Substrate Basics

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Common Substrate Preparation Methods

  1. Pasteurization (60-80°C / 140-176°F)
    • Used for bulk substrates (straw, manure, coir).
    • Preserves beneficial microbes while killing contaminants.
    • Methods:
      • Hot Water Bath – Submerge substrate in hot water for 1-2 hours.
      • Steam Pasteurization – Steam the substrate in a container for 90-120 minutes.
      • Lime Bath – Soak in high-pH water (hydrated lime) for 12-24 hours.
  2. Sterilization (121°C / 250°F, 15 PSI)
    • Used for nutrient-rich substrates (grain, supplemented sawdust).
    • Kills all microbes, requiring a clean inoculation process.
    • Typically done in a pressure cooker or autoclave.
  3. Fermentation/Cold Pasteurization
    • Used for straw or hardwood.
    • Submerge in anaerobic (oxygen-free) water for 4-7 days.
    • Prevents contaminants by allowing beneficial bacteria to colonize.

Popular Mushroom Substrate Recipes

Grain Spawn (Used for inoculation)

  1. Classic Rye Berry Tek
    • Rye berries, gypsum, and water.
    • Hydrate, drain, and pressure sterilize at 15 PSI for 90 minutes.
    • Used for many gourmet and medicinal mushrooms.
  2. Brown Rice Flour (BRF) & Vermiculite (PF-Tek)
    • 1 part brown rice flour, 2 parts vermiculite, 1 part water.
    • Mixed and sterilized in jars with dry vermiculite on top.
    • Great for beginners, commonly used for Psilocybe cubensis.
  3. Millet or Sorghum Spawn
    • Lighter, smaller grains ideal for quick colonization.
    • Hydrate, sterilize, and inoculate with liquid culture.

Bulk Fruiting Substrates

  1. Coir and Vermiculite Mix (“CVG”)
    • 650g coco coir, 2 quarts vermiculite, 4-5 quarts water.
    • Pasteurized, holds moisture well, and resists contamination.
    • Ideal for cube cultivation and low-maintenance species.
  2. Hardwood Sawdust + Bran (For Wood Lovers)
    • 5 parts sawdust, 1 part wheat or rice bran, 1 part gypsum.
    • Sterilized and used for gourmet species like Lion’s Mane, Shiitake, and Oyster mushrooms.
  3. Straw + Manure (For High-Nutrient Species)
    • 50% straw, 50% aged horse/cow manure (hydrated).
    • Pasteurized and often mixed with gypsum or vermiculite.
    • Preferred by Agaricus species and some medicinal mushrooms.

Specialty Substrates

  1. Master’s Mix (Oysters & Lion’s Mane)
    • 50% hardwood fuel pellets, 50% soybean hulls.
    • High in nitrogen, sterilized for commercial production.
  2. Coffee Grounds & Coir (Urban Growing)
    • 50% used coffee grounds, 50% coco coir.
    • Pasteurized, good for Oysters but prone to contamination.
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