• Grain medium is mostly used for spawn production. Prepared in jars or bags, and sterilized before being inoculated and incubated. Possible grains include kernels, berry, oat and flour of : Rye, Rice, Wheat, Millet, Maize, Quinoa, Amaranth, Buckwheat, Sorghum, Oat, Barley, Spelt, Linseed, etc.


  • This steps prepare the grains jars :
    1. First thing is to put grains in each quart jar, according to formula. Be sure to leave room in the jars to shake the grain (fill only to third).
    2. Add the right amount of water for the soaking according to formula
    3. Let it soak for 12-24 hrs. Avoid soaking more than 16 hrs as grains may germinate. (Or you can soaking it with hot water to kill the grain).
    4. Shake or mix the content after soaking.
    5. Place the lids over the jars and make one to four holes in the jar lids.
    6. Close the holes with a filtering medium, such as Tyvek or breathable tape.
    7. Your jars are ready for pressure heat sterilization.

Alternative preparation : RR method

5 steps to perfect grain spawn,
from "Let's grow mushrooms" DVD, by RR

  • Another method of grain preparation, known as RR method (see video at the right), allow to get kernels of grain with perfect texture, with no stickness, clamping or dirt, minimizing contaminants and helping for shaking the spawn, although it may leach more nutrient away than classic method. The steps for this method are :
    1. Rinse the grains with hot water, repeat until the water gets clean.
    2. Soak 12h to 24h, with 1 tablespoon of gypsum for each kg
    3. Boil for 10 minutes, drain well and shake well to evaporate steam. At the right moisture, a spoon of grain left 15 seconds left on toilet paper will not leave moist spots
    4. Load jars 2/3 full
    5. Close your jars with prepared lids. RR prepares lids by placing a filter disk and mounting the metallic center upside down. If you use different type of lids, you can prepare lids by making a hole and covering it with a filtering medium, such as Tyvek or breathable tape, and place an aluminium foil with few holes under the cover to protect the filter from touching the grains when you shake
    6. Cover the jars with aluminium foil
    7. Your jars are ready for pressure heat sterilization, 90 minutes at 15 psi


  • Pure Grains Formula

    • Rye,
      • (1/2 liter or 16 oz jar, 60% moisture )
      • 100 gram Rye grain (125 ml.)
      • 150 ml water
      • 0.5 gram gypsum
      • (1 liter or quart jar, 50% moisture )
      • 200 gram Rye grain (250 ml.)
      • 200 ml water
      • 1 gram gypsum (1/3 teaspoon)

    • Wheat, similar to Rye but very easy to clamp
      • 250 ml of wheat grain
      • 175 ml water
      • 1-2 gram gypsum, prevent from clamping
      • 100 ml of Vemiculite (Optional), prevent from clamping

    • Other grains : Millet, Maize, Quinoa, Amaranth, Buckwheat, Sorghum, Oat, Barley, Spelt, Linseed, etc.

  • Meal Formula (e.g. oat)
    • Oatmeal works fine as a brf substitute. Use the same ratio of crumbled up oatmeal, vermiculite and water according to PF's tek:
    • 30 - 40 ml of meal, instead of brown rice powder ( 1/8 cup or 15 gr )
    • 125 - 180 ml of vermiculite (medium size) ( 1/2 - 2/3 cup or 12 - 18 gr )
    • 40-45 ml (cc) of water (a little less than 1/4 cup, or 1,5 ounces, or 3 tablespoons and 1 teaspoon)
    • Maximum fruiting formula (60 ml of meal, 125 ml of vermiculite, 60 ml water)

  • Mixes Formula

    • Wheat Millet Flax Substrate
        • 2c organic hard red wheat berries
        • 2c Vermiculite
        • 1/3c organic millet
        • 1/4c flax meal
        • 4c water
      1. cook wheat in water until berries are soft.
      2. drain off excess water from wheat, reserving 1c.
      3. grind millet in coffee grinder.
      4. mix millet and flax with vermiculite.
      5. add wheat and reserved water.
      6. mix well.
      7. sterilize @ 15psi for no less than 30 minutes.


  1. Stamets
  2. http://www.shroomery.org/forums/showflat.php/Number/12813941
  3. http://www.shroomery.org/forums/showflat.php/Number/462697
  4. http://mycotopia.net/archives/discus/messages/5/3358.html?1004554748
  5. https://mycotopia.net/forums/fungi-magic-mushrooms/10865-oatmeal-substrate.html
  6. http://www.shroomery.org/8432/From-syringe-to-print-using-rye
  7. http://www.youtube.com/watch?v=dSVK00CYpZw