Introduction: Personal Mushroom Farm


This project was mainly done for participating in the US-China Green electronic Challenge. If you like our project, think it is interesting or just want to make our day, we appreciate a vote for this. Thanks and enjoy our project description :)


Nowadays lifestyle in China is characterized by a strong urbanization. People move from the countryside to the cities, live in small apartments. Although people actually want to live in the city, especially in European countries and in the US a strong counter movement of urbanization takes place. People start growing their own vegetables and fruits in small community gardens like the German Schrebergarten (British English: Allotment garden; Chinese: 社区农圃) are a common sight in western countries, and even public spaces, like parks, are used for this in a project called “Urban Farming”. People grow their own herbs at home to avoid the lower quality of mass products (e.g. in a window farm) and even make their own honey by domesticating bees on the balcony, the terrace or in garden. Some people even grow wine on their rooftops and process the juice with small scale equipment, people brew their own beer or burn their own liquor out of fruits, which is mostly legal if done for private use in small scale. Those activities can be clustered to “Urban Agriculture”. Those activities are mainly done as recreational activity or hobby, as political statement (against consumerism/capitalism and for sustainability) and out of food safety concerns and not out of monetary reasons.


When we wanted to take part in this contest because of a class, our given target was to create a product within a short time scale (7 days) from 0 to the finished product and with a very limited budget. First we were browsing our homes for unused electronics, where we found a broken mobile phone, an unused air humidifier, and old (manual) thermometer/ hygrometer and an unused laptop cooling base. From those products we chose the air humidifier and got two different ideas for using it:

Combine the air humidifier with an electronic hygrometer and create an automated air humidifier with adjustable relative air humidity and building a greenhouse for plants that need a high relative air humidity. Since we didn’t have an electronic hygrometer, we chose the second idea. To emphasize on the green aspect, we combined it with the idea of “Urban agriculture” and “Home Farming” to use it as a greenhouse for growing mushrooms.

More information and sources:

Step 1: Construction of Device

Used electronics:

  • A used ultra sound air humidifier we wanted to throw away (costs for new product: 69 Yuan RMB)

Other things used:

  • A water tank from a water dispenser (Deposit costs of around 50 Yuan RMB)
  • Small hose
  • An old analog thermometer/ hygrometer (costs for new product: 19 Yuan RMB)
  • Hot glue
  • Tape
  • File
  • Saw
  • Kitchen Knife
  • Grinding paper

For the growing:

  • A 4l plastic bottle as bowl
  • Cardboard as substrate
  • Honey to add some more nutrients to the substrate
  • 1 - 2 Oyster mushrooms for “cloning” the mycelium
  • Boiling hot water for pasteurizing the substrate
  • Sterilized water for using in the air humidifier

Step 2: Step 1.1:

Cut open the water tank by using the saw (We tried using a kitchen knife, but the tank is to stable for it). The water tank we used had a wider section right at the opening, where we sawed it, so that we can use the smaller part as a lid for later. After the sawing we smoothened the edges by using the file and grinding paper.

Step 3: Step 1.2:

Attach the hose to the opening of the water tank and seal it by using hot glue and tape. The other side of the hose is attached to the removable lid of the air humidifier and also sealed.

Step 4: Step 1.3:

Glue the thermometer/ hygrometer to the tank’s wall from the inside. It should be readable from the outside, even when there is a lot of moisture.

Step 5: Step 1.4:

Put the two parts of the water tank together. If they do not close so well, help yourself by adding some tape/ hot glue on the edges or grind material away with grinding paper. It doesn’t need to be 100% sealed, but the majority of the moisture should stay inside. We do not fix the lid in its final position before we put the self-made plastic bowl into it. (See steps at farming). If the plastic bowl is prepared and inside the tank, we attach the lid with some tape.

