Don't Go to the Forest, Grow Mushrooms at Home

In short: Wood-decay mushrooms such as oyster, shiitake or nameko grow at home on sterilised straw or on freshly cut deciduous logs. Straw colonises in 3 – 4 weeks at 20 – 25 °C; logs need 2 – 4 months and then fruit for about 3 seasons on softwood and 5 – 6 years on hardwood.

While there are many mushroom foragers who collect mushrooms for pleasure and find their greatest joy in discovering a bolete nestled on a mossy forest bed, there are also many who appreciate mushrooms from their own production. Instead of going to the forest, they simply head to their cellar or garden. The most commonly home-cultivated varieties are button mushrooms or some of the so-called wood-decay fungi. This group includes, for example, the black poplar mushroom (Latin: Agrocybe aegerita), the oak mushroom better known as Shiitake (Latin: Lentinus edodes). Popular is also wood ear or Judas's ear (Latin: Auricularia auricula). Wood-decay fungi also include nameko mushroom (Latin: Pholiota nameko) and sheathed woodtuft (Latin: Kuehneromyces mutabilis). The most well-known and most frequently cultivated wood-decay fungus is the oyster mushroom (Latin: Pleurotus).

• Black poplar mushroom (Latin: Agrocybe aegerita) originates from the Mediterranean. Its fruiting bodies grow to a diameter of approximately 5 – 15 cm, and grow in clusters. The fruiting body (cap) is brown in color, while the stem is white. Black poplar mushroom can be grown on wooden logs or branches. Sawdust from deciduous trees or straw bales work well too. The mycelium of black poplar mushroom can fruit for up to 5 years.

• Shiitake (Latin: Lentinus edodes) is most commonly grown on a wooden substrate. It fruits in three waves, with the fourth typically being very weak. Shiitake mushroom originates from Southeast Asia, gaining popularity through its abundant use in Japanese and Chinese cuisine. The Shiitake fruiting body has a light brown color, with the cap growing to a size of 1 – 10 cm in diameter.

• Judas's ear – wood ear (Latin: Auricularia auricula) is a visually very interesting mushroom. It has a shell-like, cup-shaped, or oyster-like form. The fruiting body feels rubbery or gelatinous to the touch, and is sticky when wet. The color of the fruiting body is reddish-brown, with the underside being lighter. As the name itself suggests, this mushroom thrives best on elderberry wood (which can be living or dead).

• Nameko mushroom (lat. Pholiota nameko) originates from Southeast Asia and is widely cultivated in China, Vietnam, and Japan. The fruiting bodies of this mushroom have a brown color, and the surface of young caps is often covered with a layer of slime. Although this may seem strange, this slime is precisely what gives dishes enriched with nameko mushrooms their characteristic taste and yellow coloring. Nameko mushrooms are most commonly grown on wood substrate.

• Oyster mushroom (lat. Pleurotus) exists in several species. The most well-known are the oyster mushroom (lat. Pleurotus ostreatus), veiled oyster mushroom (lat. Pleurotus dryinus), pink oyster mushroom (lat. Pleurotus djamour), and king oyster mushroom (lat. Pleurotus eryngii). The fruiting bodies of oyster mushrooms have a cup-like shape, which especially in the case of the oyster mushroom resembles an oyster shell. Oyster mushrooms grow in clusters. They can be grown on both wood and straw substrate.

Growing Wood-Decay Mushrooms on Straw

Growing wood-decay mushrooms on straw is not complicated at all. The basis is quality rye, barley or wheat straw, ideally chopped short, that has been stored in a dry environment. The straw must not be mouldy, rotten or freshly harvested, to prevent contamination by mould and subsequent failure of the growing attempt. Even quality straw should be sterilised before inoculation. This is done using hot water in which the straw is submerged. In practice, sterilisation most commonly looks like this: the straw is packed into a large, sturdy bag and poured over with boiling water. There should be enough water to cover even the top layer of straw. The straw is left in the water bath for approximately one hour and then the bottom corners of the bag are cut off to allow the water to drain. For perfect sterilisation of the straw, pouring hot water over it is repeated once more. After sterilisation, the bundle of straw is allowed to cool to a temperature of approximately 30 °C. At this point, the straw is ready for inoculation with one of the wood-decay mushrooms. Inoculation substrate or special plugs are inserted into the bag with straw so that there are alternating layers of straw and a thin layer of special substrate in the bag. The plugs are placed around the perimeter of the bag and inside the straw. The bag is then tied up and placed in a location with a temperature range of 20 – 25 °C. At this temperature, the substrate will colonise in approximately 3 – 4 weeks (always depending on the specific mushroom species). Once the contents of the bag are well colonised (completely white), several holes are cut around the perimeter of the bag. The bag with straw is then moved to a cooler, bright location. Fruiting bodies will soon start growing from the prepared holes, the specific time always depends on the temperature and the mushroom species being grown. The growth rate of mushrooms can therefore be slightly adjusted – in cooler locations, fruiting bodies grow more slowly. Mushrooms can be grown on straw until the straw softens and begins to decompose, after which a new mushroom culture must be established.

Growing Mushrooms on Wood

Wood from deciduous trees is suitable for growing wood-decay mushrooms, logs from conifers are unsuitable. Most commonly used are freshly cut (max. 1 – 2 months ago) logs from poplar, alder, willow; oak and beech logs last very long. Among deciduous trees, only apple and walnut wood have proven unsuitable. Suitable logs should have a diameter of at least 15 cm and a length in the range of 30 – 40 cm.

Growing wood-decay mushrooms on wood takes place in four phases:

• preparing suitable wood (log)
• inoculation with spawn
• mycelium colonization of logs
• fruiting body formation.

The first phase, which largely determines the success of wood-decomposing mushroom cultivation, is the selection and preparation of suitable wood. Choose a log that meets the criteria mentioned above. Do not remove the bark from the logs. Wood-decomposing mushrooms can be grown on cut surfaces or in individual holes (notches). Notches are best cut into logs with a chainsaw. The notches are cut to 1/3 of the length, alternating on both sides. Holes are drilled around the circumference of the log, with a suitable diameter of 12-15 mm. This is followed by the second, equally important phase - inoculation. Inoculation into notches is carried out by placing a clean (preferably heat-sterilized) board at the bottom of the bag. Mushroom spawn is poured onto it, and the prepared log is placed on it with the cut surface facing down. Spawn is also poured onto the upper cut surface and everything is again covered with a board. It is advisable to nail the boards to the log so they adhere better. The spawn is pressed as much as possible into the holes and then sealed with grafting wax or paraffin. After inoculation, the bag with the log is tied to prevent the spawn from drying out. In the third phase of cultivation, the inoculated logs are placed in a location with a temperature of around 20°C. In summer, the logs can be placed in a shady spot outdoors. Multiple logs are prepared in the same way and can be left to colonize together, for example, in a dug pit or wrapped in foil. The wood colonizes for approximately 2-4 months, hardwoods even longer. The final step to success is removing the logs from the bags and triggering fruiting body formation. Fruiting body formation is initiated by burying the log in the ground with 2/3 below the soil surface and 1/3 above. The logs are buried in a shady location where the groundwater level is not high. In water, the mycelium quickly dies and the entire crop is lost. If the entire process is successful, fruiting bodies will begin to form soon. Prepared logs usually fruit in spring and autumn. On softwood, fruiting bodies grow for approximately 3 seasons, while on hardwood, fruiting bodies can grow for 5-6 years.

Wood-decomposing mushrooms can also be grown from prepared special substrates. The advantage of these substrates is the simplicity of preparation, while the disadvantage is the relatively short fruiting period of the mushrooms.