January 31, 2013

Build your own Auto – Terrarium for $80 Bucks or Less | Growing Magic Mushrooms

A terrarium is an artificial habitat that mimics your magic mushrooms natural ecosystem. It is used to ‘fruit‘ your substrate cakes and yield you mounds of fresh, highly potent fungi.

NOTICE: This post does not cover making SUBSTRATE CAKES which requires separate supplies and is covered HERE.


The INSTRUCTIONS detailed here will build an optimized terrarium that grows magic mushrooms automatically.

Why buy an overpriced auto terrarium when you CAN build your own for $80 bucks or less? A working auto terrarium makes your only real work picking and drying the magic mushrooms.




Terrarium Building 101 – Principles of Operation

Building a terrarium is very simple. Once you understand the basic concepts of what makes a ‘good terrarium’ it becomes even easier to design and build your own custom containers. A terrarium also know as a ‘fruiting chamber’ (FC) needs 3 basic elements in order to grow the best possible magic mushrooms:


  • Fresh Air Exchange (FAE)A constant supply of fresh air is circulating throughout your fruiting chamber what you want. Fresh air is an indicator to the substrate cakes to start growing. The constant exchange of fresh air also exhausts any built-up co2. This prevents slow or stunted growth and inferior quality mushrooms.
  • High Relative Humidity (RH) – Mushrooms themselves are about 92% water and need a very humid environment in which to grow. You need about 95% RH for your colonized substrate cakes to produce optimally. Anything less and your yield may suffer.
  • Contaminant Free EnvironmentA sealed fruiting chamber will not allow outside contaminants a chance to get inside. All air before it enters the terrarium is filtered through the air pump. The exhaust allows air and Co2 to escape but through positive pressure no air is allowed in.  A clean contaminant free fruiting chamber means you’ll never have to worry about infected cakes or mushrooms.


CLICK to Enlarge


The system works by using the ultrasonic mister to atomize the water in the first smaller sealed container. The air pump pushes this ultrasonic mist under mild pressure into the second larger ‘fruiting’ container. The height of the first container is important since the damper mist will tend to be heavier and will sink to the bottom of the container. This means that the lighter mist at the top is pumped into the terrarium. 

There is an almost infinite number of containers you could use to make the humidifying unit as long as the container seals air tight with a removable lid and is at least 7″ inches (19mm) in height. The example terrarium built here used a container roughly like THIS ONE which was previously filled with 58.5 fl. oz of miracle whip. 

Unlike using conventional humidifier there is no need to worry about too much air-flow or too much moisture. The air pump and sealed containers act as an air-lock/positive pressure system that does not allow outside contaminants in. The system is very water efficient and in many circumstances operate for an entire grow cycle on a single fill of water.


  | Video Overview |

| Download Full Materials List (pdf) | Skip to Instructions |

Basic Building Materials

Clear Plastic Bin ( Sterilite | Ultra Latch – 30Qt./28L ) – is used as your fruiting area. Growing magic mushrooms requires an extremely humid environment. Plastic containers are a cheap means of containing all that moisture and are easily modifiable. Many different plast ic containers can be used however make sure that the container is clear and the lid seals well.



Sealed Plastic Container (Approx. 1/2 Gal. to 60 fl. oz) – will be adapted for and used to create the humidifying unit that will be attached to your fruiting chamber. You can adapt many different containers to use however a half gallon container with a seal-able lid works best. A 60oz miracle whip container was used to create the humidifying unit here. 


Ultrasonic Mist Maker –  this item atomized water to produces a super fine mist that resembles the fog that Mother Nature produces naturally. This fog contains microscopic droplets of moisture which is easy to absorb and nourishes for your growing magic mushrooms.


Air Pump – The air pump creates the pressure needed to pump the ultrasonic fog into your fruiting chamber and exhaust any built up Co2.  The pump also filters the air it pumps into your terrarium. Bigger the better. Couple with an air stone to further oxygenate your magic mushrooms grow environment.

