Substrate for Mycology: A Comprehensive Guide on Straw

PROCEDURE:

Preparation of Straw:

• Begin by taking bundles of straw and, using gardening shears or a sharp knife, cut them into smaller pieces.
• Aim for lengths between 2-4 inches. These smaller sizes allow the mycelium to colonize the substrate more efficiently.

Incorporating Gypsum:

• If you decide to incorporate Gypsum, spread your chopped straw out on a flat surface. Sprinkle the Gypsum evenly over the straw, ensuring a thorough mix.
• This addition provides the straw with improved structure and moderates the pH level to create an ideal environment for mycelium growth.

Soaking Process:

• Transfer the straw (and gypsum mixture, if used) to a large pot or container.
• Fill it with enough water to submerge the straw completely. Allow it to soak for a full 24-hours. This soaking period ensures that the straw is fully saturated, making it a receptive substrate for colonization.

Draining Excess Water:

• Once soaked, place the straw in a colander or a mesh bag, allowing water to drain off.
• It’s crucial to ensure that the straw is moist but not dripping wet, as overly wet substrates can lead to contamination.

Adding Karo Syrup:

• If you opt to use Karo syrup, pour the designated amount over the damp straw.
• Mix thoroughly, ensuring even distribution. This carbohydrate-rich syrup serves as an additional food source for the mycelium, boosting its growth.

Jar Packing:

• Filling: Load the jars with the Straw mixture with the correct amount of Straw (See Recipe).
• PLEASE NOTE: Ensure you leave about a 1-inch gap at the top to facilitate room, ensuring there’s enough headspace for air exchange and to prevent jar overflow as mycelium grows.
• Securing Lids: When placing the lid, ensure the rubber seal faces upward. This helps prevent the jars from getting vacuum-sealed during the sterilization process. Another option is to use a mycology lid such as one that contains a filtered vent and/or injection port (we have articles, DIY Supplies, and both Free & Paid for Mycology Courses hosted on our 🍄 Mushroom Academy!
• Foil Cover: Wrap the tops of the jars with aluminum foil. This provides an added layer of protection against potential moisture intrusion during pressure cooking.

Sterilization:

• Using a pressure cooker, place a cloth or metallic stand at the base to prevent the glass jars from direct contact with the cooker’s bottom.
• Arrange the packed jars inside. Set the pressure cooker to 15 PSI and let it run for 90 minutes. This step is crucial to kill off any potential contaminants.

Cooling Phase:

• After the sterilization process, turn off the heat and allow the pressure cooker to cool down naturally.
• Once it reaches room temperature, the jars can be safely removed and are ready for inoculation.