Preparing Mushroom Cane Mulch Substrate

These steps are conveniently completed in an old-fashioned double laundry sink.


20-liter bucket of fine sugar cane mulch (~800g)
2 cups bran (~150g)
1/2 cup hydrated lime

Add cane mulch to a clean 20L bucket. Add bran to the bucket. Fill the bucket with warm water. Press on the substrate to release air bubbles and gently agitate. Wearing gloves and protective eye wear, add 1/2 of hydrated lime and mix until the substrate is thoroughly wet. Let sit for 5 minutes.



•Hydrated substrate
•Esky (cooler) – midsized – 52 x 32 x 29cm or so.
•Old low-quality pillowcase
•Weight (bricks or other)

Lay the pillowcase inside the Esky and fill with handfuls of hydrated substrate.

Tie the pillowcase securely with a long strong rope. Drape the excess rope outside the cooler. The exterior rope allows safe handling of the hot pillowcase later.
Place three bricks on top of the pillowcase.

Boil a kettle full of water and pour over the pillowcase. Repeat until the pillowcase is entirely submerged. Be sure to replace the lid after each kettle full to retain heat. Four to five full kettles of water are usually required.

The pillowcase will release bubbles and may inflate. Pressing down on the bricks speeds the release of air from the pillowcase.

The temperature in the bath should be about 150 ºF (65ºC). Check with a thermometer. Add additional hot water if the bath is too cool. Replace the lid and let sit for 1 hour.


After 1 hour, with gloved hands, remove the pillowcase from the Esky using the rope. Allow to drip into the sink, then place the case on top of the Esky lid.

Place a stove rack over the Esky. Transfer the pillowcase to the stove rack and allow to drain and cool.

When cool enough to handle (10-15 minutes) squeeze the bottom of the pillowcase (with gloved hands) to express excess water.

A high quality, high thread counts pillowcase will impede water drainage. So dedicate an unwanted, low quality, poly/cotton case to mushroom substrate preparation.

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