A shotgun fruiting chamber is a simple and effective setup used in mushroom cultivation. This chamber provides the ideal conditions for the fruiting stage of mushroom growth by creating a high-humidity environment while allowing for proper air exchange. Maintaining both high humidity and fresh air is critical: humidity keeps the mushrooms from drying out, while fresh air prevents the buildup of carbon dioxide, which can inhibit proper development.
Here’s a step-by-step guide on how to make a shotgun fruiting chamber:
Materials you’ll need:
- Plastic storage container with a lid: A clear or translucent container works best, as it allows for light entry.
- Perlite: A lightweight, porous material that retains moisture and provides humidity.
- Drill with a 6mm drill bit: For creating holes in the container.
- Hygrometer (optional): To monitor the humidity level inside the chamber.
Steps to create a shotgun fruiting chamber:
1. Prepare your container:
- Clean the plastic container to ensure it’s free of any potential contaminants.
- Drill holes in the container’s lid, sides, and base to allow for air exchange. Make sure the holes are evenly spaced (10–15 cm apart) and approximately 6 mm in diameter. These holes allow fresh air in and carbon dioxide out, which is vital for healthy mushroom development.
2. Fill the bottom with perlite:
- Pour a layer of perlite about 5–7 cm deep into the bottom of the container.
- Soak the perlite with water until fully saturated, allowing excess water to drain from the base. The perlite should be damp but not submerged. The water held in the perlite will slowly evaporate, helping to maintain high humidity levels inside the chamber.
3. Add a hygrometer (optional):
- Place a hygrometer inside the chamber to monitor the humidity level. You can read it through one of the holes or attach it to the side of the container. While not strictly necessary if the perlite stays hydrated, a hygrometer can help ensure the environment remains at or above 90% relative humidity (RH), especially in drier climates.
4. Place your substrate inside:
- Once the chamber is set up and conditions are stable, place your mushroom substrates or fruiting blocks inside.
- Ensure that the substrate is not in direct contact with the perlite. Use a plastic spacer or similar support to provide at least 2 cm of clearance between the substrate and the damp perlite to avoid waterlogging.
5. Monitor and maintain conditions:
- Regularly check humidity levels. If the perlite begins to dry out, rehydrate by spraying only the perlite and the inner walls of the container—do not spray the mushrooms or substrate directly.
- For proper air exchange, remove the lid and wave your hand or a clean object over the container twice daily. This will help release built-up CO₂ and draw in fresh oxygen.
The shotgun fruiting chamber should provide a high-humidity environment with good air exchange, both essential for the fruiting stage of mushroom growth. To avoid contamination and ensure continued success:
- Wash the container after every 1–2 flushes.
- Replace perlite if it becomes heavily discoloured.
- Perlite can be cleaned and reused by rinsing it in a bleach solution (1:10 ratio of bleach to water), then thoroughly draining and drying it before use.
With regular upkeep and good hygiene, a shotgun fruiting chamber can support multiple successful flushes and a healthy mushroom harvest.