Since this is somehow our prototype, we found some ways to improve the construction or upgrade it:

Possible improvements:

  • Using a transparent water tank instead of a blue one to have a clearer view on the mycelium grow.
  • A more elaborated lid which is easier to open / close and is sealed.
  • A leveled shelf to grow more mycelium colonies at once.
  • A timer switch for the air humidifier (needs to be tested beforehand)
  • An electronic thermometer/ hygrometer
  • Add a nice sign on the tank

Step 6: 2 Mushroom Farming:


Mushrooms are the fruit bodies of bigger organisms called fungi (singular: fungus) which are an organism between plants and animals. The lifecycle of mushrooms starts with spores which if under the right condition (usually moist condition) develop a web like structure called mycelium. Out of this mycelium fruit bodies can grow (under certain conditions, which differ from the one before) to mushrooms, which again produce spores. The largest known fungus is at the same time the largest organism on the earth, a honey fungus in the Blue Mountains, Oregon, USA. This fungus spreads over an area of 8.9km² (2,200 acres), is 2400 years old and weighs 609 tons. Fungi can be classified into many different species, some are toxic, whereas some are edible. It is important to note, that not all mushrooms can be grown by humans, since some species need a tree or root as symbiosis partner, and thus can just grow in the nature.

Step 7: Step 2.1:

The farming process can be divided into different smaller processes. First of all, we need something the fungus can grow on, the substrate. Based on the kind of mushroom used, there are certain requirements. We will grow the mushroom with the lowest requirement, the oyster mushroom (Chinese: 平菇). For this kind of mushroom the substrate can be nearly anything organic as can be seen in the following list:


  • Liquid substrate (around 4% aquatic solutions of honey, malt extract, glucose or other kind of sugars)
  • Cereals (rye, wheat, barley, millet, corn, rice…)
  • Wood chips, saw dust (everything but pine trees or oaks)
  • Straw (Cereals, corn, legumes; Cereal straw does not contain enough nitrogen and protein and should be mixed with other kind of straw)
  • Paper/ Cardboard (e.g. old cardboard boxes, toilet rolls; printed paper should be avoided due to toxic printing colors)
  • Coffee dregs (vulnerable for molding)

For the device we use cardboard, which we cut into smaller chips, and soak it into a liquid aquatic honey solution. For processing the card board, it needs to be sterilized to kill unwanted spores, like mold spores. Therefore we use boiling hot water to soak the cardboard ships for a while. We also use boiling water to clean all the apparatuses. This step is very vital, because whenever there is any mold on the mushrooms, it is toxic and not edible any more.

Step 8: ​Step 2.2:

Now we add the fungus onto the card board. There are essentially two methods: Infusing with spores or cloning. Since we would need to buy additional spores (which is by the way necessary for nearly every other mushroom than oyster mushroom), we use the cloning method. Therefore we just buy one or two mushrooms in the market, cut them into two pieces and put them onto the substrate. Then we put the bowl with the substrate into the water tank, close the tank with the lid and fix the lid with tape. We then turn on the air humidifier to make the right environment (please refer to the manuals in the references or the one you can find on Google to find the right parameters for each type of mushroom). This phase is the growing phase, where the fungus grows the mycelium throughout the substrate. It is complete after around 2 weeks, when there is a visible white structure on the substrate.

Step 9: Step 2.3:

This step will trigger the fruiting phase of the mushroom with a cold shock. The plastic bowl is therefore wrapped with foil to keep it moist and then put in the fridge for around 2 days. For oyster mushrooms this step is not necessary, but can accelerate the fruiting, which else needs one week after the mycelium is done growing.

*note: since we are not in this phase yet, the used photo is just a placeholder*

Step 10: ​Step 2.4:

After the triggering of the fruiting, the plastic wrap is removed and the bowl is again put in the water tank. The environmental conditions differ from the growing phase, e.g. a colder place is needed, a little less humidity and more fresh air and especially light. (see table at 2.2) This phase takes around 3 weeks.

*note: since we are not in this phase yet, the used photo is just a placeholder*

Step 11: ​Step 2.5

If everything is done correctly, the mushrooms are ready for harvesting and eating. Before eating, check the mushrooms for visible signs of mold (any colored parts). If you find mold, unfortunately the whole harvest is not safe to use anymore. A simple recipe can be found in the link (growing oyster mushroom on a toilet roll) or somewhere else in the internet.

More information and sources: (German (comprehensive book about mushroom farming)) (German (Manual for growing oyster mushrooms)) (Manual for growing oyster mushrooms on a toilet paper roll) (growing oyster mushrooms in a bucket) (six step guide for farming mushrooms (in larger scale))

Green Electronics Challenge

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Green Electronics Challenge

Gardening & Homesteading Contest

Participated in the
Gardening & Homesteading Contest

Green Design Contest

Participated in the
Green Design Contest