Growing Mushrooms At Home: How To Make A Mushroom Fruiting Chamber

How do I make a mushroom fruiting chamber?

There are many ways to grow mushrooms at home. You could use hydroponics or soil. You could use a light house with a greenhouse, or you could build your own home grown mushroom growing chamber.

Hydroponic system uses water and nutrients to grow plants. It’s easy to set up and maintain, but it doesn’t produce as much food as soil does. Hydroponics requires less space than other systems like soil because you don’t need to dig down too deep into the ground. However, it takes longer to grow your crops.

Seedlings take 3 months to mature from seedling stage to harvestable size. Once they’re ready for consumption, you have to wait another year before harvesting them again.

Soil is the most common method used in cultivation today. It’s very simple and easy to set up and maintain. Soils are made of organic material such as composted human waste or manure (which contains beneficial bacteria).

Plant roots need water and nutrients to grow. Water is the most important because the plants will die if they don’t get enough of it.

Most people think mushrooms are grown in the dark, but it’s not true. Mushrooms are actually grown in dimly-lit places because they’re very sensitive to light. They grow on logs, stumps or sawdust blocks because they like rotting wood.

The best temperature for growing mushrooms is 21 degrees Celsius. The place where you grow your mushrooms should be neat and clean because mushrooms are very particular about their surrounding. When ready, cut up the mushroom and add it to your meal. You can also dry it to preserve its freshness and eat it later.

Forget going to the market to buy fresh, home-grown organic produce. With a little effort and know how, you can start growing your own organic mushrooms at home!

How to make a mushroom fruiting chamber

Here’s a step-by-step procedure on how to make a simple, yet effective uninsulated, one log mushroom fruiting chamber.

You’ll need the following:

One 2′ x 6′ (0.6m x 1.8m) sheet of 3/4″ (2cm) thick plywood.

One 3/4″ (2cm) diameter dowel – 8 feet (2.4m) long

One brick

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One short length of 2″ (5cm) diameter galvanized pipe

One roll of 1/2″ (1.3cm) hardware cloth

Four 8″ (20cm) deck screws

One container of 1 1/4″ (3cm) galvanized roofing nails

Nine – #8 ring shank nails (2 1/2″ – 3″ – 3.5″ – 4″ – 4.5″)

One tube of caulking (caulk)

One large box of 1 1/2″ (3.8cm) nails

Two cubic feet of coarse sand (large bag)

1.5 cubic feet of vermiculite

One quart of linseed oil

One quart of polyurethane

One extension cord

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Various drill bits including a 1″ (2.5cm) diameter drill bit

Masking tape


First, draw two lines, each 4’3″ (1.3m) long at the bottom of the sheet of plywood. Next, draw two lines, each 2’3″ (0.7m) long in the top half of the plywood sheet.

The lines in the bottom should be parallel to each other, and the lines in the top half should also be parallel to each other. The corners of the plywood sheet should also be at 90 degree angles.

Assemble the 8 foot long dowel and the brick into a box-like structure, with the bottom of the box touching the lines in the bottom of the plywood sheet. The top of the box should be 4’3″ (1.3m) above the top of the plywood sheet. Nail the dowel into place using 2 1/2″ (6cm) ring shank nails (nine nails in each side).

Take the piece of 2″ (5cm) diameter galvanized pipe and drill a 1″ (2.5cm) diameter hole through its center. This is the hole where the fruiting chamber’s exhaust duct will be installed later on. The duct should point upwards towards the bottom of the box at an angle.

The top end of the pipe should be 2’3″ (0.7m) above the bottom of the plywood sheet. Nail the pipe into place using two 4″ (10cm) nails (one at each end).

Run a line of caulking along the perimeter of the top of the plywood box.

Nail the hardware cloth into place so that it covers the top of the box and the brick. The wire of the hardware cloth should be facing inward, towards the box. Nail the hardware cloth into place using 1 1/2″ (3.8cm) nails (nine nails on each side).

