Brown Rice Flour and Vermiculite Cakes

This is a technique for growing many different species of medicinal and gourmet mushrooms indoors relatively quickly. The porus structure of the vermiculite provides the surface area for the fungal growth with the coating of the nutrient rich brown rice flour. You are creating a molded form in the jar, the “cake”, and then “birthing” this cake in order to initiate fruiting. It is important then to use a jar, or other suitable container, with a wide opening for the cake to slide out. These jars as used by the jam manufacturer Bonne Mamam are ideal. Below the ingredients are listed in parts as well as the quantity for 1 of these type of jars.


  • 2 parts vermiculite
  • 1 part BRF
  • 1 part water
  • tinfoil
  • micropore tape
  • spore syringe


  • wide mouthed jars, lids with filter
  • pressure cooker


  • mix vermiculite and BRF
  • add water mix loosely
  • Put into jars, keep loose and airy, up to just below lip of jar (1cm)
  • clean lip of jar with paper towel
  • add dry vermiculite to top 1cm
  • sterilise 15 psi 1hr 30mins
  • leave to cool for 6 – 9 hrs
  • inoculate with spore syringe


  1. Mix the BRF and vermiculite in a large bowl then slowly mix in the water. You are looking for a crumbly loose texture.
  2. Add to the jars without patting it down keeping it loose and airy. Bare in mind what kind of substrate structure you are aiming for.
  3. Fill the jar leaving a 1cm gap below the lip then add a layer of dry vermiculite.
  4. Using and lid with two holes on either side cover the holes with microporus tape. Cover the lid with tinfoil.
  5. Place jars in the pressure cooker and cook at 15 psi for 1hr 30mins.
  6. Once cooled inoculate with a spore syringe. Inject .5ml of the liquid in each hole down the inside of the jar. Cover again with microporus tape.
  7. Leave to incubate for 3-4 weeks
  8. Now birth the cake by slamming the open jar on a flat surface. Wash the vermiculite off and leave to soak in water for 12 hours.
  9. Now rinse the cakes under a tap and roll them in some vermiculite. Place them in your growing chamber and spray lightly with water. Check growing parameter for the species and wait for them to start fruiting.


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