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MycologyLog Build Sheet
Layered Grain + Fruiting Block

Grain + Yeast-Conditioned Fruiting Block Layered Hydration & Sterilization Build

A simple layered build: hydrated grain on the bottom, yeast-conditioned sawdust substrate on top, then sterilization and LC inoculation into the grain layer.

🌾 Grain 🪵 OSD 🥣 Oats 🍞 Yeast 🔥 Sterilization 💉 LC Injection
🌾

Grain Portion

Hydration Trial (Bottom Layer)

~45% Moisture
Ingredients
  • 12 oz grain
  • ½ tsp sugar
  • 25 oz water
Hydration Level: 10 oz water ÷ 22 oz total = ≈ 45% moisture
Ideal for grain spawn—loose, hydrated kernels with no surface water.
Instructions
  1. Combine grain, sugar, and water in a pot.
  2. Heat to 221°F for 30 minutes.
  3. Drain thoroughly.
  4. Bag and weigh:
    • Final net weight: 22 oz
    • Water absorbed: 10 oz
  5. Spread as the bottom layer in an 8×4×14 grow bag.
🪵

Fruiting Block

Yeast-Conditioned Substrate (Top Layer)

~45% Moisture (Est.)
Ingredients
  • Water
    • 1 full quart jar (to the rim)
    • + 8 oz additional water
  • Dry materials
    • 1 full quart jar OSD (oak sawdust)
    • 4 oz oats (volume)
  • Supplements
    • ½ tsp sugar
    • ¼ tsp yeast
  • Total wet weight: 89 oz
Estimated Hydration: 40 oz water ÷ 89 oz total = ≈ 45% moisture
Based on total water added vs. final substrate mass.
Instructions
  1. Heat water to 98°F.
  2. Add sugar and yeast; activate for 10 minutes.
  3. Add OSD and allow 10 minutes for absorption.
  4. Add oats and mix thoroughly.
  5. Layer substrate on top of the grain layer in the grow bag.
  6. Allow to stand unsealed at ~72°F for 24 hours to allow yeast bloom.

Pre-fermentation produces CO₂, B-vitamins, amino acids, and heat-stable compounds beneficial to mycelial growth.

🔥

Sterilization & Inoculation

Sterilization
  1. Prepare bag for sterilization.
  2. Sterilize for 120 minutes.
  3. Allow to cool fully.
Inoculation
  1. Attach a self-healing injection port near the bottom.
  2. Inject 20 mL liquid culture into the grain layer.
  3. Apply tape over the port to ensure adhesion.
Build intent: Separate hydration profiles for grain vs sawdust while allowing yeast-conditioned nutrients to remain in the top layer after sterilization.
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