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Mix the two cubic feet of coarse sand and the one and a half cubic feet of vermiculite. Add water to the mixture until it has a consistency roughly equivalent to cookie dough. Stir the mixture thoroughly, making sure there are no clumps of dry sand or vermiculite. This is the mushroom substrate.

Add a small amount of substrate into each of the lines in the plywood sheet. Press a sheet of newspaper onto the top of each line of substrate. The newspaper will be removed later to allow the substrate to dry.

Cover the box with the tarp. Place a brick in each of the upper right hand corner, and the lower left hand corner of the tarp. This will keep the tarp from blowing away in the wind.

Add a small amount of water to the substrate every ten days or so. Just water, no nutrients. The substrate should be damp like a wet sponge, but no water should drip from it. If it begins to dry out, add a small amount (teaspoon or less) of water every two to three days until it stops drying out.

When the substrate is well on its way to being colonized by the mushroom mycelium, slowly pull the newspaper out from underneath the substrate. Leave the newspaper above the substrate exposed and pinned down with clothespins. In about two weeks time the mushrooms should be ready to harvest.

Once the mushrooms have grown to a decent size, they can be cut from the substrate and eaten.

Repeat steps 17-20 for the rest of the substrate. The boxes will be ready for another harvest in about two weeks.

Once you have harvested and consumed all the mushrooms in all the boxes, mix together 3 cubic feet of manure, 1 cubic foot of coarse sand, 4 cubic feet of vermiculite, and one cup of hydrated lime. Moisten the mixture as you did with the first batch of substrate.

This mixture can be used to refill the boxes. If the mushrooms have exhausted all of the nutrient rich substrate, add another 1/2 cup of hydrated lime. Once this mixture has been added, the box should be ready for another harvest in two weeks.

To use the second batch of substrate, fill each box with substrate and remove the newspaper as before. The boxes will be ready for harvest in two weeks.

Note: It will take about a week of time to complete this project. Also, it is recommended that you do not use the same containers for the second batch of substrate that you used for the first batch. The first batch of substrate will have become contaminated with mushroom spores by the time you are ready to fill the boxes for the second batch. The second batch of boxes can be filled using the same procedure as the first batch.

Once the four boxes have been prepared and are ready for harvest, they will provide about eight weeks worth of shiitake mushrooms. Each box will produce about one and a half pounds of dried mushrooms every ten days.

You can extend the life of the mushroom substrate by a few days if you add a small amount of nutrients to it. To do this, mix 1/2 teaspoon of hydrated lime with one cup of water. Let the mixture stand for a few days to create “lime water”. Add 1/2 cup of the “lime water” to the substrate every 10 days or so.

Once the second batch of substrate has been mixed in the boxes, there will be no more nutrients for the mushrooms to feed on. To extend the life of the box, fill each box two thirds full with wheat bran. The mycelium will digest the wheat bran and provide food for the mushrooms. Be sure to keep the boxes covered with plastic until the mushrooms have grown out of the top of the boxes.

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One of the largest problems that most amateur mushroom cultivators face is a lack of air exchange, leading to a buildup of carbon dioxide and a lack of oxygen. To combat this problem, simply drill 20-30 one inch holes in the bottom sides of the box and add rubber weather-strip around the lid of the box. This will allow plenty of fresh air to reach the mycelium and prevent the buildup of toxic gasses.

As the mushrooms grow, they will displace some of the straw and push up the lid a bit. To keep the boxes self-supporting, add a 2″x4″ between the top of the lid and the boxes. This will help keep the weight of the mushrooms from crushing the mycelium on the bottom of the box.

These boxes can be stacked by adding 2″x4″‘s between each layer as well. The boxes will also be easy to move when filled with substrate and mushrooms.

You can make these boxes in a variety of different sizes, depending on how much substrate you want to work with. For example, the first box can be made in a standard 5-gallon paint bucket to hold four cups of substrate. Each successive box can be made in a 6-quart, a 2-gallon, or a bucket that holds three to four gallons.

