How To Make A Shotgun Fruiting Chamber (SGFC) For Mushrooms

Always thought it would be fun to grow your own magic mushrooms? Sufficient funds allow you to design a spacious growing chamber with fancy features, such as big fans and automated humidifiers. An easy-to-build shotgun fruiting chamber, however, will also do the trick—and it's inexpensive too! Read all about how a shotgun fruiting chamber works, and the exact steps you need to take to start growing.

What is a shotgun fruiting chamber?

A shotgun fruiting chamber is a makeshift mushroom terrarium that you can build yourself. Just following a few steps, a fully functioning chamber can be set up easily. Usually abbreviated to SGFC, a shotgun fruiting chamber is a great alternative to a more expensive, professionally built terrarium.

Why do I need a shotgun fruiting chamber?

You will only succeed in growing magic mushrooms if you can maintain an adequate growing environment. With a simple SGFC, you can easily create the ideal growing conditions for mushrooms to fruit properly. A great advantage is that it uses natural air currents to achieve this.

First of all, you need to create constant fresh air exchange (FAE) in the chamber, as well as sustain the high relative humidity that mushrooms require. An SGFC can be made out of a decently sized plastic tub with holes in all sides, covered in perlite at the bottom. As fresh air flows through the holes in the bottom, the wet perlite is what produces the humidity.

Make sure the tub is as clear as possible so your mushrooms get enough natural light. A completely transparent one will allow you to easily keep track of the whole process inside.

How to make a shotgun fruiting chamber

You only need a few tools and materials to make your SGFC. You will be growing your own magic mushrooms in no time! One of the essential materials is perlite. This natural volcanic mineral can soak up water, allowing it to consequently evaporate.

Equipment and materials

• Clear/transparent plastic tub with a lid
• Coarse perlite
• Power drill with 6mm bit
• Measuring tape
• Permanent marker

Directions

Follow our step-by-step guide below to build your own SGFC. If you already have all the necessary equipment and tools, you will be finished in less than an hour.

Choose the correct tub size

Make sure the bottom of the plastic tub is big enough to be covered in 10–12cm of perlite, while also leaving about 12–25cm head space for what you want to grow. Keep in mind that preventing uneven circulation is harder in tubs that are very big, while creating any circulation at all is a challenge with very small tubs. For this reason, we recommend a tub that can hold about 60–66 litres.

How many holes to drill in the tub?

Take the tub and use the measuring tape and permanent marker to draw the dots where holes should be drilled. Create a grid pattern with dots spaced 5cm apart on all six sides. This means all four sides around, plus the top and bottom.

Use the 6mm drill bit to drill holes through each dot. Make sure you do this gently, as too much pressure might cause the plastic to crack while you go through. Thoroughly check for plastic shards afterwards and ream the holes to make sure the edges are smooth.

Fill the tub with perlite

Ensure you have coarse perlite, because a very fine grind will end up completely spilling through the holes. Moreover, fine perlite won’t hold as much water. The exact amount of perlite isn’t super important, but a rule of thumb is a layer of approximately 10–12cm. Just make sure to cover the whole bottom evenly.

Add water

The perlite will already become a bit damp by rinsing it a few times before, which you need to do to get rid of dust. This is to prevent the holes from getting blocked by dust gathering at the bottom.

Once the SGFC is covered in perlite, add enough water to completely soak it all evenly by mixing it around with your hands. If water is spilling through the holes, you have used too much! You just need to coat the perlite with enough water to evaporate and create the right conditions.

Elevate the SGFC

Balanced FAE will only occur when fresh air can flow in through all sides, including the bottom. This is why you should elevate the SGFC instead of placing it directly on a surface. Simply improvise by putting some blocks or jars under the chamber in each corner. The distance from the surface should be approximately 5cm.

How to use a SGFC

You can now get started by placing your mushroom block in the chamber. In order for it to grow successfully, some light maintenance is necessary.

Fanning and spraying

Gas exchange will take place through the holes on all sides. However, to make sure there is enough airflow, you should lift the lid twice a day, at least, to fan in some fresh air. To prevent the air from becoming too dry after fanning, use a spray bottle to mist the walls and perlite again. This will help maintain the humidity level.

To avoid bacterial blotch or similar problems, don’t spray the mushroom block directly.

Misting Bottle (Zamnesia)

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Temperature and humidity

Over time, you will get the hang of which conditions are ideal for the different growing stages. The use of a thermo-hygrometer is therefore optional, but definitely helpful. It will make it a lot easier to find out whether or not the environment is humid and warm enough.

Hygrometer / Thermometer

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Sufficient lighting

Direct sunlight will warm up your SGFC too much and ruin your magic mushrooms, but they do need some natural sunlight during the day. Without enough light, the mushrooms can’t develop and fruit properly. Put the SGFC in a place where it gets indirect sunlight. Preferably near a window away from direct sun rays.

You can also use artificial lighting, such as a fluorescent light. To prevent the chamber from heating up, make sure the light is not too close. It’s also recommended to use a timer, switching it on for 12 hours and then off for another 12 hours. This way you can easily match a natural light cycle.

So, is a shotgun fruiting chamber worth it?

Building a SGFC can be done very quickly using inexpensive, easy-to-find materials and tools. With some moderate maintenance rules to consider, it won’t take you long to figure out how to achieve the perfect growing environment inside the chamber. This makes it perfect for those who are just starting to learn how to grow magic mushrooms. Moreover, for experienced growers. it would be practical to use simple growing chambers like these for side experiments.

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