Process of Growing Shiitake Mushrooms
Process of Growing Shiitake Mushrooms in Supplemented Sawdust Substrate
Mushroom cultivation is a delicate and intricate process. Among all the mushroom varieties, Shiitake mushrooms are especially coveted for their meaty texture and smoky flavor. Shiitake mushroom cultivation, specifically on supplemented sawdust substrate, is a preferred method because of the significant yield it promises. Here’s a detailed exploration of the process.
Preparing the Substrate
Shiitake mushrooms grow naturally on decaying hardwood trees in the wild. In controlled environments, a blend of hardwood sawdust and organic supplements creates an ideal substrate for shiitake mushroom growth.
The substrate is typically comprised of about 80% hardwood sawdust and 20% organic supplement like wheat bran, rice bran, or soybean meal to provide additional nutrients. The sawdust should be from non-resinous woods like oak, alder, or maple.
After mixing the substrate, the next step is to sterilize it. The aim is to eliminate any microorganisms that could compete with the Shiitake mycelium for nutrients. Sterilization can be done using an autoclave or a pressure cooker at about 15 psi for 2-3 hours. After sterilization, the substrate needs to cool before inoculation.
The inoculation process introduces the mushroom mycelium into the sterile substrate. Shiitake spawn, available in the form of grain spawn, sawdust spawn, or plug spawn, is used for this purpose. Typically, a rate of 1-2% of spawn to the weight of the substrate is recommended.
This step must be performed in sterile conditions to prevent contamination. A laminar flow hood or a still air box can be used. Using a sterile scoop, the spawn is mixed with the substrate, ensuring it is evenly distributed.
Packing the Substrate and Incubation
Once the substrate is inoculated, it is filled into special bags with filter patches to allow for air exchange while preventing contamination. These bags are usually sealed using an impulse sealer. It’s important to pack the substrate firmly but not too tightly; the mycelium needs room to grow.
The bags are then kept in a dark, cool, and humid space for incubation. A temperature between 21-24°C (70-75°F) is optimal for Shiitake mycelium growth. Over the next few weeks, the mycelium will colonize the substrate, turning it a web-like white. This process, known as the spawn run, takes approximately 6-8 weeks.
After the substrate is fully colonized, it’s time for the Shiitake mushrooms to fruit. The fruiting process is triggered by changing the environmental conditions to mimic the natural conditions where Shiitake mushrooms would fruit in the wild.
This includes reducing the temperature to about 10-18°C (50-64°F), raising the relative humidity to about 90-100%, and introducing fresh air and light. Small cuts or holes are made in the bags to allow mushrooms to grow out.
During the fruiting stage, it’s essential to maintain high humidity and provide fresh air to prevent carbon dioxide build-up, which can inhibit mushroom growth. This can be achieved by regularly misting the area and providing proper ventilation.
Harvesting typically occurs within 7-14 days after the initiation of the fruiting stage. The mushrooms are ready to harvest when the edges of the caps are slightly curved down.
Harvesting should be done by hand to prevent damaging the mushrooms. Twist the stem gently at the base, and it should come off cleanly. If any part of the mushroom is left behind, it can rot and contaminate the rest of the substrate.
Rest and Repeat
After the first flush of mushrooms, the substrate needs a rest period of about 2 weeks before initiating a new fruiting cycle. During this rest period, it’s essential to maintain proper humidity to prevent the substrate from drying out.
The substrate can typically produce about 4-6 flushes of mushrooms before it is exhausted. After this, it can be composted or used as a soil supplement in your garden.
Growing Shiitake mushrooms on supplemented sawdust substrate is an exciting and rewarding process. By creating the right environment and carefully managing each stage of the growth cycle, you can cultivate your own high-quality Shiitake mushrooms. It requires patience and meticulousness but the end product is well worth the effort. The ability to control the growing conditions also gives you the advantage of producing consistent, high-quality yields throughout the year.
Full Credit to Bob, the owner of Whole Earth Harvest, takes us through the stages of when a shiitake mushroom block begins to ‘pin’, through the time it takes for the mushrooms to fully grow, and when they are ready to be picked.
This is a solid first-hand video from a commercial scale grower who is sharing his own thoughts on growing Shiitake mushrooms. On this page, we are also showing an interesting video talking about other influences on Shiitake growth.