Aquarium Air Hose & Barb – This is standard aquarium hose line that connects the output of your air pump into your humidifying chamber along with the appropriated sized hose barb.

1/2″ Nylon Hose Barbs, Elbow Barb & Tubing – These connectors and tubing attach your humidifying unit/container to your sealed Sterilite terrarium and create the exhaust to flush out stagnant Co2.

Small Stacking Shelf – Placed comfortably in the center of your terrarium on top of the perlite the small stacking shelf should be of sturdy wire construction with a stackable/lockable leg design.


Perlite – Is made of small pieces of extremely porous volcanic rock and is used to line the bottom of your terrarium. Under a microscope you’d see that the perlite has many large holes resembling swiss cheese. When water is added it is wicked into these porous holes. This porous structure allows the slow evaporate of moisture back into the air. This evaporation process keeps your terrarium humidified even when your humidifying unit is not running. Coarse perlite works best for terrariums.


Don’t forget… Download the Full Materials List (pdf).


Got no $Cash$… Then build a Shotgun Terrarium

Terrarium Construction Instructions


 1) Create a Hatch and Window

On top of the sterilite plastic bin’s lid outline a large rectangle to act as the hatch. In the center the rectangle you just outlined mark out a second smaller rectangle for the window.

Use a dremel and cut out the center rectangle first. On the second rectangle cut all sides except the back.

Lift and wrap window in cellophane. Tape the window edges with heavy duty duct tape. Add a small knob to help you lift your hatch by drilling a tiny pilot hole and adding a small screw.

 Terrarium Build

Seal the entire hatch with tape starting at the edge of window and over the edges of the entire rectangle. This is more of an art than a science so take your time. In the end the hatch should stick and seal but still be able to easily peel back and open.

Terrarium Build Part2b



2) Install Terrarium’s humidifier Input and Exhaust

Place your elbow barb on the front right corner of your terrarium’s lid and carefully trace around it’s edges.

In the center of the circle you just outlined drill a hole.From this pilot hole use a dremel and chissel out a hole that barely reaches the edges of your marked circle. 

If done correctly you should be able to screw in your 1/2″ elbow hose barb. The fit should be very snug and when fully tightened be air tight.

Repeat this process to install your other straight 1/2″ hose barb to the back bottom left of your terrarium two inches from the bottom. Screw in the threaded end with the barb portion ending out.

Next cut out a small square of screen mesh and wrap it over the end of the barb. Either tape or rubber band the mesh tightly around the exposed barb.

Cut a finger off a vinyl/latex glove. Slip the end over the mesh covered barb. Seal the glove finger tight around the barb with heavy duty duct tape.

Cut a tiny slit in the end of the finger. Now when the air is on the finger will inflate and exhausted air will be pushed out. If the pump is off the finger deflates.This effectively helps keep positive pressure and potential contaminates out.



3) Prep your Bin and Seal the Lid

Break off the handles on your bin. The holes that held these handles will have to be sealed. Tear off some tiny pieces of tape and seal the holes from the outside.

Next press out a dab of silicone sealant over the holes from the inside. Flip over your terrarium lid and line the inside with waterproof silicone sealant.

Place the lid back on the bin and allow the silicone sealant to cure and dry.


4) Build an Ultrasonic Humidifier

Drill a hole in the lid of your small sealed plastic container for the other straight 1/2″ hose barb. Screw in your hose barb and attach one end of your 1/2″ tubing.


On the body of the container itself drill a hole for your mist maker power wire and cork plug. Make sure the hole is a good four inches from the bottom.

Now Attach a small strip of industrial velcro first to the bottom of the container then to the bottom of your mist maker.

Install the mist maker by attaching it to the bottom of the container and threading the power cord out of the adjacent pre-drilled hole.

Press the cork plug until it sits tight and seals the hole. You don’t have to seal the plug with silicone as not doing this make it easy to exchange your mist maker if you need to replace it for any reason.

