For shiitake mushrooms you usually use logs of 8 - 15 cm diameter and up to 1.20 m long, but short thick logs (50 cm long) can also be used. 50 plugs are suitable for 4-5 logs. Only use wood from deciduous trees, wood from coniferous trees is not suitable. Oak or beech are particularly favourable for shiitake but alder or birch can also be used. See Overview of wood types for a list of wood types for different mushrooms.

It is important to ensure that the logs are moist and do not show signs of other mushroom or fungi at the time of innoculation. Accordingly, they should not have been stored for longer than 3 months after cutting. However, the logs should be stored for at least 6 weeks after cutting to exclude a possible immune reaction of the fresh wood. The bark should be left on and protects the wood. The bark is more durable for logs cut in winter, so this is the best time to cut the logs.

If the logs are quite long, you can optionally cut them into shorter logs after the mycelia has grown (see below). The exception is logs for shiitake mushrooms which are preferably slightly longer.

All mushroom plug types can be stored for up to several weeks in the refrigerator. During this time the mycelia may start to grow out of the plugs, which can also turn brown in places in the case of shiitake.

How to innoculate?

Drill 10 - 15 holes about 5 cm deep spread out over the whole surface of the log. Then hammer the logs into the hole. The plug should not be lose in the hole, it's best if they are quite tight. Since the mushroom mycelia is also contained within the plugs it doesn't matter if mycelia on the outside of the plugs falls off when the plugs are inserted. Around 10 to 15 plugs are necessary per log. But it doesn't matter if you use more. This may even be an advantage, especially with thicker logs. Logs can be inoculated at any time of the year. However, they must be protected from heavy frost, particularly during the first 6 weeks (see below).

After inserting the plugs, it helps to seal the holes with wax or latex to protect against other fungi, insects and drying out. You can also use latex to seal the two ends of the logs (preferably directly after cutting the logs).

Storage after innoculation (growing phase)

It helps to put the logs in a "heap" after inoculation: place a couple of old logs or strips of wood on the bare ground or grass (not on stones or concrete) in a shadowy place in the garden and then pile the logs on top. The logs should then be covered with straw or leaves to a thickness of ca. 20 cm and the whole pile covered with plastic sheeting (see figure at the top of this page). It is important to puncture the plastic foil with plenty of holes for the exchange of air. The logs should stay in the heap for about 12 months. Take care to protect the logs from frost, especially during the first 6 weeks. The storage temperature should not exceed 30°C since excess temperature can damage the mycelia (do not store the logs in the greenhouse during the summer).

Alternatively you can store the logs indoors, e.g. in a cellar. It is important to maintain a high humidity. Put the logs in plastic sacks which have a few holes for the exchange of air. You can then put out the logs into the garden in spring (see below).

After 9 to 12 months the Mycel should be visible on the cut ends of the log (see Figure 1), The growing phase is then finished. However, the appearance of mycel depends on the presence of enough moisture and the mycel may disappear again if the logs get too dry.

If you haven't put the logs in the garden in a heap for several months, but have stored them in the cellar after inoculating in Autumn, you can  put them out in garden in the Spring. The storage place for the shiitake log should be shadowy. Place the logs on the bare soil and keep them moist using a watering can if necessary. During the growing phase, an ideal place is below bushes or in high grass under trees . Moisture evaporation from the vegetation creates the ideal microclimate. In such conditions,  coverage with a plastic sheet is not absolutely necessary. In longer dry periods, you should water the logs from time to time with a watering can (in very dry months 1-2 times per week). However, avoid permanent puddles of water.

After the growing phase, the logs are frost resistant but you should avoid extremely heavy frost by covering them up (e.g. with straw or leaves).

The following applies to all other mushroom types apart from shiitake:
Other mushroom types require direct contact with the soil. If the logs and very long and thick you can cut them after the growing phase into several small logs with a length of ca. 25 - 30 cm. Then bury the logs in a shadowy, sheltered part of the garden to up to a third of their length. In the case of Stockschwämmchen, you must lay the logs flat and bury the bottom half of the log in the ground. With other mushroom types, the logs are buried vertically. The shiitake does not need direct soil contact and can be lent agains a fence. Protect the logs against snails - snails like mushrooms very much.

Shiitake logs which have already finished the growing phase can then be put indoors in the cellar in late Autumn. The warmth accelerates the growth of the mushrooms. Since the logs must never be allowed to dry out completely, immerse the logs occasionally for several hours in a bucket of cold water ca. 1 x per week. If the log is too long to be immersed fully in the bucket, turn it round after an hour or two and immerse the other end.

Notes on the maturing phase

In order to accelerate the mushroom growth after the growing phase (after at least 12 months) you can immerse the shiitake logs for about 24 hours in cold water (turn the logs around to immerse the other end if they are too long). Mushroom growth is accelerated by the shock of the cold water. Following this, bang each of the logs three to four times quite hard with the cut ends on a stone or concrete surface (without breaking the log). This also accelerates mushroom growth.

Shiitake logs can be lent against a fence or tree or wall so as not to obstruct the mushrooms when they emerge. If the log is fully mature, the first signs of mushrooms should appear 14 days after immersing in water, and the mushrooms can be harvested quite soon afterwards. Protect the logs against snails. For example, you can put them between branches or in a greenhouse (but no hotter than 30 °C). Logs for other mushroom types are partially buried in the ground (see above) and need not be immersed in water.

In dry weather, keep the logs moist with rain water or a watering can.

After harvesting, the shiitake logs need to recuperate for 6-8 weeks during which time they might start to appear again. In order to cause the mushroom the grow after this period, you can immerse them in water again as described above. This treatment can be repeated every few weeks.

In Summer, make sure that the storage location is shadowy and keep each log moist with rain water or with a watering can. Occasional immersion in water in a bucket is also favourable (see above).

Notes on harvesting

The first mushrooms will probably grow close to the holes where the plugs were inserted. You may find that initially only 1-2 mushrooms appear. However, the mushroom mycelia grows throughout the log over a petriod of several years. Be patient - the logs can produce mushrooms for 4-5 years (according to thickness). The logs are only fully used up when the wood is rotten and starts to fall apart.

The mushroom should be harvested when the skin below the cap has opened up and the gills of the mushroom are visible but the edge of the cap is still slightly rolled inwards. Break or cut the mushroom away from the log, leaving as little of the mushroom stem attached to the log.

Nicola Krämer, Hannover * Marketing of mushroom-growing products * Home