Mushroom Fruiting Stage

Mushroom Fruiting Stage
Chestnut Mushrooms

The fruiting stage is a critical phase in mushroom cultivation where the mycelium produces the actual mushroom fruit bodies. Understanding the subtleties of this stage can significantly influence the yield and quality of the harvest.

This stage is characterized by the growth of mushroom pins that eventually grow into full-sized fruit bodies. Managing environmental conditions, monitoring growth, and proper harvesting are some of the critical aspects of this phase.

Define pinning:

Transitioning from the Bulk Substrate Stage

The transition from the bulk substrate stage to the fruiting stage is marked by a fully colonized substrate that's ready to support fruit body formation. The surface of the substrate, often referred to as the mycelial cake, should be white and free from contaminants.

Preparing for the fruiting stage usually involves changes in environmental conditions, like reduced temperatures and increased light exposure. At this stage, the mycelial cake is often misted and may be introduced into a specialized fruiting chamber.

Fruiting Chambers

Shotgun Fruiting Chamber (SGFC)

The Shotgun Fruiting Chamber (SGFC) is a simple and effective way to provide the high humidity levels required for fruiting. It is usually made from a clear plastic tote with holes drilled 2 inches apart in all direction on all six sides. The tote is 1/4 filled with perlite, which helps maintain humidity.

Maintenance of a SGFC involves regular misting to maintain humidity and occasional fanning for fresh air exchange. Monitoring the chamber to ensure that conditions remain stable is also essential.


Monotubs are a popular choice for those aiming to grow larger quantities of mushrooms, particularly those species that thrive in compost-based substrates. Some experienced cultivators even modify monotubs with automated systems to precisely control conditions like temperature and humidity, optimizing the environment for mycelial growth and pinning.

The setup process involves layering a substrate and colonized grain spawn in a large plastic tub. This container is usually sealed to create a microclimate that's conducive to mycelium growth. Once the substrate is fully colonized, the conditions within the tub are adjusted to initiate the fruiting stage. To minimize the occurrence of mushrooms growing along the sides of the tub, a phenomenon known as "side pinning," a liner (garbage bag) can be used. However, it's worth noting that even with a liner, side pins can still occur based on personal experience.

Martha Tent

A Martha Tent is essentially a greenhouse-style tent often used for mushroom cultivation to maintain high levels of humidity. It allows for more vertical growing space and can accommodate multiple shelves of substrate.

One of the main advantages of using a Martha Tent is its scalability; it can easily be adjusted to fit the needs of both small and large cultivation projects. However, it may require a more complex setup, including humidifiers and fans to maintain optimal conditions.

Maintenance involves monitoring and adjusting humidity levels, as well as ensuring proper air exchange. Unlike smaller fruiting chambers, a Martha Tent often benefits from automated systems to manage these environmental factors.

Environmental Conditions

Optimal temperature for the fruiting stage usually ranges between 55-75°F, depending on the species. Humidity levels should remain high, often above 90%. These conditions ensure that the mycelium can allocate its energy towards producing fruit bodies.

Light is another crucial factor; although mushrooms are not plants and do not require light for photosynthesis, they do need light to trigger the pinning process. Fresh air exchange (FAE) is vital for encouraging healthy mushroom growth and can be facilitated by fanning or automated systems.

Pin Formation

Pinning is the initial stage of mushroom formation, where small, round formations appear on the substrate surface. Initiation is usually triggered by a change in environmental conditions, such as light exposure and a drop in temperature.

Several factors affect pin formation, including substrate quality, humidity, and air exchange. The presence of pins is often the first sign that the fruiting stage is progressing successfully.

Monitoring and Troubleshooting

Healthy pins will grow into robust fruit bodies, which are the actual mushrooms. Aborted pins, discoloration, or strange odors are indicators of problems that need immediate attention.

Common issues include bacterial contamination, insufficient fresh air exchange, and poor humidity control. Addressing these issues often involves adjusting environmental conditions and may require the removal of contaminated portions.


The ideal time to harvest mushrooms varies by species but is usually right before or just as the caps uncurl. Being timely in harvesting ensures maximum potency and yield.

After harvesting, it's crucial to examine the mycelial cake for any signs of contamination and to prepare it for potential future flushes. A flush is a period during which mushrooms grow, and multiple flushes can be obtained from the same mycelial cake.

Drying and Storage

Drying is the preferred method for long-term storage of mushrooms. Various techniques include air drying, using desiccants, or employing a dedicated food dehydrator.

For short-term storage, fresh mushrooms can be kept in the refrigerator, but for more extended periods, dried mushrooms should be stored in airtight containers to preserve their potency and prevent contamination.

Good Luck My Friends

The fruiting stage represents the climax of your diligent efforts in mushroom cultivation. Successfully navigating this stage requires acute attention to environmental conditions, vigilant monitoring for signs of growth or potential issues, and timely interventions to optimize the growing process.

Your skill in managing these elements can significantly impact the quality and quantity of your mushroom yield, making all the preceding hard work pay off.

As someone who has navigated the complexities of mushroom cultivation, I know the journey can be filled with both excitement and challenges. In my own experience, mistakes were not just inevitable but valuable learning opportunities. The wealth of advice and insights available online has been an invaluable resource for me, and I hope that the information provided on this site proves equally beneficial for you.

Wishing you all the best in your mushroom cultivation endeavors. Good luck, and may your harvests be plentiful!

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