Hori Hori Gardening Knife

Edge Angle

I have never had so many good ideas day after day as when I worked in the garden. John Erskine

The Japanese Hori Hori Gardening Knives, also known as Soil Knives, are used in the garden for many activities, including digging, cutting, weeding, & planting. ("Hori hori" means "to dig" in Japanese.)

Guidelines shown below are for Included Angles (α). The two edges could be sharpened differently, but that is not typically done.

If one side has a serrated edge, and you wish to keep it that way, consult the page on Serrated Edge Kitchen Knives.

There can be a debate about how sharp the hori hori knife should be. Notes regarding this are below in the Notes & Comments section.

General Guidelines
α	Micro bevel	Notes
20°	+5°	Gut Hook The inside edge will need to be deburred using a machinist's hand file or a sharpening stone. The use of a micro/secondary bevel makes the re-sharpening easier and faster, particularly if done in the field. Note: Some blades have a hooked blade used for cutting twine. This is similar to a hunting knive's gut hook used splitting the skin on a game animal when butchering in the field. Sharpening this concave edge requires a round slip stone or sandpaper wrapped around a dowel rod.

Notes & Comments

Information regarding Grindstones

How Sharp Should a Hori Hori Knife Be?

The gardener needs to decide how sharp the hori hori knife should be based on activities for which the tool will be used. Some of the decision criteria worth considering are outlined below.

Not So Sharp

If the gardener wants to use the hori hori knife for these activities, then making it less sharp is recommended.

• Planting seeds or seedlings into rocky soil: When the gardener is planting seeds or plants into ground which may be rocky or have other debris / artifacts (a pot of gold maybe?), then the hori hori knife's blade will most likely get damaged. Having it too sharp will make this more probable and more easily damaged.
• Hacking away at woody plants: When the gardener is using this tool to hack away at woody plants such as berry canes, a very sharp edge could be damaged. This is not a recommended activity for this tool, but it does happen.

Very Sharp

If the gardener wants to use the hori hori knife for these activities, then making it quite sharp is recommended.

• Propagating plants by division: examples of the plants which are propagated by division include hostas, irises, lilies, and sedum. Having a sharp blade to perform these activities is key to minimizing damage to those plants when splitting them apart.
• Cutting back roots when repotting: Plants which are pot-bond often have roots running in ways the gardener needs to prune back so that the plant can thrive. Many bonsai activities fall in to this category. A sharp blade is needed.
• Pruning back hard: Cutting back plants like switchgrass is certainly easier when using a very sharp tool. And using a sharp blade to do this reduces the effort needed, which should reduce the potential for injuring the gardener.

Cautions: depending on how the gardener uses the tool's sheath for encasing the blade, having a very sharp blade makes it easy for the gardener to:

1. Damage the sheath when putting the tool away. This is a real issue as many sheaths are not heavy duty and easily damaged.
2. Cut themself whilst reaching around to put the tool away.

Morakniv knife

Alternatively, the gardener could use a different tool such as a fixed blade knife like a Morakniv or Bowie knife for these activities.

Tormek Notes

The Tormek SG-250 grindstone works well for sharpening this tool. Also, grinding the outside edge using the Tormek's vertical position (with the grindstone rotating towards the edge) is recommended.

Because the blade is curved, the KS-123 does not work for this application.

Bench & Angle Grinders

Using a bench or angle grinder is not recommended as this will surely overheat the tool, removing the temper from the edge. Additionally, the shaping of the edge is difficult to control.

Sharpening the Edge

KJ-45 Bottom Stop

If using a Tormek with the KJ-45 jig, the bottom stop is recommended (as indicated in the picture to the left). This makes setting the angle far easier.

The picture on the right shows a Japanese weeding sickle being sharpened on a Tormek (the blue piece behind the grinding wheel is a drip tray).

If you choose to use a machinist’s hand file,

1. Start with a 8-10" medium (or second cut) file.
2. Finish with a 6" smooth cut file, then use this file to remove the burr.

Micro Bevel Notes

The micro bevel makes the resharpening of this tool easier. If you sharpen the tool using a machinist's hand file, this is recommended. It is less critical if you use a Tormek grinder for the sharpening.

More Information

Web Sites

• Hori Hori Explained: The Best Japanese Gardening Knife Guide - the BBC's Lee Burkhill explains a lot about these tools, and has some great videos on how to use them.
• Matt Stern at The Tool Merchants
  • Garden Tool Care Master List, outlines the tools which help care for garden tools.
  • How to Care for Wooden Tool Handles, gives some good tips.
  • How to Sharpen Garden Tools, provides a good overview.
  • What are the Best Oils for Garden Tools?, reviews the oils he found best for garden tools.

Videos & Presentations

• Hori Hori Japanese Gardening Knife Guide - The Garden Ninja, Lee Burkhill, shows you how to use a Hori Hori Japanese gardening knife.