How to Build an Incubator for Magic Mushrooms

Why use an incubator for magic mushrooms?

Which are the best conditions for magic mushroom development? Magic mushrooms grow at temperatures where any human being would be comfortable. For growers who aren’t concerned about getting the best yields possible, placing incubating jars in a box on top of the fridge will do.

However, a magic mushroom incubator will maintain the best condition for jars and bulk substrate trays. The incubator will keep the substrate jars at temperatures of 82 degrees F while the temperature inside the jars will be 1 to 2 degrees warmer. This temperature will also make jars and trays produce mushrooms faster.

Building a magic mushroom incubator is a race against time and a race against contamination. Once jars are fully colonized, they become less conducive for contaminants to take a hold of. Hence, anything that speeds up mycelia growth (such as magic mushroom incubators) is a good thing.

Building an incubator is optional but it’s highly recommended.

Building a magic mushroom incubator – what you need!

In order to build a magic mushroom incubator, you will need the following supplies and equipment:

  • A large plastic cooler
  • Aquarium heater (submersible and saltwater safe)
  • Big plastic jug with a tight lid (should be large enough to fit the water heater)
  • 12v power supply
  • Two small 2v computer fans (or processor fans)
  • Glue

Don’t use a metallic cooler because of the wires and electricity involved. A plastic cooler’s flexible lid will also keep your wires from getting pinched when the lid is closed and opened.

Steps in making a magic mushroom incubator

Modification of the jug’s lid is important. You need to be able to run the wires through it and still close it tightly even with the aquarium heater inside. The jug should have a water tight seal with the heater inside.

Use a good quality jug to make for easier sealing. You can also use any large plastic bottle, preferably a 2-lliter soda bottle. This process will involve plenty of silicon and duct tape if you’re using regular bottles.

Make sure the jug can seal well otherwise the hot water will easily evaporate from the inside of the incubator and will drop with humidity. Leaving openings for evaporation also means having to open the jug back up to refill it with water regularly. An aquarium heater that runs even partially dry will burn out quickly, possibly starting a fire. Hence, a water-tight seal is necessary.


incubator | Image powered by shroomery


The jug, with the aquarium heater sealed inside, is now called a heat bomb.

After all the glue on the heat bomb is dry enough, add 5 or 6 tablespoons of salt and fill it up with tap water. Check for any leaks and seal them up when you find them. The heater should be 100% submerged 24/7 to avoid burning out.

To avoid microbes from growing in the warm water inside the bomb, add salt. The salty environment will make it hard for them to proliferate inside the incubator.

You can use any aquarium heater but the Won Brothers Pro Heat is probably the best choice for this method. The Won Brothers Pro Heat heater is a good investment for budding mushroom growers because it has an easy to adjust dial, a remote thermal probe, and a digital temperature display.


BT3 | Image powered by viot


Don’t place the remote temperature probe inside the heat bomb. Place it on the wall of the incubator as far away from the heat bomb and fan as possible. Meanwhile, the heat bomb should be placed inside, at the very center of the cooler, not on one of the ends or corners.

heat bomb


Attach the little computer fans by gluing them high on the incubator walls at an angle aiming at the bottom of the cooler. Don’t allow the fans to blow directly onto the temperature probe. Wire the fans to a 12v power supply and tape up the wires to the side of the cooler. The fans should run continuously to prevent the formation of hot spots inside the incubator.


Close the incubator and allow it to run for a few hours. Once it’s running smoothly and you’re sure it won’t explode or catch fire, close the incubator and don’t open it for 24 hours.


Once you open the incubator after 24 hours and you see plenty of condensation when you open it, it means you have leaks inside. Re-inspect and seal up the leaks. The inside of the incubator should remain dry.

After running for 48 hours, the temperature inside the incubator would have become more stable. Use a thermometer to test the accuracy of the heater’s control dial. Set the temperature at 81 or 82 degrees F. If you’re unable to hit the ideal temperature, go cooler. Any temperature warmer than that will only bring trouble for your mushrooms.


At the end of this process, you’ll have a big plastic cooler that’s capable of maintaining a specific temperature. You have completed the steps in building an incubator for magic mushrooms.

Final notes on building a magic mushroom incubator

Make sure there’s plenty of space inside the incubator. The space will help air flow more freely inside the incubator. By allowing air to move inside, heat is distributed more evenly. Without an air current and without space, the heat bomb will become much warmer and can possibly put your growing mycelia at risk.

Don’t overcrowd the incubator with many jars or trays. This will cause hot spots to form and the results will suffer a great deal. Build another incubator instead of filling the incubator beyond capacity.

Depending on the incubator size, the heat bomb will run anywhere from 4 to 10 degrees warmer than the ambient temperature inside the magic mushroom incubator. To maintain the ideal temperature, don’t be afraid if the heat bomb may have to run from 86 degrees to 95 degrees F.

Now that you know how to build an incubator for magic mushrooms, give it a try! Take your next magic mushroom grow to the next level and construct an incubator!

One Response to “How to Build an Incubator for Magic Mushrooms”

  1. Eugene McCormick 16th June 2019 at 23:02 #


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