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How to Grow Mushrooms With Spent Barley

mushrooms image by Warren Rosenberg from

Growing mushrooms indoors may seem like a mysterious practice, but it is rather simple when done with the right materials. Mushrooms require a substrate to grow upon, such as rice, wood or spent barley. The substrate makes a warm, moist, decaying medium ideal for mushroom growth. Mushrooms spores can be purchased from a variety of retailers. Barley is used in the production of beer. Spent barley can be obtained by local microbreweries or home brewers. They're often glad to get rid of the stuff. Once the spores are placed in the slowly decaying barley, the fungi will produce edible mushroom caps. Shitake and oyster mushrooms grow well in spent barley.

Preparing the mix

Fill a bowl with 140 ml of vermiculite, 40 ml of spent barley and slowly pour water into it while stirring with a spoon. Only put in enough water to slightly moisten the mixture.

Fill the half-pint jar with the mixture and top off the jar with a small amount of dry vermiculite.

Place three layers of foil over the top of the jar.


Pour 1 inch of water into the bottom of your pressure cooker and place a rack at the bottom of the cooker.

Place the jar with the mixture in it onto the rack inside the pressure cooker and seal the lid.

Warm the pressure cooker slowly, over a time period of 15 minutes, until the pressure is 15 psi. Leave the jar in the cooker for 45 minutes.

Remove the jar from the cooker and allow to cool for five hours. The high heat from the pressure cooker will have sterilized the spent-barley mixture


Shake the spore syringe to break up the spores inside.

Heat the tip of the syringe with the lighter so that it is glowing. That sterilizes the tip. Allow it to cool before using.

Lift the top two layers of foil off of the jar and stick the syringe through the remaining piece. Slowly inject the spores into the mixture. Replace the foil.

Place the jar in an area that remains between 70 to 81 degrees Fahrenheit. You will see germination inside the jar after three to five days. This germination is the mycelium.

Place the contents of the jar inside of an old fish tank or plastic bucket after the jar has begun showing signs of small pin head mushrooms growing, which should begin between five and 10 days of inoculation. This means the mycelium is ready to fruit. Cover the old fish tank or plastic bucket with a plastic bag to prevent changes in humidity until the mushrooms are ready to harvest.


If the mycelium inside the jars appears any other color than white, then the medium is contaminated and all must be discarded.

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