if that works. If it doesn’t, spray WD40 on the sap and let it set for a few minutes. Then use steel wool to rub the sap off. Be careful, as you’ll be working next to the sharp edge of some of these tools. Also you should know that if you use steel wool, it WILL dull the tool you’re working on if it was sharp when you started.

After you use any gardening tool, it’s a good idea to spray it with WD40 before you put it away. It helps to keep the rust away and lubricates the working joints of the tool. If these tools have wooden handles on them, it’s a good idea once a year to put a coat of boiled linseed oil on them to keep the wood pliable and strong. Just follow the directions on the label. One coat is enough, but two can’t hurt.

To sharpen large tools like shovels, hoes, axes and the like, use a file made for that purpose — usually it’ll say “garden tool sharpener” on the handle. If you don’t have one of these, use any double-cut file and it should do close to the same job.

Look for the side of the tool that had the original sharp edge on it. Your job is to bring this edge back to its original shape and sharpness if you can. Start by PUSHING the file along the former sharp edge (pulling a file won’t do anything except dull the file.) With your first stroke, you should be able to see whether or not you have followed the same angle as was originally put on the tool. If not, adjust your angle on the file to do that. Continue filing until a small burr is produced all along the other side of the sharp edge. Then turn the tool over and place the file flat against the flat surface and, using only ONE STROKE, push the file across the edge. This should remove the burr and leave a sharp edge. If it doesn’t, do it exactly the same way, one more time. At no time should you try to put an angle on the back side — the angle is normally only on one side of the tool.

Rub your thumb or finger ACROSS the sharp edge, not along the edge or you’ll slice the heck outta your finger. If the edge is sharp, you’ll feel it. If it’s not sharp, you’ll fee that, too. Another trick is to hold the sharp edge at an angle to a bright light and sight along the edge. If you see any shiny spots, those are the dull spots and they indicate you’re not finished yet. Just repeat the steps above until the edge is sharp. Spray it with WD40 and hang it up to dry.

Sharpening pruning shears and REALLY sharp tools isn’t quite this simple although the process is exactly the same. First you have a decision to make; i.e., are you gonna take the tool apart or not. If you take it apart, you can remove all the rust and crud more easily; but be sure you know what you’re doing and watch where you lay screws and small parts so that you can get the tool back together again. I’m going to assume that you’re NOT gonna take it apart.

For this job, you’ll need a small sharpening stone to be able to get to the small parts of the blade. Personally I prefer to use the diamond-dust stones; reason being that they stay flat and sharp for a long time and you never have to worry about what to use as a lubricant on the stone (they’re really not stones at all, they’re a piece of plastic with a piece of metal on top with the diamond dust glued to it.) These stones can be used dry or wet. If you use it dry, just be sure to clean it with water when you’re finished each time. If you wanna wet the stone, you can use plain old water or something like WD 40 if you’d like. If you use another type of real-stone stone, be sure to use the type of lubricant you’re supposed to use for that particular stone. Usually something like kerosene or paint thinner will do the job. The main thing is to keep the stone from filling up with metal particles — you can see them on the stone. To do this you have to keep the stone wet all the time.

As I said, the process is the same. Rub the stone so that you’re pushing the stone OFF the edge of the blade while trying to find the original angle of the edge. If you’re using a diamond stone, push 4-5 times along the length of the whole blade and/or until you feel the burr on the other side of the blade. Lay the stone flat on the back side and push one time and the burr will be gone. Then the blade should be sharp; if not, repeat the process.

If you have the type of shears where the blade is sharpened on both sides, sharpen one side until you feel the burr on the other side, then sharpen the other side until you feel the burr again. Use a finer-grit stone to remove the burr with just one or two light strokes.

Be sure to coat the newly sharpened blade with WD 40 before you put it away.

If you have any questions, write me at and I’ll get right back to ya. Good luck.