Fruit-in-the-Bag Tek: A Step-by-Step Guide

By: Tickle

Fruit-in-the-Bag Tek: A Step-by-Step Guide

During a summer of cultivation, I faced a significant challenge with fungus gnats. The limited growing space compounded the issue, leading to contamination in several totes. After losing multiple batches, I decided to develop a solution: my own version of the “fruit-in-the-bag” tek.

This method involves combining a colonized grain bag with a pasteurized substrate bag, mixing the contents, and leaving the mixture until primordia (initial mushroom formations) begin to emerge. Here’s how you can replicate this process:

Materials Needed:

• Colonized grain bags (e.g., 3 lb bags)
• Pasteurized substrate bags (e.g., 3 lb CVG bags)
• Nitrile gloves
• Alcohol wipes
• A clean work area
• Optional: rubber bands

Step-by-Step Instructions:

1. Prepare the Spawn and Substrate
   • Use a spawn-to-substrate ratio of 1:3. For example, one 3 lb grain bag can inoculate three 3 lb substrate bags.
   • Ensure your workspace is clean and sanitized to minimize contamination risk.
2. Combine and Mix
   • Open the pasteurized substrate bag and the colonized grain bag.
   • Add the colonized grain to the substrate bag.
   • Thoroughly mix the contents by kneading the bag to ensure even distribution.
3. Colonization Period
   • Seal the bag and place it in a warm, dark area.
   • Allow 3-4 weeks for the mixture to fully colonize, depending on the species. Once colonized, the mixture will form a solid mass known as the “cake.”
4. Signs of Pinning
   • Look for the top surface of the cake to begin “sweating” slightly. This indicates that primordia or pinheads are starting to develop.
5. Increase Fresh Air Exchange (FAE)
   • Once pinning begins, use a clean blade to cut a 2-3″ slit in the bag just below the filter patch.
   • Optionally, wrap a rubber band around the bag about 1 inch below the surface level of the cake. This can help prevent side-pinning and mimic the natural pressure of soil.
6. Fruiting Stage
   • After increasing FAE, mushrooms will begin to grow rapidly.
7. Rehydrating the Cake for Further Flushes
   • To rehydrate a moisture-lacking cake and promote further flushes, one of three options can be used:
     1. Misting the cake and inside the bag during harvesting times is the simplest and least damaging to the cake.
     2. Sterilize water by boiling or autoclaving. Using a sterile hypodermic needle and syringe, inject water into areas all over the cake.
     3. Soak the cake in clean water. Use a clean weight to submerge the cake for 1-2 hours. If soaking the cake, do not replace it inside the bag; instead, move it to a tote sitting on a hydrated perlite layer.
8. Harvesting
   • Harvest when the caps have opened, and the veils have split.
   • To remove the mushrooms easily, gently roll the sides of the bag upwards, loosening the cake. Hold the bag by the sides, curl your fingers under it, and carefully slide the bag down until the cake is nearly out.
   • Place the cake on a clean surface, still resting on the bag, and harvest the mushrooms.
   • Slide the cake back into the bag when finished.

Tips for Success:

• Maintain proper hygiene throughout the process to avoid contamination.
• Monitor humidity and temperature levels to optimize growth conditions.
• Experiment with different species and substrate blends to find what works best for your setup.

By following this guide, you can create a simple and effective way to cultivate mushrooms while minimizing contamination risks. Happy growing!