The Pinning Process

The pinning process is the process whereby the mycelium starts to channel nutrients for the creation of the mushroom upon exposure to favorable fruiting conditions. This takes place once the mycelium has expanded to the maximum extend and faces nutrient constraints due to competition with other organisms or natural physical barriers. In my case, once the mycelium has eaten through the approximately ten pounds of hardwood based substrate, the mycelium knows that it cannot expand any longer and seeks favorable conditions to begin the fruiting process. Let us then examine the critical factors for successful pinning, as listed below:

1) Species

2) Timing

3) Cuts for pins

4) Fruiting room conditions (oxygen, humidity, lighting)

The first point of consideration is the species that is being grown. Depending on whether the mushroom is cold weather mushroom or a tropical species for example, the mushroom will have a much easier or more difficult time developing initial pins. In my own recent experience, Italian oyster mushrooms and pink oyster mushrooms started pinning, fruited, and went back into dormancy in preparation for the next flush all while the blues failed to pin. This is because blue oyster mushrooms are cold weather species whereas the others are more moderate/tropical climate species. A matter of utmost importance is growing mushrooms which suit the micro climate you are able to generate. If this is not done, yields and grow reliability will not be optimal

The second point is the timing of when the colonized blocks are moved from the colonization room to the fruiting room. If not enough time passes, the blocks will continue to colonize even after being moved to the fruiting room. If too much time passes, the mycelium will start to pin in the bag (usually at the top where there is slightly more oxygen exchange), and prevent effective side fruiting. This allows for the option of top fruiting or still side fruiting with sub optimal yields, but neither is desirable in growing the highest quality gourmet mushrooms. Therefore, blocks should be watched daily and moved into the grow room at the exactly correct time.

On the third point, the cuts you make on the side of the production block determine the growth pattern of the mushrooms. Top fruiting usually produces a much higher number of pins simultaneously but with smaller mushrooms. Side fruiting forces, the mushroom growth through a smaller hole, which produces larger clusters. As my goal is to produce the highest quality mushrooms possible, I am likely to favor side fruiting with smaller pinning holes so as to generate a fewer but larger caps, which are more aesthetically pleasing.

Finally, the exposure to the fruiting conditions is obviously what allows the pinning to start happening. The cuts in the production bag allow for the mycelium to be exposed to higher oxygen levels which is one of the important triggers for pinning. Keep in mind that usually lower lighting and higher humidity - as opposed to the mushroom growth phase - is favored in the pinning process. So while the lighting is normally kept around 500 - 1000 lux during the growth phase, 100 - 200 is recommended for pinning. And while the humidity is usually kept around 85 - 90% for the growth phase, 90 - 95% is recommended for the pinning phase. These would then be adjusted once the pinning occurs en masse across the batch.

In conclusion, none of the above factors is necessarily the most important but all should be considered in the pinning process. By perfecting all of those factors, an incrementally higher mushroom quality is likely to be achieved.