Secondary mycelium is made by breaking up your fully cultured primary blocks (usually grown in mushroom bags) and transferring them into bottles or other containers for re-cultivation.
This process is super useful because it gives you the chance to mix in additives like trehalose.
Just like we do with fermented substrates to potentially improve larval growth.
✅ Step-by-step: Re-Culturing Mycelium
1. Disinfect your workspace and tools.
Use ethanol to clean your hands, surfaces, and equipment thoroughly.
Sterility is key.
2. Break up the primary mycelium block
Gently crumble the fully colonized block into smaller pieces.
3. Add any supplements or additives
This is where you can get creative. Many breeders add trehalose, but feel free to experiment.
4. Mix everything together
Moisture content should be just like when preparing fermented substrate.
When you squeeze it in your fist, it should hold shape, but not drip water.
5. Pack the substrate into containers.
Glass jars, plastic bottles all work.
Just make sure there’s proper ventilation through filters.
6. Incubate until the mycelium recolonizes
Store in a dark, temperature controlled space (ideal range: 65–75°F / 18–24°C)
Full recolonization usually takes 2–5 weeks, depending on the container size and how much culture was added.
🔎 Visual Timeline of Cultivation Progress:
Day 5 – Mycelium starts spreading
Day 14 – Most of the surface colonized 
Day 45 – Fully recolonized and ready to use