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.