Oesterzammen kweken

How to grow edible mushrooms

Bor Borren permaculture

The mushroom is a special phenomenon in nature as it is not a plant, but a mould. It mainly lives under the ground and it creates a big network in the soil. So, when you harvest a mushroom, you do not harvest one single mushroom, but just a part of a huge network. Also, there are way more types of them that we are aware of. This is due to the fact that they cross-breed which causes more types of mushrooms. Besides that, they make sure that the nutrients of dead organisms (animals, plants, etc.) come back in the natural cycle so they can be used again.

Growing your own edible mushrooms is a nice hobby and it fits perfectly in permaculture. However, it is actually not that easy and there are many ways to do it. For example, you can choose to coordinate with the appropriate season, so that means harvesting in the fall. When doing this, cultivating the mushrooms on wooden trunks is a good option. Another option is to buy complete trunks that already have spawn. You can buy these at, for example, Groene Takken. It is important to locate such trunks in a place with much shadow and moisture.

Making your own spawn

You can also make your own spawn, but this is very difficult as it usually made in a laboratory under sterile circumstances. Luckily, you can also buy spawn and place it in the pre-drilled holes of the trunk. Mycobois in Belgium is a good address to buy small portions of spawn. But, you can’t place every mushroom on every trunk. A shiitake, for example, grows best on a pedunculate oak.

Another method to grow mushrooms, is to make your own substrate where you can place the spawn in. With this method, you’re not dependent on the appropriate season. I also followed a workshop about this by Bruno van Haudenhuyse who’s from Belgium and is the creator of GandaZwam. The workshop was organised by Siemen Cox and Max de Corte in a garden in Rotterdam, called ‘Educatieve tuin de Enk’. Bruno created a substrate method that uses straw and coffee grounds. It sounds simple, but is actually needs much attention and hygiene to create the best circumstances for the mould.

Working method

De most important rule is that the ingredients contain as less bacteria and other moulds as possible. Therefore, sterilising the straw and coffee grounds is crucial. When you don’t do this, other moulds could start to grow and this could hold back the growth of the mould you actually want to grow. This could lead to a disappointing harvest or even to your mould not surviving it. A good thing to know, is that your material will never be 100% sterilised as we are not working in a laboratory.

The first step in this method is to grind the straw. You can do this with a shredder or with a small axe. How smaller the straw, how bigger the chance is that the mould will elaborate. Also, by having many small parts of straw, there will be more contact points which makes the mould grow faster. Besides this, the mould likes to grow in the same direction as the fibres of the straw. The second step is to immerse it in water that has a temperature between 60 and 65 degrees. After 15 minutes you can take the straw out and place it on an old sheet to let it cool down. For this, you also need to sterilise the sheet with a 5% dilution of hydrogen peroxide. An easy way to do this, is by using a plant sprayer. As it is a flammable liquid, it is also important to use gloves. When the straw has cooled down, you put it in buckets that can be closed. You can, for example, get mayonnaise-buckets of 10 or 20 litres at the cafeteria. Don’t forget to also sterilise these with hydrogen peroxide.

The perfect food for mould

An advantage of coffee grounds, is that it is the perfect food for mould. When you keep coffee grounds for two days, there is already green mould growing on it. We actually want to avoid this mould as it is our biggest enemy when growing mushrooms! However, it does prove that coffee grounds are the best nutrition. When you have collected your coffee grounds (for example at home, an office or a restaurant), you also have to sterilise it. You can do this in a pressure cooker by letting it rest in layer of water for 15 minutes. Then, you put in a sterilised, closable bucket so it can cool down.

IMG_5822The next step is to take a sterilised bucket where you can mix all the ingredients in. In total, you need 10 litres of straw, circa 500 grams of coffee grounds and the spawn. Then, you put the mixture in a bag that contains a minimum of air. It is also important to close it firmly. On the picture you can see the ‘sausages’. These contain pink and blue oyster mushrooms. Every sausage can be harvested around three times and can give you a total of one kilo of mushrooms.

You can hang or lay the sausage in a dark and moist place. For example in a basement, barn or garage. The most ideal is a humid bathroom. When the location is not moist enough, you can place a damp towel over the sausage. When you found the perfect spot, it is time to let it rest for four days so the spawn can create a network. Then, make cuts in the plastic. After a few weeks you can spot the mushrooms!


Do you also want a permaculture design with mushrooms? You can always contact me!