How to Make a Shotgun Fruiting Chamber

A Shotgun Fruiting Chamber (SGFC) is a simple, low-cost setup used for growing mushrooms. It provides the right humidity and air exchange for mushroom fruiting. Here’s how to build one:

Materials:

  • Large clear plastic storage tote (about 50-60 liters)

  • Perlite (used for moisture)

  • Drill with 1/4-inch drill bit

  • Spray bottle (for misting)

  • Mushroom cakes or trays (e.g., PF Tek cakes)

  • Rack or shelf for inside the chamber (optional)

Steps:

  • Prepare the Container:

    • Choose a large, transparent plastic tote with a lid. The chamber needs to let in light for mushrooms to grow.

    • Drill 1/4-inch holes on all six sides (including the bottom and lid). Space the holes about 2 inches apart, creating a grid pattern. These holes allow for air exchange.

  • Prepare the Perlite:

    • Soak perlite in water. Drain it so that it's wet but not soaking. Perlite will provide the necessary humidity for your mushrooms to grow.

    • Spread about 4-5 inches of wet perlite evenly on the bottom of the tote.

  • Place a Rack or Shelf (optional):

    • If you want better airflow around your mushroom cakes or trays, place a small wire rack or shelf inside the chamber, above the perlite layer.

  • Place Mushroom Cakes:

    • Place your fully colonized mushroom cakes (from the PF Tek method or other substrates) on the perlite or on the rack, leaving space between them for airflow.

  • Maintain Humidity:

    • Mist the inside of the chamber (not directly on the cakes) with a spray bottle 2-4 times daily to maintain high humidity levels (85%-95%). Be careful not to overwater the perlite.

  • Fan for Air Exchange:

    • Fan the chamber by removing the lid and gently waving a piece of cardboard or the lid itself to encourage fresh air exchange. Do this 2-3 times daily to provide oxygen and encourage fruiting.

  • Provide Indirect Light:

    • Place the SGFC in an area with indirect light or use a small daylight spectrum lamp. Mushrooms need light to grow, but not direct sunlight.

  • Monitor and Harvest:

    • Keep an eye on the humidity, misting and fanning as needed. Within a week or so, mushrooms should start to form, and you'll be able to harvest them once mature.

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