Next drill matching hole for the aquarium airline hose barb. The airline hose barb should fit snug and tight inside after which you can seal with silicone if desired.

Cut off a small length of airline and attach an airstone. Place it inside the container and connect it to the inside end of the airline hose barb.



5) Final Setup

Before starting this last phase make sure to thoroughly clean the inside of your terrarium and humidifier with rubbing alcohol.

Next fill your ultrasonic humidifier with spring water until the water line is about an inch and a half above the top of your mist maker. 

Place everything on a flat surface and take the end of the hose coming from the ultrasonic humidifier and connect it to the input barb on the top of your terrarium.


Sterilize and bake your perlite at 350 for 30 minutes. After it has cooled rinse the perlite in a strainer under the faucet.

When the perlite has drained well dump it into the bottom of your terrarium.

Add a 2″ layer of damp but not wet perlite. This will help maintain your terrariums humidity.


Lastly connect your air pump to the airline hose barb of your ultrasonic humidifier.

Leave your air pump on 24/7 to keep a constant supply of fresh air flowing through the terrarium. Plug the mist maker into the timer. Set the timer to switch on for 15 minutes every 4 hours. This setting is only a general rule. Often set-ups take a certain amount of individual tweaking before producing good results. Bear this in mind.

Download Materials List (pdf).

Got no $Cash$… Then build a Shotgun Terrarium

At this point your terrarium is ready for FRUITING all you need to do is place some fully colonized substrate cakes inside!

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Filed Under: DIY Projects, Growing


  • vik

    March 29, 2014 at 3:04 am

    does it need any kind of heat or light source?

  • Tim

    June 22, 2014 at 3:51 am

    where do you find the barb back draft exhaust? can’t seem to find anywhere

  • Tim Gene

    June 22, 2014 at 3:52 am

    Where do you buy the back draft exhaust or something similar? can’t seem to find one

  • Chris

    July 23, 2014 at 2:49 am

    You spray the spores onto the perlite?

  • Toxie

    November 28, 2014 at 12:31 am

    I have basically the same thing. I have a humidifier found at http://www.universityscientific.com/product.php?xProd=55&xSec=2 I’m starting to think I don’t need the perlite. If my cakes are on a rack, and the excess humidity drops to the bottom, then I don’t need perlite to hold the water do I? What do you think?

    • Buds McGee

      November 29, 2014 at 5:28 pm

      Yea, you could probably get away with no perlite. Though one thing about adding perlite is that it will absorb excess moisture, and then release it back into the air. Having perlite will keep any water from pooling on the bottom of your terrarium. Stagnant pools of water can breed contaminants. But I understand that perlite can be a mess to work with. Thanks for the comment.

  • PufDaddee

    November 27, 2015 at 4:49 pm

    I experimented with a simplified version of this. Instead of a separate chamber for the air diffuser and ultrasonic mister, I put them in the bottom of the terrarium, which has about 2 inches of tap water instead of perlite. On startup, I added some hydrogen peroxide to the water but I’m not sure that is necessary as the air diffuser keeps it from becoming stagnant. I also didn’t bother with the exhaust barb or carefully sealing the top lid. It seems to work very well as I’m on my second batch.
    Initially I used just two 6-inch aquarium air diffusers while waiting for my ultrasonic misters to arrive. After adding the mister, I think the humidify is actually too high because large drops of water are forming on the cakes. Today, I turned down the air supply to try to reduce it a bit.
    (Ideas/comments/feedback welcome).

    • Buds McGee

      December 12, 2015 at 1:36 am

      Great to hear about your experiments, and thanks for posting your comments. I would love to see a picture of what you described. Sounds like your tweaks are working well for you. Yea, water droplets on the cakes is something to avoid. The excess moisture can drown the mycelium as well as open the cake up to contaminants.

  • jim

    February 28, 2014 at 7:12 pm

    Is the exhaust barb supposed to be above the perlite?

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