The above method can also be used for growing edible mushrooms such as oyster and shimeji. (edible mushrooms should NEVER be grown on wood chips, as many guides recommend, because poisonous mushrooms can be easily confused with edible ones)

For edible mushrooms, a good mix of chopped hardwood or softwood makes a good substrate. If you use softwood, such as pine, do not use wood that has been exposed to pesticides. Doug fir is an excellent choice. The mixture should be 2 parts hardwood to 1 part softwood.

Fresh wood should be chopped into one-inch cubes no larger than a fist and allowed to air dry for approximately one year before using.

Once you have created a wooden substrate, mix in 2 or 3 cubic feet of coarse sand, a half-cup of hydrated lime, and a half-cup of hydrated limestone (not regular cooking limestone). Once this mixture is thoroughly mixed, it should be ready to inoculate.

As with growing mushrooms on straw, you can use plastic totes, Rubbermaid containers, or wooden boxes for growing mushrooms. Wooden boxes will probably give the best results, as ill keep your substrate evenly moist and provide a better environment for your mycelium to grow and spread.

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You can buy plastic lids for five-gallon paint cans that will form a perfect lid for your box. Drill 1/2″ holes in the bottom for drainage.

After you have prepared your container, drill 1/2″ holes over the entire bottom side of the box for drainage. Cut a 2″ wide strip of plastic sheet and place it around the rim of the inside of the box. This will keep the excess water from running over and leaking out of the holes in the bottom of the box.

Once you’ve drilled all your holes, mix your substrate in a wheelbarrow or something similar. Add water, mixing it in by hand until it’s too hard to work anymore. If you can squeeze a handful of substrate and only a few drops of water come out, then it’s ready to be filled into your containers.

To fill the box, start with the back corner on your right (if you were facing the box). Pack the substrate in tight and even as you fill it in the container.

Once the container is full, use a board to flatten out the substrate in the box, making sure that there are no high-point that could act as a water pool. A glass coke bottle works well to even out the surface.

Once the box is filled, you’re ready to introduce the mushroom spawn. Dump a packet of mushroom spawn (available at most garden centers) into a bucket or similar container. Add a cup of water and stir or shake until the mushroom spawn is completely broken up into small pieces.

Pour the spawn out onto your box of substrate and use your gloved hands to spread it evenly over the surface. It should be anywhere from the thickness of a quarter to a dollar on top.

Place a plastic cover or a wooden board with holes in it (to keep out insects) on the box to hold in the moisture and keep out insects.

The spawn will begin to grow mycelium within two weeks and then start to pop through the top in another week or two. Once the box starts producing “fruit” you can begin harvesting.

Sources & references used in this article:

Cultivation of Pleurotus ostreatus and other edible mushrooms by C Sánchez – Applied microbiology and biotechnology, 2010 – Springer

DIY FunGuide: Grow your own Oyster Mushrooms at Home by CM Hsu, K Hameed, V Cotter, HL Liao – EDIS, 2018 –

Growing gourmet and medicinal mushrooms by P Stamets – 2011 –

Cultivation of edible ectomycorrhizal mushrooms by IR Hall, W Yun, A Amicucci – TRENDS in Biotechnology, 2003 – Elsevier

… Essential Guide to Cultivating Mushrooms: Simple and Advanced Techniques for Growing Shiitake, Oyster, Lion’s Mane, and Maitake Mushrooms at Home by S Russell – 2014 –

Psilocybin mushroom handbook: easy indoor & outdoor cultivation by LG Nicholas, K Ogame – 2006 –

Waste to Fungi: An EPS@ ISEP 2019 Project by A Winter, E Pedro, J Ślasko, J Battaglini… – Proceedings of the …, 2019 –

DIY Mushroom Cultivation: Growing Mushrooms at Home for Food, Medicine, and Soil by W Arevalo – 2019 –



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