Many mushroom species are suitable for cultivation on fresh wood. The easiest to cultivate are shiitake and oyster mushroom, as they are less demanding species. Still, it is possible to cultivate most mushrooms that naturally grow on wood – tree stumps, trunks of dying or dead trees, branches, etc. Among the edible species possible to cultivate on wood are, besides oyster mushroom (Pleurotus ostreatus) and shiitake mushroom (Lentinula edodes), also the winter mushroom (enokitake, Flammulina velutipes), poplar mushroom (Agrocybe aegerita), reishi mushroom (Ganoderma lucidum), white elm mushroom (Hypsizygus ulmarius), Hypholoma capnoides mushroom and others.
The easiest method of cultivating mushrooms is cultivation on fresh wood. This method does not require substrate sterilisation, which is necessary when using other cultivation methods. Logs and stumps of freshly cut trees are suitable for the cultivation, provided that they are not decayed or rotten. In addition, tree stumps must not leak tree sap that often causes the mycelium to rot; in case of leaking, it is best to wait a few weeks for them to dry. The bark should be intact, since it prevents moisture evaporation, thus providing ideal conditions for the mycelium to grow, and at the same time prevents the unwanted fungi and other organisms to access the wood.
For mushroom cultivation, hardwood from deciduous trees, such as oak for shiitake, beech, hornbeam, maple and alder tree, is most suitable, as it provides the highest yields (for example oak gives two times higher yield than beech). On the other hand, softer wood species decompose faster and give smaller yields. Wood from coniferous trees has a specific composition, which makes it suitable only for the cultivation of certain mushroom species.
For mushroom cultivation on tree stumps, their entire surface is drilled in a zigzag pattern and plug spawn inserted in the holes. Alternatively, a stump can be cut transversely, the top surface spread with grain spawn and covered with a remaining cut-off wooden disc. The so prepared stump has to be covered with a plastic film and soil or leaves to protect it from drying up, direct sunlight and animals that feed on spawn. Mycelium usually needs a couple of months to colonise the substrate.
Once white rings appear on the surface of the stump, indicating it is colonised with mycelium, the polyvinyl film and soil or leaves can be removed, although it is often better to leave it partially covered. When the weather conditions are favourable (most often during the autumn), mushrooms start to grow out of the tree stump and continue growing until the wood is completely decayed, which can last a couple of years. During this period, it is necessary to maintain a humid environment out of direct sunlight and strong wind.
Using this method, the unwanted stumps in gardens can be turned into a ‘mushroom garden’ for a couple of years. Thus, a couple of kilograms of mushrooms can be grown and eventually stumps are transformed into humus.