Cedar wood for miso, easy DIY

Cedar Wood "Weight" for Miso making

🇦🇹 In German

You cannot buy cedar slices for fermenting, you can easily make them yourself

In Japan, cedar wood is used in various production steps when fermenting miso. Koji, for example, is grown in cedar wood boxes (koji buta). Miso, like soy sauce (shoyu), is aged in cedar wood barrels. Miso or shoyu produced in this way is considered particularly noble, and connoisseurs swear by its distinct flavor. Dagmar Maas, a german food journalist, writes in an article: “Miso requires both time and cedar wood.” The newspaper “The Japan Times” even refers to cedar wood barrels (kioke) as “the secret ingredient of soy sauce“. Read the hole article here: Kioke: The Secret Ingredient of Soy Sauce.

Why cedar wood?

You don’t have to do much research to discover why cedar wood is an excellent material for storing miso. Or, in this case, just use a slice of it as a miso cover. Well described, for example, in the post Why Cedar Trees Are Resistant To Bacteria: “Cedar wood is an antimicrobial, meaning it is effective in killing or inhibiting the growth of microorganisms. This makes it an ideal material for a variety of applications, including food storage, healthcare, and personal care. Cedar wood is also naturally resistant to rot and decay, making it a durable choice for long-term use.” This clearly makes it ideal for preventing mold or “Kahmyeast”.

Cedar wood: a secret hack since ancient times!

By the way: putting cedar in the closet or food as protection against moths has been a classic since ancient times. Another practical reason to make barrels out of cedar was certainly that it is very rot resistant, and the wood moves less than many other woods under the humidity fluctuations between use and storage.
There are also historical reasons: Cedar is widely used in Japan, and in the past, almost every wooden tool in Japan was made from cedar because of its good wood properties.

Other types of wood?

In my research, I have not yet discovered another wood with the same qualities. I’m not a wood expert, though. If you know any other wood with these properties that are so perfect for fermenting, please post it in the comments. 🙂

DIY part: Where can I find cedar wood?

Cedar wood is also very popular for BBQ. For this purpose cedar boards are soaked in water for a few hours. Then it’s used as a smoke flavoring or even as a base for fish. Good for us fermenters cedar boards are stock of barbecue stores (for example in hardware stores). Just ask for: Cedar BBQ Planks, Grilling Planks, Grilling Planks for Salmon…

  • Cedar board
  • Glass in which to put the miso
  • Cardboard
  • Ruler
  • Compass (drawing tool)
  • Scissors
  • Pencil
  • Saw, preferably a fretsaw
  • Sandpaper
Craft instructions:

Image 1: Turn the glass over and use a ruler to determine the diameter of the glass. 12 cm in my case.
Image 2: On a cardboard (reused Amazon envelope) draw a circle with 12 cm. Use a compass. Pierce the circle once in the middle. We need the hole later as a marker.
Image 3: Cut out the circle.
Image 4: Put the cardboard slice into the glass to test it. Then you can see right away if it fits or if you have to adjust the dimensions.
Image 5: Place the cardboard disc on the wood and mark it. I left the cedar boards in the packaging, so I could make the mark on the plastic. But this it not necessary. You can also do it directly on the wood if you like.
Image 6: I had 2 boards in the package. I fixed the wood with an adhesive tape, so I could saw out 2 (resp.4) slices right away.
Image 7: Sawing out the circle. I only had a jigsaw at home. With a scroll saw, the circle will probably be nicer than mine. 😉
Image 8: Place the cardboard disc on the sawed out wooden disc and mark the center.
Image 9: With the help of the ruler, draw a line through the center. We now have to saw the wooden disc apart in the middle, because it has to fit through the opening in the glass.
Image 10 & 11: Test whether the wooden disc now fits through the glass opening. If not, saw the wooden disc into 4 pieces.
Image 12: Sand all edges and borders well.

Cat Chief Inspector Schmendrick makes sure I follow all the instructions!


The homemade cedar wood slices can be used repeatedly. Remember to water the miso before placing the wooden disc on top of it! About one to two hours. Otherwise, the wood will absorb the precious miso (tamari sauce) liquid.

Cedar wood slices can be used for:


Don’t forget these cedar wood slices are not used as weights, but as a safety layer over the salted miso. Above that, you absolutely need weights for homemade miso. Preferably ceramic weights. If you don’t have them, you can also fill a jar (that fits in the miso jar) with water and place it on the cedar boards.

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